Can you stabilize blanks without vacuum? Test results!

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MesquiteMan

MesquiteMan

Retired Head Moderator
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I recently decided to do some testing to see what kind of stabilizing results one could obtain without using vacuum. This test was performed with a thermosetting professional stabilizing resin. I started with 30 1" x 1" x 5-1/4" spalted pecan pen blanks that were air dried. I then placed them in my toaster oven at 200° F for 24 hours to make sure they were as dry as possible. I recorded the weight in grams of each blank before and after placing in the toaster oven and amazingly, from air dry to oven dry, they lost an average of 16% weight! Since weight equals water in this instance, and water occupies cellular space that could be occupied by the resin, it is safe to say that it is a really good practice to oven dry your blanks before stabilizing!

After cooling down to room temperature, I sorted them in groups based on weight and then choose 3 blanks from 4 different groups of weight sorted blanks to create 3 sets of 4 blanks with similar weight distributions between each group.

The first set of 4 blanks were placed in a chamber and weighted down. I then added the stabilizing resin to submerge the blanks and set them aside to soak. I allowed them to soak for 24 hours.

The second set of blanks were placed in a chamber, weighted down, and submerged in the stabilizing resin. This chamber was then placed in my pressure pot and pressurized to 70 psi. I allowed these blanks to remain at 70 psi for 24 hours. The pressure was then released and the blanks were allowed to soak for 1 hour with no pressure.

The final set of blanks were placed in a chamber, weighted down, and submerged in the stabilizing resin. This chamber was then connected to a vacuum pump and pulled down to a 99% vacuum until the bubbles stopped coming out of the blanks. The vacuum was then released and the blanks were allowed to soak for 30 minutes.

After their respective cycles, each blank was removed from the chamber/resin and allowed to drain for 30 minutes. After draining, each blank was wrapped in foil and cured in a pre-heated 200° F toaster oven for 2 hours. Once cured, the blanks were unwrapped and allowed to cool. The excess material that had polymerized on the outside of the blank was scrapped off, being careful to not remove any of the wood. All 16 blanks were then weighed and recorded.

The weight results from each blank were then input into an Excel spreadsheet and the differences and % were calculated as well as an average for each set of blanks. The results are shown on the graphs below.

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This is the average weight gain from raw to finished blank as a % for each group
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One thing that I found very interesting is what happened to the blanks that were placed under pressure. After removing from the pressure and allowing to soak, they continued to bubble for an hour. To me, this proves the principle that pressure may indeed push the resin into the blank by compressing the air inside the blank but once the pressure is removed, the air inside the blank expands and pushes some of the resin back out of the blank. The pressure treated blanks also had the highest amount of cured resin on the outside of the blanks by far which shows that the pressure continued to push the resin out while curing.

These pics are NOT under vacuum!

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When curing all blanks, some of the resin is going to leak out and polymerize on the outside. For this test, I also recorded the weight right before curing as well as after. The soaked and pressurized blanks lost a significant higher % of their weight after curing. To me, this shows that with vacuum, the atmospheric pressure is keeping more of the resin in the blank.

Here is a chart with the average % weight loss for each group between their respective cycle and cured.

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So, based on this testing, I would have to say that yes, you can stabilize blanks by just soaking or with pressure but will get a higher concentration of resin inside the blank, and thus a better stabilized blank if you use vacuum.

Note: This test was done using ordinary shop type equipment. Most of us to not have access to super high pressure as used by some professional stabilizing companies so I am not saying that pressure is not effective, just that, based on this test, for the home shop environment, 70psi is not as effective as a deep vacuum.
 

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Interesting results but not surprising, I have wondered about the big deal that pressurized is made out on the forums sometimes. When pulling a vacuum to remove air from what ever items in a liquid can be accomplished with a hand vacuum pump and a good seal.

I worked for a company that repaired the transformers on the poles. When we filled them with the oil we would pull a vacuum on them till the bubbles stopped foaming on the surface.

