# Vacuum Stabilization



## BangleGuy

So there are a least of few of us that are venturing into the vacuum stabilization process for the first time and I thought I would start a new thread for all things related to this subject.

(First let me say that I am in no way connected with any products that I talk about here, so this is just product and process review versus a sales pitch.)

Recently I bought a vacuum chamber and stabilizing solution from Curtis Seebeck at TurnTex (turntex.com). I also bought a vacuum pump from Harbor Freight and a toaster oven with a timer from Lowes. I began stabilizing blanks and having too much fun:wacko1:. Right out of the gate, I will say that my vacuum pump gets me only +/- 24" of Hg, which is a little disappointing. 

(I will get some pictures of my setup onto this thread soon.)

So far; what I have noticed is that the turntex stuff works great and Curtis makes a nice product. I have stabilized about 20 bangle blanks and have had good success achieving a hardened product which resists moisture and finishes well. 

I have also noticed that I am getting some leaching of tanins (or other dark material) into my Cactus Juice. The Juice starts out with a corn syrup color, and mine (after 20 assorted woods) is the color of a nice honey brown ale. I double stabilized some FBE and I believe my honey brown juice has muddied the FBE. So first lesson learned, keep your dark woods separate from the light woods! :dash2: 

That's enough for now... more to come.

BG


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## LoneStar

Thanks for that. I'm looking at the same sytem one of these days, I was curious what others experiences are.


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## kweinert

BangleGuy said:


> I also bought a vacuum pump from Harbor Freight and a toaster oven with a timer from Lowes. I began stabilizing blanks and having too much fun:wacko1:. Right out of the gate, I will say that my vacuum pump gets me only +/- 24" of Hg, which is a little disappointing.



Which one of their pumps did you buy?


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## Vern Tator

Great idea, thanks for starting this thread. This may make some of my blanks that are really beautiful , but soft, usable.


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## bearmanric

I have the new big chamber i'm around 28Hg. Going to be turning some Box elder burl calls today. Love the system. Rick

This is the $199.00 Vaccum from Harbor freight. The way i stabilize in this chamber is in a dish. The darker Fluid is Teak oil with half a capful of japan drier. Calls when clicked together sound like glass. Finishish is all the way through. Rick

http://img.Rule #2/albums/v68/bearmanric/calls2001-22.jpg
http://img.Rule #2/albums/v68/bearmanric/calls2002-16.jpg


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## kweinert

bearmanric said:


> I have the new big chamber i'm around 28Hg. Going to be turning some Box elder burl calls today. Love the system. Rick
> 
> This is the $199.00 Vaccum from Harbor freight. The way i stabilize in this chamber is in a dish. The darker Fluid is Teak oil with half a capful of japan drier. Calls when clicked together sound like glass. Finishish is all the way through. Rick



That's the pump I have on order. They're backordered at the moment. I also went with the larger chamber (which is, essentially, backordered as well :)

Do you turn and then finish? I know that's how it's normally done, but your use of the word 'stabilize' got me slightly confused since stabilizing is normally done first - right?


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## Kevin

BangleGuy said:


> ... I also bought a vacuum pump from Harbor Freight ... I will say that my vacuum pump gets me only +/- 24" of Hg, which is a little disappointing. ...



I got my first order from Curtis yesterday. I dug my old vacuum pump out a while back knowing I was going to order his system and plugged it in and the drive link broke almost immediately. So I need to tear this thing down. It's grimy and dirty but unless the pump itself is seized up it's still in good shape. I need to replace the gauge and drive link but ot should be okay. 

If you want to get close to 30 inches of mercury you'll need a pump like this guys - a two stage pump with at least 5CFM. 

[attachment=3229]

Rick's pump pulling to 28" Hg is fine for stabilization I am guessing. I'll cur a small block in half and pull one piece to 28 and the other to 29 and see if there's a discernible difference but I bet there won't be. 


Hope to get to the pump in a day or three.


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## BangleGuy

I bought the $100 vacuum pump from Harbor Freight, so stay clear of that one (although it was the only one in stock when I went to the store). I have been roughing out my blanks first and then stabilizing. The blanks can get a little wonky depending on how the juice is absorbed into the wood grain. So just plan on taking a good amount for cleanup passes. 

I did stabilize some wood blocks and Holy Cow! :dash2: did they suck up the juice! In the end a lot of the juice ran back out of the wood and cured in the bottom of my toaster oven :diablo:. This test was on some spalted maple, so it was a very light weight wood. I will stick with stabilizing rough blanks for the future.


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## kweinert

Kevin said:


> BangleGuy said:
> 
> 
> 
> ... I also bought a vacuum pump from Harbor Freight ... I will say that my vacuum pump gets me only +/- 24" of Hg, which is a little disappointing. ...
> 
> 
> 
> 
> If you want to get close to 30 inches of mercury you'll need a pump like this guys - a two stage pump with at least 5CFM.
Click to expand...


The one I have on order is a 2 stage, 3CFM pump. I figure I can use it for this and for a veneer press when I get back to doing that sort of work as well.


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## bearmanric

I turn my calls first Cocobolo or bocote, Stabilize for a hour. then let sit over night, Next day i put the call on the mandrel wet sand with 600 grit then buff in the walnut oil wax's real good get alot of complementson my finish. The old time duck call makers would soak there calls in boiled linseed oil and some japan drier for 6 months or longer. I learned to speed it up a bit. I was taught to turn my blanks round better penatration a save juice. Let your blanks sit over night there is air pockets in the blank way better blanks are on the bottum. Rick

Make a difference wereyour at on elevation i'm 100 feet above sea level.


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## kweinert

bearmanric said:


> I turn my calls first Cocobolo or bocote, Stabilize for a hour. then let sit over night, Next day i put the call on the mandrel wet sand with 600 grit then buff in the walnut oil wax's real good get alot of complementson my finish. The old time duck call makers would soak there calls in boiled linseed oil and some japan drier for 6 months or longer. I learned to speed it up a bit. I was taught to turn my blanks round better penatration a save juice. Let your blanks sit over night there is air pockets in the blank way better blanks are on the bottum. Rick
> 
> Make a difference were your at on elevation i'm 100 feet above sea level.



I'm about a mile higher than that here in Denver.

Thanks for sharing your info, it's much appreciated.


