Vacuum and pressure

Shane.M

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My question is after vacuuming all the air bubbles out instead of using a soak process would it benefit the penetration of the stablizing resin to put it a pressure pot under 50 psi? If so how long would you leave it under pressure? Thank you
 

gman2431

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Yes it helps a lot. Some guys pressure them and leave to soak.
 

Shane.M

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So I have 2 blocks in the vacuum pot right now. The were under vacuum for 23 hours, then the vacuum was released and will soak for 24 hours. Then planing on running a 50 pound pressure cycle. How long under 50 pounds of pressure would you think?
 

gman2431

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Haven't done it yet personally but I think @chanser123 does.

After vacuum I soak for 3 days or more so I would see myself pressurizing it and just leaving it.
 

Sprung

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Sorry, Tony, I can't help here. I've heard of people doing pressure after vacuum, but I don't have the equipment to try it myself. I pull vacuum and then, after vacuum has been released, let it soak for at least double the time it was under vacuum.
 

Shane.M

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Thanks for the response guys. I will be putting th first batch in the pressure tank tomorrow to start my research.
 

rocky1

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My question is after vacuuming all the air bubbles out instead of using a soak process would it benefit the penetration of the stablizing resin to put it a pressure pot under 50 psi? If so how long would you leave it under pressure? Thank you

Shane, it's entirely possible to stabilize wood without either vacuum or pressure, all either does is accelerate the saturation process; vacuum by removing the air from the piece, allowing the resin to soak in quicker; pressure by forcing the resin into any voids in the structure of the wood, pushing the air out.

"Would it benefit penetration of the stablizing resin to put it in a pressure pot under 50 psi?"

- Yes... it will force the resin into the wood faster than simple soaking.
- Yes... it will penetrate deeper, in a shorter amount of time.
- NO... you cannot force more resin into the piece than it is capable of holding. See above two lines.

The structure of the wood only has so much capacity to hold resin, you can't put any more in there once you reach the point of saturation. (For the professors in the crowd - According to the laws of physics... Yes, the saturation point does increase slightly under pressure, but unless your oven is under pressure, what little extra you manage to force in there is going to seep out after you remove it from pressure to cook it.)

Bottom line is, all you're doing is reducing the amount of time you need to soak after vacuum. That's your only benefit.


So I have 2 blocks in the vacuum pot right now. The were under vacuum for 23 hours, then the vacuum was released and will soak for 24 hours. Then planing on running a 50 pound pressure cycle. How long under 50 pounds of pressure would you think?

Depends totally upon size and density of the blocks. If they're pen blanks 24 hours should be more than adequate. If they're call blanks, it's very possible that's adequate. Depends totally upon how thoroughly the resin penetrated under vacuum and soak.

Personally, I ran it both ways - vacuum, soak, and pressure cycle. And vacuum, pressure cycle, and soak.

I really haven't seen a lot of benefit in it either way, other than the potential to reduce soak time. My blanks didn't appear any different, didn't feel any heavier, although I didn't weigh any of them to determine if there was any minute difference. I did see more resin cook out of my blanks when running pressure last however.

Most of the time I throw stuff in the vacuum pot and let it soak up to a week, (unless I'm first round trying to dye it). Typically, I'll leave it sit in my vacuum pot, and I may pull vacuum on it 5 - 6 times while it soaks. Have left it under vacuum up to a week, and vacuumed, bled vacuum off, and pulled it down again repeatedly. I seldom see a blank float when I'm done. If it's dense enough to sink to begin with, it probably isn't going to take much resin no matter what you do to it.

Thanks for the response guys. I will be putting the first batch in the pressure tank tomorrow to start my research.

Again, how long you leave it Shane is dependent upon size of the blanks, and how dense they are. Somewhere in the 24 - 48 hour range should be more than adequate.
 

Shane.M

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Thank you rocky1 I appreciate the help and info. I will have the set of blanks headed to the oven in about 30 minutes. One is a Burl blank 6"x3"x1-1/2. The other is a sinker cypress blank 3x3x1-1/2
 

rocky1

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Should still be OK with 24 hours Shane, you're only penetrating 1 1/2".

