Laboratory vacuum oven for wood stabilizing?

JMC503

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Hello! I’m wondering if anybody has used a laboratory vacuum oven for stabilizing? I have one, but every time I search the web with this specific question I get no results. I have a VWR 1430M. I am brand new to this stabilizing game. Just bought my first cactus juice. Any tips or tricks or experiences with using a vacuum oven for this application would be greatly appreciated. Clearly I will pull vacuum first with no heat to saturate the wood, but once saturated and removed from the cactus juice bath, can I also cure it under vacuum pressure, so as to retain as much saturation as possible? The boiling point of liquids is reduced greatly in a vacuum, so my concern is to not overcook the resin or create an unsafe situation. Somebody has to have done this before! Thank you in advance.
 

DLJeffs

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When stabilizing, the resin penetrates into the pores of the wood after the air has been sucked out by the vacuum. The wood, being submerged, has no choice but to fill those voids with resin. But that only happens when you release the vacuum and the wood/resin is submitted to atmospheric pressure again. It's that pressure that drives the resin into the wood. So that step needs to be in your process, no matter how you cure the resin afterwards. The speed at which the resin can penetrate into the voids is a function of the porosity of the wood. In most cases, it takes a lot longer for the resin to fill the voids than it took to vacuum all the air out of the voids. Typically, Turn Tex recommends your soak period be at least twice as long as the duration of your vacuum period. Lastly, most liquids boil at lower temperatures when the pressure is reduced. Similarly, most chemical reactions occur faster as temperature increases (two part epoxy cures much faster if you warm up the resin and hardener first). So curing the stabilizing resin under vacuum might work but could also be problematic. If the resin cures too fast, you could trap uncured resin inside cured resin. You'd also get more bleed out which means less resin impregnated into the wood. In my opinion, curing your wood under vacuum would serve no purpose. Curtis at Turn Tex is a wealth of knowledge on stabilizing and is usually very responsive to questions.
 

Greenacres2

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I use a lab vacuum oven to cure CJ, but when curing i clamp the door mostly closed (use a clamp to hold it loose) to allow vapors to escape. I'm thinking (not based on science) is that trying to cure under vacuum might actually draw the resin out of the wood. Seems like one would nearly need to keep the blank(s) submerged and cure the whole container if using vacuum while curing. While i still get some push-out of juice with the lab oven, it's a much smaller amount...kitchen toaster oven chambers can continue their heat rise after the heating element shuts down. Can (and did) cause a fire with your wood, fortunately my detached garage did not burn with the buckeye burl.

I do use my vacuum oven when drying to prepare for putting it in CJ. I pull the vacuum and then turn the heat on, but isolate from the vac pump before hitting 70 F so i don't draw moisture into the pump. With the brick mass, it takes the lab oven a while to heat up, but is very stable once heated. Infinitely safer than the fire risk that a toaster oven poses. In my experience, a dental lab oven (no vacuum) would have been just as good, but the old vac oven came up on the auction site for $50 and was only 15 miles away (shipping would be in the $75-$100 range from a private seller today). Another potential advantage to a dental lab oven is that they are much more common to find used in smaller communities--just check with your dentist or oral surgeon to see who they use to make dentures!!

Good luck!!
 

2feathers Creative Making

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Your vacuum will most likely hinder the actual cure. I would do as described and find a way to eliminate the vacuum part of the system when cooking the blanks.
The vacuum oven should be a huge plus in the steps leading up to the cooking though.
If you can find a way to trap the water that is being removed, you have a small vacuum kiln that will speed up the drying of the blanks prior to actual stabilization.
 

JMC503

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When stabilizing, the resin penetrates into the pores of the wood after the air has been sucked out by the vacuum. The wood, being submerged, has no choice but to fill those voids with resin. But that only happens when you release the vacuum and the wood/resin is submitted to atmospheric pressure again. It's that pressure that drives the resin into the wood. So that step needs to be in your process, no matter how you cure the resin afterwards. The speed at which the resin can penetrate into the voids is a function of the porosity of the wood. In most cases, it takes a lot longer for the resin to fill the voids than it took to vacuum all the air out of the voids. Typically, Turn Tex recommends your soak period be at least twice as long as the duration of your vacuum period. Lastly, most liquids boil at lower temperatures when the pressure is reduced. Similarly, most chemical reactions occur faster as temperature increases (two part epoxy cures much faster if you warm up the resin and hardener first). So curing the stabilizing resin under vacuum might work but could also be problematic. If the resin cures too fast, you could trap uncured resin inside cured resin. You'd also get more bleed out which means less resin impregnated into the wood. In my opinion, curing your wood under vacuum would serve no purpose. Curtis at Turn Tex is a wealth of knowledge on stabilizing and is usually very responsive to questions.
Thank you DLJeffs This is exactly the information I was looking for (thanks for pointing out my harebrained lack of foresight with curing under vacuum, it is truly counterintuitive). I’m not trying to reinvent the wheel. I have a decent idea of how vacuum oven works, and a healthy respect for Asking as many questions as it takes and reading as much as possible and bugging anybody that will listen before I do most things that could end badly. My wife might say different lol

thanks again,

JMC
 

JMC503

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Your vacuum will most likely hinder the actual cure. I would do as described and find a way to eliminate the vacuum part of the system when cooking the blanks.
The vacuum oven should be a huge plus in the steps leading up to the cooking though.
If you can find a way to trap the water that is being removed, you have a small vacuum kiln that will speed up the drying of the blanks prior to actual stabilization.
2feathers,