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## BangleGuy

bearmanric said:


> I turn my calls first Cocobolo or bocote, Stabilize for a hour. then let sit over night, Next day i put the call on the mandrel wet sand with 600 grit then buff in the walnut oil wax's real good get alot of complementson my finish. The old time duck call makers would soak there calls in boiled linseed oil and some japan drier for 6 months or longer. I learned to speed it up a bit. I was taught to turn my blanks round better penatration a save juice. Let your blanks sit over night there is air pockets in the blank way better blanks are on the bottum. Rick
> 
> Make a difference wereyour at on elevation i'm 100 feet above sea level.



Rick, So you don't use the Cactus Juice? You mentioned teak oil and japan drier... what is the recipe for this process? Thanks for sharing!! 

Eric


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## bearmanric

yes i use cactus juice but on my oily woods i use teak oil the japan drier helps harden inside the wood. . i have done walnut oil to it works. I let the calls sit a few days in warm area. i buy a gallon of seafin teak oil at my ace hardware they have japan drier to. They say to put only a cap ful of japan drier to a quart of teak oil. Rick


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## kweinert

kweinert said:


> That's the pump I have on order. They're backordered at the moment. I also went with the larger chamber (which is, essentially, backordered as well :)



Probably the shortest back order I've ever seen - just got a notice that it shipped today.


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## bearmanric

Good vaccum and chamber. It will save you money in the long run. Rick


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## Kevin

bearmanric said:


> Good vaccum and chamber. It will save you money in the long run. Rick



Not the juice though. $100 a gallon wish I could figure out what it is. Some kind of polymer I'm sure. I'm going to experiment I bet I find something works as well but much cheaper.


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## DKMD

I'm not sure about cactus juice, but most of the commercial stabilizers use methyl methacrylate(MM) if I'm not mistaken. There are a ton of applications for that stuff. The glue for joint replacements is MM. It's used in microbiology labs as a fixative for slides and tissues. I couldn't tell you where to source it, but I'd sure be looking at $100/gallon.


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## Kevin

DKMD said:


> I'm not sure about cactus juice, but most of the commercial stabilizers use methyl methacrylate(MM) if I'm not mistaken. There are a ton of applications for that stuff. The glue for joint replacements is MM. It's used in microbiology labs as a fixative for slides and tissues. I couldn't tell you where to source it, but I'd sure be looking at $100/gallon.



The juice is not nearly as toxic. Loctite corporation makes the stuff that most of the stabilizers have used for years which is Resinol 90C and supposed to be so dangerous to work with that it can kill you if you aren't extremely cautious. I don't know how accurate that is but I wasn't going to fool with something that's supposed to be that nasty. 

The cactus juice is, I believe a polymer or copolymer with a percentage of CA in it. This is my guess as a part time amateur chemist that still has all his fingers, toes, and eyes. Even eyelashes and eye lids, though they have been singed a few times.


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## BangleGuy

Here is my vacuum setup. Pretty straight forward. I bought the juice saver and weight so I don't have to use the full volume. The vacuum pump is mediocre. Notice my juice is pretty brown and it is only half gone. No light woods for this juice :dash2:

[attachment=3265]


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## Vern Tator

Nice, clean, well thought out set up


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## TurnTex

BangleGuy said:


> Right out of the gate, I will say that my vacuum pump gets me only +/- 24" of Hg, which is a little disappointing.



I would not be so quick to be disappointed, Eric! Remember, vacuum is completely different than pressure and is physically limited. The definition of absolute vacuum in simplistic terms is the absence of all air. You are at a much higher elevation, thus the air is thinner where you are, in other words, there is less air to remove at your elevation than there is at sea level!

The maximum absolute vacuum *at sea level* is 29.92" Hg on a standard atmospheric day. Of course, it is impossible to achieve an absolute vacuum, even in the most perfect laboratory setting but we can get pretty close. Then, for every 1,000 feet above sea level, you loose 1" Hg of vacuum! So, for your location (I looked your city up in my order database and then on google to fine the elevation) you are approximately 4,600' above sea level. Take 29.92 and subtract 4.5 and you end up with 25.42" Hg as the maximum theoretical vacuum for your location. Now, take the 24" that you are getting and divide it by 25.42 and you end up with .944 or a 94.4% vacuum! Considering that your pump is only rated to 29" at sea level or a 96.9% vacuum, you are getting a really good vacuum for your elevation and your pump!


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## BangleGuy

TurnTex said:


> BangleGuy said:
> 
> 
> 
> Right out of the gate, I will say that my vacuum pump gets me only +/- 24" of Hg, which is a little disappointing.
> 
> 
> 
> 
> I would not be so quick to be disappointed, Eric! Remember, vacuum is completely different than pressure and is physically limited. The definition of absolute vacuum in simplistic terms is the absence of all air. You are at a much higher elevation, thus the air is thinner where you are, in other words, there is less air to remove at your elevation than there is at sea level!
> 
> The maximum absolute vacuum *at sea level* is 29.92" Hg on a standard atmospheric day. Of course, it is impossible to achieve an absolute vacuum, even in the most perfect laboratory setting but we can get pretty close. Then, for every 1,000 feet above sea level, you loose 1" Hg of vacuum! So, for your location (I looked your city up in my order database and then on google to fine the elevation) you are approximately 4,600' above sea level. Take 29.92 and subtract 4.5 and you end up with 25.42" Hg as the maximum theoretical vacuum for your location. Now, take the 24" that you are getting and divide it by 25.42 and you end up with .944 or a 94.4% vacuum! Considering that your pump is only rated to 29" at sea level or a 96.9% vacuum, you are getting a really good vacuum for your elevation and your pump!
Click to expand...



Curtis my friend! Welcome to the WB!!! Glad you could make it 

Hey, now THAT is some good advice! I guess I was assuming that the vacuum gage was reading in sort of a PSIg versus PSIa (gage vs absolute). Considering an absolute pressure gage will read atmospheric pressure + container pressure. .. then what we are talking about is that the vacuum gage is reading in absolute (since it takes into consideration atmospheric)?


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## TurnTex

Kevin said:


> If you want to get close to 30 inches of mercury you'll need a pump like this guys - a two stage pump with at least 5CFM.



I have to respectfully disagree with you, Kevin. The CFM rating on a vacuum pump does nothing to generate a deeper vacuum, it just gets it there quicker. The large chamber that I make only contain .259 cubic feet of air so the difference between a 1 cfm and 5 cfm pump is going to be negligible. Also, there is going to be a limitation on the CFM that you are able to move through a typical vacuum hose to begin with. To get the best pump for the deepest vacuum, you need to look at the rated vacuum the pump generates. Most HVAC type pumps are rated in microns rather than " Hg. The lower the micron number, the higher the vacuum it will generate. a good pump should be able to pull a 25-50 micron vacuum which is a really deep vacuum.