The sinker cypress should have been pretty dense and probably didn't take much resin regardless, pressure may have helped that one, definitely worth a shot anyhow. The Burl blank depends upon what it is. I had two or three different burls I've tried that didn't soak up much in 2 weeks. Box Elder Burl acts like a sponge. Set a 1 1/2" x 1 1/2" x 3" blank in a dish with a little over 1/4" cactus juice and a whole lot of orange dye, and left it sitting on the counter Thursday night just to see how far it would soak it up without vacuum, playing mostly... Want to double dye it and I didn't want a lot of penetration. I came home from work Friday evening, the entire blank is solid orange! :whatever:
 

Shane.M

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Oh wow. I took both blanks out of the oven earlier. Will and them down and see what I end up with. Hey what are your thoughts on the picture. Any idea how to achieve something like this.

FB_IMG_1493521354046.jpg
 

rocky1

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You need to talk to Norm or Matt there! I have no clue how you get that many colors in there. Hell, I don't have that many colors!!
 

StacyWhetzell

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Shane, can you explain, "cooking" after soaking.
I understand the soaking (under negative pressure, atmospheric pressure and 50 lb pressure, etc).
But what is the cooking for?
Is it just you accelerate the drying process?
What temp, how long?
Are ther links on this site to a "from start to finish" about stabilizing wood?
Thanks much to all who can offer advice
Stacy
 
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rocky1

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Once you saturate the wood with the stabilizing resin Stacy, it has to be cooked to activate it, and cause it to harden.

Most resins recommend wrapping the blanks in aluminum foil and cooking at 200 or so degrees for 1 to 2 hours, most folks have found that cooking at 180 - 185 degrees unwrapped with a foil lined drip pan in the bottom of the oven results in a much cleaner stabilized blank. Doesn't require nearly as much sanding!!

Step by step, start to finish is covered here...

https://www.turntex.com/component/content/article?id=60:using-mesquitemans-cactus-juice&catid=35
 

John Mikulski

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I'm just now experimenting with stabilizing with dye and am finding it soooooo hard to wait.. Has anyone quantified how much time can be reduced if using pressure once the vacuum is released? Also, not many are willing to share the double dye technique.. I'm guessing because many make good money and are afraid of creating competition.
 

Sprung

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I'm just now experimenting with stabilizing with dye and am finding it soooooo hard to wait.. Has anyone quantified how much time can be reduced if using pressure once the vacuum is released? Also, not many are willing to share the double dye technique.. I'm guessing because many make good money and are afraid of creating competition.

John, poke around in this sub-section of the forum. I, and I'm sure others, have spoken on double dyeing. However, double dyeing is part science and part art. There are some things you just have to figure out on your own that are things you have to learn a feel for. Like, how long to soak a specific piece of wood. That length of time can vary within even the same species. With time you can look at a piece of Boxelder Burl and say that this one piece needs to only soak for a few minutes and then look at another piece and say that it needs to soak overnight - stuff like that is something you can't really learn from reading, but have to learn by doing and experimenting. Poke around in threads in here and, if you've got any questions, ask - I and others are always happy to help. But also understand that there are some things, like double dyeing techniques, that we might speak on and even tell the how, but will have components that one simply has to figure out for themselves and/or develop a feel for, especially since it's part art form.

Also, take notes on what you're doing - if you have a result that you really like and want to reproduce, your notes will be valuable. I spent months a while ago trying to develop a really good lime green (before TurnTex sold one) and finally found a mix of dyes I liked. I liked it even better than the lime green TurnTex sells, that they released about the time I figured mine out. Bad part is, I never wrote any of it down in the process of developing it, so even with attempting it again, I have been unable to reproduce that exact shade of lime green again. What a shame, because it was spectacular...

As far as pressure, I haven't tried it. Supposedly it does reduce the soak time after vacuum by some. But, IMO, this is one area of woodworking where being patient pays off in better results.
 

rocky1

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Personally, I soak mine under vacuum, my vacuum chamber will hold vacuum, much better than my pressure pot will hold pressure. In stabilizing, either is simply a tool to speed the "wait" process. I'm pretty patient, procrastinate or forget to pull things and cook them off. Speaking of which I have some spalted pecan blanks that have been soaking since, oh... February I think! They should be stable when I cook them!! :lol2:
 

John Mikulski

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My first double dye batch:

Red first soak no vacuum.. 12 hours under 90lbs pressure.

Baked/sanded

Purple full vacuum 3 hours.. 12 hours under 90lbs of pressure.

Baked/sanded

BE3AD440-42BD-46AA-B429-A079363742A4.jpeg
 

jasonb

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Looks Great!
and
Wow, 90lbs of pressure. That must be one heck of a pressure pot.
 
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