Thank you so much for your insight. After giving it five seconds of real thought, I decided that it may be one of the dumbest ideas ever to suck the pores dry while trying to fill them up. A quick stroke of genius! I use vacuum pumps almost daily, and if I am going to introduce a significant amount of water vapor, solvent vapor, or anything bad for pump I use a cold trap inline between pump and pressure vessel to condense vapor. I also filter or change the pump oil after every use.
You have no idea how exciting this is to me to interact with people who can identify with the idea of what I am talking about. I have never joined a forum or social media or anything else besides my local next-door app
 

JMC503

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I use a lab vacuum oven to cure CJ, but when curing i clamp the door mostly closed (use a clamp to hold it loose) to allow vapors to escape. I'm thinking (not based on science) is that trying to cure under vacuum might actually draw the resin out of the wood. Seems like one would nearly need to keep the blank(s) submerged and cure the whole container if using vacuum while curing. While i still get some push-out of juice with the lab oven, it's a much smaller amount...kitchen toaster oven chambers can continue their heat rise after the heating element shuts down. Can (and did) cause a fire with your wood, fortunately my detached garage did not burn with the buckeye burl.

I do use my vacuum oven when drying to prepare for putting it in CJ. I pull the vacuum and then turn the heat on, but isolate from the vac pump before hitting 70 F so i don't draw moisture into the pump. With the brick mass, it takes the lab oven a while to heat up, but is very stable once heated. Infinitely safer than the fire risk that a toaster oven poses. In my experience, a dental lab oven (no vacuum) would have been just as good, but the old vac oven came up on the auction site for $50 and was only 15 miles away (shipping would be in the $75-$100 range from a private seller today). Another potential advantage to a dental lab oven is that they are much more common to find used in smaller communities--just check with your dentist or oral surgeon to see who they use to make dentures!!

Good luck!!

I use a lab vacuum oven to cure CJ, but when curing i clamp the door mostly closed (use a clamp to hold it loose) to allow vapors to escape. I'm thinking (not based on science) is that trying to cure under vacuum might actually draw the resin out of the wood. Seems like one would nearly need to keep the blank(s) submerged and cure the whole container if using vacuum while curing. While i still get some push-out of juice with the lab oven, it's a much smaller amount...kitchen toaster oven chambers can continue their heat rise after the heating element shuts down. Can (and did) cause a fire with your wood, fortunately my detached garage did not burn with the buckeye burl.

I do use my vacuum oven when drying to prepare for putting it in CJ. I pull the vacuum and then turn the heat on, but isolate from the vac pump before hitting 70 F so i don't draw moisture into the pump. With the brick mass, it takes the lab oven a while to heat up, but is very stable once heated. Infinitely safer than the fire risk that a toaster oven poses. In my experience, a dental lab oven (no vacuum) would have been just as good, but the old vac oven came up on the auction site for $50 and was only 15 miles away (shipping would be in the $75-$100 range from a private seller today). Another potential advantage to a dental lab oven is that they are much more common to find used in smaller communities--just check with your dentist or oral surgeon to see who they use to make dentures!!

Good luck!!
 

JMC503

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Greenacres, the more I read the more excited I am about this! I tested mine today under vacuum to less than 1”hg and shut the valve. I only lost a few mtorrs in an hour. Also recalibrated my oven to within less than 1/2 of a degree Fahrenheit, so I’m feeling pretty good about this. Thanks for your input.
 

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Hello! I’m wondering if anybody has used a laboratory vacuum oven for stabilizing? I have one, but every time I search the web with this specific question I get no results. I have a VWR 1430M. I am brand new to this stabilizing game. Just bought my first cactus juice. Any tips or tricks or experiences with using a vacuum oven for this application would be greatly appreciated. Clearly I will pull vacuum first with no heat to saturate the wood, but once saturated and removed from the cactus juice bath, can I also cure it under vacuum pressure, so as to retain as much saturation as possible? The boiling point of liquids is reduced greatly in a vacuum, so my concern is to not overcook the resin or create an unsafe situation. Somebody has to have done this before! Thank you in advance.
I use an electric smoker. it works very well.
 
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