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## kweinert

TurnTex said:


> Kevin said:
> 
> 
> 
> If you want to get close to 30 inches of mercury you'll need a pump like this guys - a two stage pump with at least 5CFM.
> 
> 
> 
> 
> I have to respectfully disagree with you, Kevin. The CFM rating on a vacuum pump does nothing to generate a deeper vacuum, it just gets it there quicker. The large chamber that I make only contain .259 cubic feet of air so the difference between a 1 cfm and 5 cfm pump is going to be negligible. Also, there is going to be a limitation on the CFM that you are able to move through a typical vacuum hose to begin with. To get the best pump for the deepest vacuum, you need to look at the rated vacuum the pump generates. Most HVAC type pumps are rated in microns rather than " Hg. The lower the micron number, the higher the vacuum it will generate. a good pump should be able to pull a 25-50 micron vacuum which is a really deep vacuum.
Click to expand...


Mine should be OK then, presuming it works as advertised. It's rated at 25 microns. So, given the earlier discussion, here in Denver I shouldn't expect to see more than 24.7 on the gauge when it's working well. And that's an optimal number. I think that bangleguy and I have the same pump so I should really be expecting around 23.6 or so.

Reactions: Creative 1


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## TurnTex

BangleGuy said:


> I did stabilize some wood blocks and Holy Cow! :dash2: did they suck up the juice! In the end a lot of the juice ran back out of the wood and cured in the bottom of my toaster oven :diablo:.



Did you wrap the blanks with foil and what temperature did you cure them at? Did you verify the temperature with a separate oven thermometer placed inside the oven or did you just go by the dial?

Cactus Juice polymerizes between 178° and 204° F and takes 6-10 minutes at that temperature. If you are running at a higher temperature, you will quickly pass through the "window" before the 6-10 minute time. As with any resin, the higher the temperature, the lower the viscosity. As the viscosity goes down, more of the resin will run out of the blank.

DO NOT trust the gauge on your toaster oven! They are terribly inaccurate at lower temperatures! On the 3 that I have tested, when set at 200° F, they all were actually at 275° F or higher! One of my toaster ovens, when set at 200° F is actually running at 325° F on the thermometer in the oven!! Get your temperature down to as close to 200° F as you can get and you will have a lot less "Juice" come out of the blank. Some is going to come out regardless but it will be minimized at the correct temperature.


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## TurnTex

DKMD said:


> I'm not sure about cactus juice, but most of the commercial stabilizers use methyl methacrylate(MM) if I'm not mistaken. There are a ton of applications for that stuff. The glue for joint replacements is MM. It's used in microbiology labs as a fixative for slides and tissues. I couldn't tell you where to source it, but I'd sure be looking at $100/gallon.



Cactus Juice is NOT MMA (methyl methacrylate) It is a proprietary blend of methacrylate ester. Methyl methacrylate is HIGHLY flammable and has potential health risks. It can certainly be used to stabilize and could possibly be obtained cheaper. Many of the professional stabilizers are using a methacrylate ester blend and a lot are using Resinol 90c which is chemically very similar to Cactus Juice.

Reactions: Creative 1


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## BangleGuy

TurnTex said:


> BangleGuy said:
> 
> 
> 
> I did stabilize some wood blocks and Holy Cow! :dash2: did they suck up the juice! In the end a lot of the juice ran back out of the wood and cured in the bottom of my toaster oven :diablo:.
> 
> 
> 
> 
> Did you wrap the blanks with foil and what temperature did you cure them at? Did you verify the temperature with a separate oven thermometer placed inside the oven or did you just go by the dial?
> 
> Cactus Juice polymerizes between 178° and 204° F and takes 6-10 minutes at that temperature. If you are running at a higher temperature, you will quickly pass through the "window" before the 6-10 minute time. As with any resin, the higher the temperature, the lower the viscosity. As the viscosity goes down, more of the resin will run out of the blank.
> 
> DO NOT trust the gauge on your toaster oven! They are terribly inaccurate at lower temperatures! On the 3 that I have tested, when set at 200° F, they all were actually at 275° F or higher! One of my toaster ovens, when set at 200° F is actually running at 325° F on the thermometer in the oven!! Get your temperature down to as close to 200° F as you can get and you will have a lot less "Juice" come out of the blank. Some is going to come out regardless but it will be minimized at the correct temperature.
Click to expand...


So my wife has a kiln for glass work and we own a digital Omega thermocouple. I verified my oven temps and wrapped the Spalted Maple blanks (4" x 4" x 1") in two sheets of Al foil. One leaked out, the other sealed fine, but a large amount of juice cured on the outside of the blank. No big deal, but I will stabilize smaller volumes of wood in the future as to not waste the juice. 

Oh, BTW; Make sure you introduce yourself to our growing community in an Intro Thread. We have a great group of folks here who do all sorts of weird and wonderful things with wood (from tree logging to pen turning). After 5 posts you can begin to PM (if so desired).

Eric


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## TurnTex

Kevin said:


> The juice is not nearly as toxic. Loctite corporation makes the stuff that most of the stabilizers have used for years which is Resinol 90C and supposed to be so dangerous to work with that it can kill you if you aren't extremely cautious. I don't know how accurate that is but I wasn't going to fool with something that's supposed to be that nasty.
> 
> The cactus juice is, I believe a polymer or copolymer with a percentage of CA in it. This is my guess as a part time amateur chemist that still has all his fingers, toes, and eyes. Even eyelashes and eye lids, though they have been singed a few times.



Resinol 90c is chemically similar to Cactus Juice and is not a dangerous chemical. It is very difficult to get, however, since the Henkle Locktite company is not interested in selling to the hobbyist and the price will be similar to my retail price but you will have to buy 4 gallons at a time That is what prompted me to come out with Cactus Juice. I had used some Resinol 90c in the past and was very happy with it but it was almost impossible to get and then if I could, I had to buy at least 4 gallons at cost of $400 shipped. 

I saw a need for smaller quantities for the small shop and found a company that makes a similar product. I did not invent Cactus Juice and do not manufacture it. I buy $3,000 worth at a time and then mix and catalyze it, bottle it, retail it, inventory it, support it, and guarantee it. Even from the company that I buy from, it would cost you $400 for 5 gallons shipped and I sell 5 gallons for $395 plus shipping.

And Cactus Juice does not have any CA in it! It is a proprietary blend of Methacrylate Esters. Here is a link to my MSDS for more information http://www.turntex.com/images/pdf/MSDS.pdf


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## TurnTex

BangleGuy said:


> So my wife has a kiln for glass work and we own a digital Omega thermocouple. I verified my oven temps and wrapped the Spalted Maple blanks (4" x 4" x 1") in two sheets of Al foil. One leaked out, the other sealed fine, but a large amount of juice cured on the outside of the blank. No big deal, but I will stabilize smaller volumes of wood in the future as to not waste the juice.
> Eric



What was the moisture content of your wood? That is the other thing that could cause excess resin to "leak" out. I always dry my blanks in the toaster oven at 200° f for 24 hours before stabilizing to assure they are oven dry (0% moisture). You don't have to go to that extra effort but it does help allow more juice into the wood since there is not any water in the blank taking up space. Remember, air dried wood can only be as dry as EMC (Equilibrium Moisture Content) which in many areas is over 10% moisture and in some cases, 15%, depending on your local humidity. According to an online EMC chart, Grand Junction, CO (closest I could find for you) has a typical EMC of 9.6% for March.


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## BangleGuy

It is true that I didn't oven bake these larger blocks as I was worried about checks and cracks if I dried them out too quickly. I used my meter and I believe the MC checked 12%. Might have been too high, but I wanted to experiment :fool3:.

In general, I take my kd wood and bake for 2 hours at 200F before I stabilize. And yes, I let them cool before putting them in the juice. :i_am_so_happy:

Overall, it has worked very well. I am currently running a 95% RH test on about 10 blanks to determine dimensional stability versus unstabilized wood. After about 200 hours of conditioning (this Saturday), I will take my digital caliper measurements and report some data.


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## Kevin

Curtis, welcome. I was pretty sure we'd be hearing from you once this thread started. 




TurnTex said:


> Kevin said:
> 
> 
> 
> If you want to get close to 30 inches of mercury you'll need a pump like this guys - a two stage pump with at least 5CFM.
> 
> 
> 
> 
> I have to respectfully disagree with you, Kevin. The CFM rating on a vacuum pump does nothing to generate a deeper vacuum, it just gets it there quicker. The large chamber that I make only contain .259 cubic feet of air so the difference between a 1 cfm and 5 cfm pump is going to be negligible. Also, there is going to be a limitation on the CFM that you are able to move through a typical vacuum hose to begin with. To get the best pump for the deepest vacuum, you need to look at the rated vacuum the pump generates. Most HVAC type pumps are rated in microns rather than " Hg. The lower the micron number, the higher the vacuum it will generate. a good pump should be able to pull a 25-50 micron vacuum which is a really deep vacuum.
Click to expand...


I agree with most of what you say, but I was trying to keep things simple. While we know that the micron rating of a pump (at the pump) is the most essential determining factor of how high of a vacuum can be pulled - allthings being ideal - it's not quite as simple as you describe it here either. But this is the very type of discussion I was hoping to avoid. It's kind of like the "240v vs 120v" discussions Grrr!

The reason I used CFMs and specified a 2 stage is because generally speaking unless things have changed in the past 20 years (and they very well may have!) you aren't going to find a cheap, reliable low CFM, low micron pump. If you know of one let us all know I'd love to see our members be able to buy an affordable, dependable, low micron pump and if it is also a low cfm machine that's fine for this purpose because we don't need the volume. 

But frankly, in my opinion the difference between a 20 micron and 40 micron or even 100 micron machine for the purposes of stabilization in wood especially this small, is going to be so negligible that it won't be detecable on the lathe, or to the eye.


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## TurnTex

Kevin said:


> I agree with most of what you say, but I was trying to keep things simple. While we know that the micron rating of a pump (at the pump) is the most essential determining factor of how high of a vacuum can be pulled - allthings being ideal - it's not quite as simple as you describe it here either. But this is the very type of discussion I was hoping to avoid. It's kind of like the "240v vs 120v" discussions Grrr!
> 
> The reason I used CFMs and specified a 2 stage is because generally speaking unless things have changed in the past 20 years (and they very well may have!) you aren't going to find a cheap, reliable low CFM, low micron pump. If you know of one let us all know I'd love to see our members be able to buy an affordable, dependable, low micron pump and if it is also a low cfm machine that's fine for this purpose because we don't need the volume.
> 
> But frankly, in my opinion the difference between a 20 micron and 40 micron or even 100 micron machine for the purposes of stabilization in wood especially this small, is going to be so negligible that it won't be detecable on the lathe, or to the eye.



And I agree with what you say! I agree that the difference between 20 and 100 microns will not be noticeable most likely. However, I get the question all the time of "what is the BEST" etc. And of course, the best, would be the lowest micron you can get, even if it does not make much of a difference.

Especially when we are talking about microns! A 10 micron vacuum at sea level equals a 99.999% vacuum or 29.9196" Hg while a 100 micron vacuum equals a 99.99% vacuum or 29.926" Hg at sea level. Not much of a difference in our application for certain, especially since the other portions of the system will not be nearly that sealed. Heck, even the acrylic that I use in my chamber will allow air through it at super deep vacuum!

I just mentioned the CFM thing since I get folks all the time that get hung up on getting the highest CFM rating and think they need to buy a $400 vacuum pump so they can get 6 CFM thinking it will pull a better vacuum when a lower CFM pump from the same manufacturer will be cheaper and rated to exactly the same vacuum. In that instance, the lower CFM rated pump will be a better deal and not worth spending the extra money on the higher CFM since it will not generate any better vacuum.

And no, there is no such thing as a you aren't going to find a *cheap*, reliable low CFM, low micron pump. But there is such thing as a *cheaper* low CFM, low micron, reliable pump!

For example, JB Industries makes one of the best vacuum pumps out there in my opinion and is made here in the USA. A JB DV4-E 4 CFM pump rated at 25 microns is $100 cheaper than a JB DV6-E pump with the same 25 micron rating.

I am not a fan of the HF pumps simply because they are made in China and are considered a throw away pump since they are not serviceable. Same with the Robinaire Vacu-Master series (red handle). Now, the Roninaire Cool-Tech pumps are US made and are completely re-buildable but they cost more. Same with the JB pumps that I like. They are US made and built like a tank. 

My best advice to anyone is to look at their local pawn shop for a good, American made vacuum pump. I picked up my JB DV6-E, 6 CFM, 25 micron pump like new for $125!


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## BangleGuy

So I have been mentioning that I was doing lots of testing on stabilized wood and I thought I would share a small portion of my data. The data for the following two charts were taken from a single test of stabilized and unstabilized Hard Maple. The purpose of this test was to determine the dimensional effects of humidity on stabilized wood for my metal-core bangle products.

I made 6 samples of hard maple, all 0.75" x 0.75" x 3" with the grain running the 0.75" direction. I chose cross cut samples to maximize the effects of sample growth (in the 3 inch direction). I stabilized 2 samples one time (stabilized x 1), and stabilized 2 samples two times (meaning stabilize/bake/scrape/stabilize/bake/scrape). The twice stabilized blanks are labeled "stabilized x 2". Finally, I did nothing to two samples (baseline). All samples were pre-weighed and measured using a 0.1 gram scale and a digital micrometer to 0.001th of an inch.

(Maple was chosen based on on whole series of tests I've run measuring wood density and dimensional growth due to humidity. This is somewhat of a worst case wood scenario for domestic woods.)

I started out by immersing all the samples in water and placing them under a vacuum (for the first 60 minutes). No vacuum was used for the remainder of the test. Measurements were taken at 10, 25, 40, 60, 130, 250, 1000 and 1500 minutes. 

Conclusions:

Pretest:
The stabilized samples gained about 31% weight (wood plus cured resin weight) during the first stabilization pass. Twice stabilized blanks gained an additional 2.5% for double stabilization. 

Post Test:
The double stabilized samples began to check, crack and bow at around 2 hours into the test. This did not happen on the single-stabilized samples. I believe that during this period of time, the wood structure is failing internally.

The tests did show that a single stabilization pass significantly reduces the effects of moisture on dimensional stability. Obviously, total immersion in water under a vacuum is an extreme test, but it beat having samples in my humidity chamber for 2 months! :wacko1:

Sorry for the dissertation :dash2: and enjoy the wood science! 

(PS, after further review, I found and error in my spreadsheet and I have now corrected the mistake. The biggest change to this post is that my %MC for unstabilized blanks went from 50% to 90%. That is a big error and I felt I should correct this mistake. Just so you all know, I was using the new wet weights for the denominator instead of the starting weight. My bad )

BG

[attachment=4237]
[attachment=4238]
[attachment=26859]


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## Kevin

BangleGuy said:


> ....I think ultimately (days or weeks) the samples will achieve the same moisture content as unstabilized blanks....



If the samples absorb the solids properly this should not be possible. The purpose of stabilization is to replace air pockets in the fiber cells and between cells with solids so moisture absorption is reduced as much as possible. 

How can a stabilized blank absorb as much moisture as an unstabilized one?


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## BangleGuy

Kevin said:


> BangleGuy said:
> 
> 
> 
> ....I think ultimately (days or weeks) the samples will achieve the same moisture content as unstabilized blanks....
> 
> 
> 
> 
> If the samples absorb the solids properly this should not be possible. The purpose of stabilization is to replace air pockets in the fiber cells and between cells with solids so moisture absorption is reduced as much as possible.
> 
> How can a stabilized blank absorb as much moisture as an unstabilized one?
Click to expand...


Kevin, firstly, WB is a great discussion place for all things wood. Thanks to the founders for providing the forum!

I think you are correct. The dried wood structure (which these blanks were oven dried before my test) has been filled by the resin to 'near capacity'. As the moisture works its way in, wood growth causes the overall sample density to increase. The resin (similar to all plastics and other porous materials) will also take on some level of moisture over time. It is interesting that all of these blanks sank to the bottom of the water container at the end of the test. This would indicate that the blank volume was heavier than water... When I get home later today, I will post sample density for each specimen (weight / l x w xh). (This will drive Cody crazy because my units will be grams per cubic inch!!!:dash2: See Cody, us yanks can use metric sometimes!!! )

This is all very interesting, and hopefully useful to others besides me :wacko1:


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## Kevin

I know virtually all materials are hygroscopic to *some* degree, and I stand to be corrected, but I do not believe the resins used for stabilizing can absorb moisture to any measurable degree with thew instruments available to us. 

If stabilized wood could absorb the same amount of moisture as unstabilized, what would be the point in stabilizing at all? 


:scratch_one-s_head:


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## davidgiul

A fascinating and informative discussion on wood stabilizing. 

On the subject of vacuum pumps, I would never buy anything from HF. Check pump companies that supply the HVAC guys with their pumps. They use the pumps to evacuate all moisture from the lines that work with air conditioners.

I was under the impression that there are many species of wood that are extremely resistant to preservative treatment because of low permeability such as Teak, Walnut, Wenge, etc.

I do not see how a wood that has been filled with cactus juice can reach an ambient MC. The resin fills the pores of the stabilized wood thus allowing no place for moisture


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## BangleGuy

davidgiul said:


> A fascinating and informative discussion on wood stabilizing.
> 
> On the subject of vacuum pumps, I would never buy anything from HF. Check pump companies that supply the HVAC guys with their pumps. They use the pumps to evacuate all moisture from the lines that work with air conditioners.
> 
> I was under the impression that there are many species of wood that are extremely resistant to preservative treatment because of low permeability such as Teak, Walnut, Wenge, etc.
> 
> I do not see how a wood that has been filled with cactus juice can reach an ambient MC. The resin fills the pores of the stabilized wood thus allowing no place for moisture



David, I have done humidity testing on stabilized and non-stabilized Purpleheart, Leopardwood and Bocote. I will work on publishing some of this data next. Since these tests were done in a humidity chamber, the MC gain is much slower than in my water immersion tests.

It is interesting to note that the stabilized x 2 test samples gained more MC than the x 1 samples. This could be because of the checking and cracking that occurred in the samples...

I also have MC and dimensional data for 32 different species of wood when exposed to 90%RH over time. If anyone out there is interested in a particular species, just let me know.


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## BangleGuy

Kevin said:


> If stabilized wood could absorb the same amount of moisture as unstabilized, what would be the point in stabilizing at all?
> 
> :scratch_one-s_head:



For most pen turners, I don't think moisture resistance is really the point of stabilizing. It is more for making soft/punky woods hard, turnable without tear-out and allows for the wood to be polished to a high sheen. The fact that a thin unstabilized pen made in Arizona grows by 0.005" OD in Florida really doesn't matter to the user, or the function, of the pen... and remember that this test was total immersion, if you drop your knife / new ballpoint pen in water for 24 hours (+1 hour under vacuum), you will probably be unhappy with the result.


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## Kevin

Okay lets say stabilized wood absorbs moisture. It has to be between the threads of cells which make up the fibers. If the cells themselves are being filled with the resin, where the bound water used to be, the cells themselves must be impervious to water absorption. 

So if the wood can absorb mositure where the free water used to be, whie this may be unwanted, the wood would still be mush less suscpetible to mositure damage. Where the heck is Curtis - Curtis get your fanny in here and educate us!


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## BangleGuy

Here is a plot of %MC vs time for Maple, Purpleheart, Leopardwood and Bocote samples which were both stabilized and unstabilized. The samples were placed in a humidity chamber with 90%RH for 170 hours. In each case, except Bocote, the stabilized blanks performed better. The difference between Bocote samples was insignificant. 

[attachment=3617]


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## davidgiul

BangleGuy said:


> Here is a plot of %MC vs time for Maple, Purpleheart, Leopardwood and Bocote samples which were both stabilized and unstabilized. The samples were placed in a humidity chamber with 90%RH for 170 hours. In each case, except Bocote, the stabilized blanks performed better. The difference between Bocote samples was insignificant.


Bangleguy, 
The graph is well done and I enjoy the fruits of your research. It shows me several things:
1) Some species of wood are impervious to treatment.
2) Wood will reach an equilibrium with its' environment even if it is kiln dried to 6-8% MC regardless of the treatment.

Dave


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## Kevin

I couldn't stand it. I went to WSSI's site and found the answer. Makes sense to me, and validates my last guess about where the water is being absorbed, and where it isn't. This is what I felt was the most relevant part . . . 


_...Stabilized wood will take in moisture by capillary action much like steel wool is waterproof but will absorb water like a sponge. If you put a block of stabilized wood in water, it will become saturated in a few hours. The actual fibers are dry but the spaces will pick up moisture. If you lay the wood on a workbench, the water will leak out overnight and the piece will be dry again tomorrow...
_


This is the page I took the quote from. It doesn't answer everything but it solves the issue enough for me. 





.


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## BangleGuy

Here is a good article on water repellency and wood stability put together by the US Forest Service. I am still working my way through the information, but the paper covers the subject well.

[attachment=3630]


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## BangleGuy

Here is the latest plot from this weekends stabilizing. Just to keep the thread going :wacko1: (Oh, the Ebony is Macassar, And there is no point in stabilizing African Blackwood or Cocobolo as they are like Kingwood in not gaining weight, and the internal oils don't mix well with the resin. ) Enjoy.

[attachment=3822]
[attachment=3823]


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## TurnTex

BangleGuy said:


> Here is the latest plot from this weekends stabilizing. Just to keep the thread going :wacko1: (Oh, the Ebony is Macassar, And there is no point in stabilizing African Blackwood or Cocobolo as they are like Kingwood in not gaining weight, and the internal oils don't mix well with the resin. ) Enjoy.



Looks about what I would expect on the denser woods. I have done a lot of testing with Texas woods but not any of the exotics. Are you really only getting a 50+% increase in weight on the spalted maple? I have other customers who are reporting as much as a 300% weight gain on spalted maple. I have not done spalted maple since it is not native here but I have done a lot of spalted hackberry and spalted pecan and both of those are almost always over a 100% weight gain.

What were your beginning and ending weights?


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## davidgiul

BangleGuy said:


> Here is the latest plot from this weekends stabilizing. Just to keep the thread going :wacko1: (Oh, the Ebony is Macassar, And there is no point in stabilizing African Blackwood or Cocobolo as they are like Kingwood in not gaining weight, and the internal oils don't mix well with the resin. ) Enjoy.


Bangleguy has shown in his graphs that some woods do not absorb any stabilizing agents. I often read about "stabilized" knife scales and pen blanks for exotic woods that are impervious to treatments. Maybe I am wrong, but it seems that trying to stabilize a wood that is listed as impervious is a waste of money and is an advertising gimmick unless the wood has gone punk. Any thoughts on this observation?

Dave


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## jxmcguire1

BangleGuy said:


> Here is a good article on water repellency and wood stability put together by the US Forest Service. I am still working my way through the information, but the paper covers the subject well.



Downloaded the publication and read about half way through. As soon as I finish, guess the next thing is to go through again, a little slower, try some of the formulae to see if it makes sense to me. I suspect that the multiple absorbancy mechanisms at play are dominant causes in different regimes or conditions, and that the range of conditions for some of the effects to occur will seldom occur in the fine woodworking field. I'll probably have to get my eyes on some of the listed reference documents to actually have a little confidence in my view of it though.

I'm playing with a digital camera now with a microscope to see if the pictures reveal anything useful about the microstructures (grain, curl, pore spaces, and such) in different species of wood. I think it would be interesting and maybe informative to look at thin sections of different woods, with and without resin stabilization, especially to see the depth and extent of pore filling under different treatment conditions.


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## BangleGuy

davidgiul said:


> BangleGuy said:
> 
> 
> 
> Here is the latest plot from this weekends stabilizing. Just to keep the thread going :wacko1: (Oh, the Ebony is Macassar, And there is no point in stabilizing African Blackwood or Cocobolo as they are like Kingwood in not gaining weight, and the internal oils don't mix well with the resin. ) Enjoy.
> 
> 
> 
> Bangleguy has shown in his graphs that some woods do not absorb any stabilizing agents. I often read about "stabilized" knife scales and pen blanks for exotic woods that are impervious to treatments. Maybe I am wrong, but it seems that trying to stabilize a wood that is listed as impervious is a waste of money and is an advertising gimmick unless the wood has gone punk. Any thoughts on this observation?
> 
> Dave
Click to expand...


Dave, I actually fudged my data for the Kingwood as the measurements indicated the samples actually lost 0.1% weight! This may be a scale accuracy thing though, so I altered the data slightly (-0.1% to + 0.1%). I will post my actual weights tonight. 

The Kingwood really could have lost weight as there was a significant amount of purple tree oil coming out of the wood during the vacuum process (making my cactus juice purple). All of my samples (bangle blanks) were baked at 200F for two hours prior to stabilizing. Interesting to note that the Kingwood and Cocobolo had tree resin (sap) seeping from pores and dried on the surface of the wood (after the pre-bake step). I scraped this dried stuff off prior to stabilizing.

Next on my list is to cure a cup of cactus juice and run a water absorption test on dried resin alone. My guess is that the resin will gain weight too (just as all plastics are somewhat porous). We need to remember that a water molecule is only 2.75 angstroms in diameter! That is SMALL! :wacko1:

In an earlier post, Rick talked about adding Japan drier to his stabilizing of Cocobolo. In all of my tests, Cocobolo has shown to be extremely dimensionally stable and not really needing to be stabilized. I would add African Blackwood and Bocote to this list. Jury is still out on Kingwood. 

More to come...


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## BangleGuy

TurnTex said:


> BangleGuy said:
> 
> 
> 
> Here is the latest plot from this weekends stabilizing. Just to keep the thread going :wacko1: (Oh, the Ebony is Macassar, And there is no point in stabilizing African Blackwood or Cocobolo as they are like Kingwood in not gaining weight, and the internal oils don't mix well with the resin. ) Enjoy.
> 
> 
> 
> 
> Looks about what I would expect on the denser woods. I have done a lot of testing with Texas woods but not any of the exotics. Are you really only getting a 50+% increase in weight on the spalted maple? I have other customers who are reporting as much as a 300% weight gain on spalted maple. I have not done spalted maple since it is not native here but I have done a lot of spalted hackberry and spalted pecan and both of those are almost always over a 100% weight gain.
> 
> What were your beginning and ending weights?
Click to expand...

 Curtis, I reviewed the numbers and I had an error which I corrected in the plot. The Spalted Maple is over 100%. Thanks.


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## brown down

i contacted curtis last night, what a great guy to talk to and very very informative, prior to reading this thread! unfortunately i need a larger capacity vacuum chamber and wonder if anyone has any thought as to this design, pressure cooker converted to a vacuum chamber??? that way i can fit bowl size pieces in the chamber? any thoughts
http://thegreatgeekery.blogspot.com/2011/05/pressure-cooker-vacuum-chamber.html


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## BangleGuy

brown down said:


> i contacted curtis last night, what a great guy to talk to and very very informative, prior to reading this thread! unfortunately i need a larger capacity vacuum chamber and wonder if anyone has any thought as to this design, pressure cooker converted to a vacuum chamber??? that way i can fit bowl size pieces in the chamber? any thoughts
> http://thegreatgeekery.blogspot.com/2011/05/pressure-cooker-vacuum-chamber.html



There are some ebay postings for vacuum chambers that look interesting too...

http://www.ebay.com/itm/Vacuum-chamber-VAC-IT-PRO-degasing-urethanes-etc-/190668175608?pt=BI_Pumps&hash=item2c64b578f8#ht_2339wt_924


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## brown down

BangleGuy said:


> brown down said:
> 
> 
> 
> i contacted curtis last night, what a great guy to talk to and very very informative, prior to reading this thread! unfortunately i need a larger capacity vacuum chamber and wonder if anyone has any thought as to this design, pressure cooker converted to a vacuum chamber??? that way i can fit bowl size pieces in the chamber? any thoughts
> http://thegreatgeekery.blogspot.com/2011/05/pressure-cooker-vacuum-chamber.html
> 
> 
> 
> 
> There are some ebay postings for vacuum chambers that look interesting too...
> 
> http://www.ebay.com/itm/Vacuum-chamber-VAC-IT-PRO-degasing-urethanes-etc-/190668175608?pt=BI_Pumps&hash=item2c64b578f8#ht_2339wt_924
Click to expand...

you ARE THE MAN! I just ordered it and hopefully comes soon! thats exactly the size i needed and now don't have to go through all of the BS of making one or rigging one that don't know if it would work. plus a pressure cooker cost just around the same price. thank you so much for helping me out.

Reactions: +Karma 1


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## BangleGuy

brown down said:


> BangleGuy said:
> 
> 
> 
> 
> 
> brown down said:
> 
> 
> 
> i contacted curtis last night, what a great guy to talk to and very very informative, prior to reading this thread! unfortunately i need a larger capacity vacuum chamber and wonder if anyone has any thought as to this design, pressure cooker converted to a vacuum chamber??? that way i can fit bowl size pieces in the chamber? any thoughts
> http://thegreatgeekery.blogspot.com/2011/05/pressure-cooker-vacuum-chamber.html
> 
> 
> 
> 
> There are some ebay postings for vacuum chambers that look interesting too...
> 
> http://www.ebay.com/itm/Vacuum-chamber-VAC-IT-PRO-degasing-urethanes-etc-/190668175608?pt=BI_Pumps&hash=item2c64b578f8#ht_2339wt_924
> 
> Click to expand...
> 
> you ARE THE MAN! I just ordered it and hopefully comes soon! thats exactly the size i needed and now don't have to go through all of the BS of making one or rigging one that don't know if it would work. plus a pressure cooker cost just around the same price. thank you so much for helping me out.
Click to expand...


Well, I hope it works out for you. I had searched Ebay in the past for some chambers and decided on the Turntex model. 

Also, I have used the Turntex Cactus Juice for about a month, stabilizing over 100 different bangle blanks (and 20 different wood species). The juice works well. Just don't do too much stabilizing in the house at one time or you'll gas yourself out!:wacko1: It's worth every penny to buy a toaster oven at Walmart or Lowes and leave it in the shop (just check your oven termp at 200 F) Good Luck!


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## brown down

BangleGuy said:


> brown down said:
> 
> 
> 
> 
> 
> BangleGuy said:
> 
> 
> 
> 
> 
> brown down said:
> 
> 
> 
> i contacted curtis last night, what a great guy to talk to and very very informative, prior to reading this thread! unfortunately i need a larger capacity vacuum chamber and wonder if anyone has any thought as to this design, pressure cooker converted to a vacuum chamber??? that way i can fit bowl size pieces in the chamber? any thoughts
> http://thegreatgeekery.blogspot.com/2011/05/pressure-cooker-vacuum-chamber.html
> 
> 
> 
> 
> There are some ebay postings for vacuum chambers that look interesting too...
> 
> http://www.ebay.com/itm/Vacuum-chamber-VAC-IT-PRO-degasing-urethanes-etc-/190668175608?pt=BI_Pumps&hash=item2c64b578f8#ht_2339wt_924
> 
> Click to expand...
> 
> you ARE THE MAN! I just ordered it and hopefully comes soon! thats exactly the size i needed and now don't have to go through all of the BS of making one or rigging one that don't know if it would work. plus a pressure cooker cost just around the same price. thank you so much for helping me out.
> 
> Click to expand...
> 
> 
> Well, I hope it works out for you. I had searched Ebay in the past for some chambers and decided on the Turntex model.
> 
> Also, I have used the Turntex Cactus Juice for about a month, stabilizing over 100 different bangle blanks (and 20 different wood species). The juice works well. Just don't do too much stabilizing in the house at one time or you'll gas yourself out!:wacko1: It's worth every penny to buy a toaster oven at Walmart or Lowes and leave it in the shop (just check your oven termp at 200 F) Good Luck!
Click to expand...

I talked to him the other day, what a great guy. I just need to find out if the cactus juice is food safe. I want to suck that stuff or another type through my bowls and pepper mill blanks to add a solid finish through the pieces but have to be 100% sure it is food grade safe. and also to save and stabilize wood i would normally burn! thanks again for getting me that info:clapping::clapping:


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## ripjack13

I'd like to know if it is food safe as well. I was thinking of glueing up some stabilized blocks into a bread board. (not for cutting on though) I think that would make great use of my scrap blocks I have accumulated over the years.


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## Mizer

ripjack13 said:


> I'd like to know if it is food safe as well. I was thinking of glueing up some stabilized blocks into a bread board. (not for cutting on though) I think that would make great use of my scrap blocks I have accumulated over the years.


That is what I was wondering also. Other than the food safe question, which I would imagine it is. I was wondering how wood that has been stabilized glues.


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## BangleGuy

Mizer said:


> ripjack13 said:
> 
> 
> 
> I'd like to know if it is food safe as well. I was thinking of glueing up some stabilized blocks into a bread board. (not for cutting on though) I think that would make great use of my scrap blocks I have accumulated over the years.
> 
> 
> 
> That is what I was wondering also. Other than the food safe question, which I would imagine it is. I was wondering how wood that has been stabilized glues.
Click to expand...


I have not researched if the cured resin is food safe... It would be a good question for Curtis of Turntex.

Regarding how it glues, I have glued stabilized pieces together just fine using Gorilla glue and two part epoxy.


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## ripjack13

Gorilla glue and epoxy....which one held up the longest?

And...specifically which GG did you use? The white or the brown? I have both.


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## BangleGuy

ripjack13 said:


> Gorilla glue and epoxy....which one held up the longest?
> 
> And...specifically which GG did you use? The white or the brown? I have both.



I used the brown GG in one instance where a tan/brown seem was acceptable. In another instance (where a brown line wasn't going to work), I used two-part clear epoxy. They both seemed to hold up fine. I prefer the GG since it doesn't require mixing.


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## TurnTex

I am sorry for reviving an old thread but am just now trying to get caught up on the various forums I visit! I saw the question about food safe and Cactus Juice.

I can not claim that Cactus Juice is food safe. in order to do so, certain FDA tests would have to be done which would be cost prohibitive so, the answer is NO, it is not listed as food safe. However, once cured, Cactus Juice is an acrylic similar to Plexiglas.


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## healeydays

I just found this old link. Good info in here too.


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## hobbit-hut

Wow, what a great thred !!! I'm sure now I'm going to give this a try. Some of you guys are so inteligent makes me want to go read a book. I can't even find spellcheck. But I think I'll try to post a few photos first. I don't know if it would require a new thred or be ok on this one but I have seen pressure pots mentioned also. I was wondering is that something used in congunction with the vacume process to achive an end, or a totaly different method to get a simular result ?


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## BangleGuy

hobbit-hut said:


> Wow, what a great thred !!! I'm sure now I'm going to give this a try. Some of you guys are so inteligent makes me want to go read a book. I can't even find spellcheck. But I think I'll try to post a few photos first. I don't know if it would require a new thred or be ok on this one but I have seen pressure pots mentioned also. I was wondering is that something used in congunction with the vacume process to achive an end, or a totaly different method to get a simular result ?



Vacuum is used to evacuate most of the air from the wood and replace the void space with a resin system. The resin used for this process penetrates the pores of the wood since it is very thin (low viscosity). This process works well for making the wood structure more stable/harder and easier to turn. It also provides a lot more protection and dimensional stability to the wood structure when exposed to moisture. (The down side is that it will fill pores of wood that you might want to fill with other, more interesting materials such as minerals or epoxies.) Lastly, some very dense woods do not accept stabilization as they are either too oily or do not have much void space to fill (i.e. Desert Ironwood). 

A pressure pot takes the opposite approach and generally is used to force highly viscous epoxy mixtures into the outer pores of the wood. The pressure shrinks air bubbles and helps with penetration. In this system, the inner pores of the wood are not filled with epoxy (unless the wood is REALLY porous like a sponge).

It is possible to pressure pot epoxies onto the wood and then stabilize the wood afterward, although most people don't do that very often. So, the decision to use pressure or vacuum really depends on what you are trying to accomplish


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## hobbit-hut

Yes you are very clear in your answer. You must have been a teacher or a natural born edducator. I actualy discovered the Presure method in a limited way about 10 years ago. I made an instrument and put it in a pvc tube full of tung oil with cap on tight and set it by a heater thinking I would warm it up and maybe that would help to soak up the oil. After a few hours the cap blew off. So I thought what the heck and I drilled a hole in the cap and put a tube in it and set a ball bering on the tube. The next day when I took the instrument out and dried it off it just kept leaking the oil out and I would have to keep wipeing every few hours. There was one part that was solid wood all the way through, about an inch and a half. So I cut it open to see if the oil had penatrated to the center . To my suprise it had. So I contuned to do that with all the instruments I used an oil finish on.


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## Steelart99

Just to add my small amount of info to this thread and to clarify the process of vacuum stabilization. 

When you pull a vacuum you are removing the air from the wood, then as you remove the vacuum, it is the outside air pressure (at 14.7 psi) that is pushing the stabilizing material into the wood and into the spaces where the air was. A perfect vacuum is not needed, but more is better. So, you put the wood in, pull a vacuum and watch the bubbles (air being pulled out), release the vacuum which THEN drives the stabilizer into the wood (external air pressure), repeat the vacuum cycle which should show far fewer or no bubbles and again release the vacuum driving stabilizer into the wood. Repeat if you feel it is needed.

It is also very helpful (darn near required) to have the wood held under the surface of the stabilizing agent so that it is surrounded and the air pressure pushes on the liquid driving it into the wood from all sides (not just pushing air back in). 

Now, if you had a vacuum/pressure chamber, you could even add additional air pressure, controlled so that you don't exceed its capability, to drive the liquid into the wood even more. Obviously, there is a saturation point at which no more liquid can be driven in. Adding pressure is helpful for large blanks, or dense blanks, but does not seem to be needed for smaller/less dense blocks. I've usually limited my added air pressure to under 30 psi. 

The point here is that while the piece is under vacuum, it is not really absorbing a lot of stabilizer. You are just removing the air from the wood. It is the process of removing the vacuum and letting the air back into the chamber that actually provides the external pressure to force the stabilizer into the wood.

My take on the process ... 

Dan


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