I had asked the owner of the company why he used vacuum in stead of a pressurized system. He sort of smiled and said that it was easier and you get better flow of the oil into the winding by pulling the air instead of blowing or compressing air into the oil. As you will all ways get some air entrapment into the liquid you are pressurizing.

Great post, thanks
:clown:
 
PTsideshow said:
Interesting results but not surprising, I have wondered about the big deal that pressurized is made out on the forums sometimes.
Click to expand...

Just to be clear...I still HIGHLY recommend pressure for casting when embedding anything in the resin. This is because the casting resin will polymerize while under pressure while the stabilizing resin will not. If you have a pocket of air in a blank and pull a vacuum, the pocket will grow until it spills out but the pocket will still be full of air. With pressure, you can crush that air into oblivion and get rid of it!
 
24 hours? I soak for a week or more and it seems to make a big difference!

Going to have to look into a home vacume system, I want the best results I can get in my shop...
 
Thank you Curtis. Your research is always well thought out and documented. Your then sharing it with the rest of us is greatly appreciated. I just wish that all manufactures were equally honest.
Charles
 
I understand it's not under vacume in the pic but is that the chamber you use? I see some have used pickle jars but I need more space than that. Thanks
 
I would like to add to the Experiment Curtis did and say that High Pressure will get better results than the vacuum. When I say High pressure it would be 3000 to 5000 PSI. Now this is not what the average person would have in there shop and therefor just take it as an side note. I also mix resins that is a lot more like syrup and will not work in a vacuum at all. I found a way to use Silmar 41 resin and heat cure it rather than curing with MEKP, it has a lot more weight than normal stabilizing resins.
I have found that if you dry the wood in an oven and get the moisture below 5% when it is hot that it is best to put in the solution then and not to let it cool down first. The moisture content will go back up at 10% - 11% very quickly. (In Georgia)

Great analysis Curtis
 
Thanks for taking the time to perform these tests and for sharing your results. Your efforts are an inspiration to many of us pen turners!

Tom
 
thank you so much for taking the time to make the test, and for presenting it so beautifully!

I wonder one thing:
although it's obvious that vacuum is better that plain soak, is soaking good enough? in other words, if the purpose of stabilizing is preventing a punky blank from blowing on the lathe, or making a blank a bit sturdier (and not just adding weight) that perhaps 95% weight increase might suggest that the blank is "pretty stable".
or maybe, the significant difference between soaking and vacuuming might indicate that soaking simply is uneven, unreliable or doesn't penetrate past a certain depth.

what's your opinion?
 
I took one each of the sets of blanks I did and cut them in half length wise. I used dyed resin for my testing so I could do some "post mortem" analysis. The soak and pressure blanks had penetration to the center of the blank but there were some areas that were still natural color and un-dyed. The vacuum stabilized blank had complete, uniform color. I then looked at each blank under blacklight (the resin I used has fluorescent markers in it for this purpose) The pressure and soak blanks had spots that did not fluoresce at all while the vac blank was uniform.

Now, all that said, I do think you could get descent results by just soaking. It will not be ideal, but it should work if the budget is just not there to invest in a vacuum system.

studioso said:
thank you so much for taking the time to make the test, and for presenting it so beautifully!

I wonder one thing:
although it's obvious that vacuum is better that plain soak, is soaking good enough? in other words, if the purpose of stabilizing is preventing a punky blank from blowing on the lathe, or making a blank a bit sturdier (and not just adding weight) that perhaps 95% weight increase might suggest that the blank is "pretty stable".
or maybe, the significant difference between soaking and vacuuming might indicate that soaking simply is uneven, unreliable or doesn't penetrate past a certain depth.

what's your opinion?
Click to expand...
 
MesquiteMan said:
I took one each of the sets of blanks I did and cut them in half length wise. I used dyed resin for my testing so I could do some "post mortem" analysis. The soak and pressure blanks had penetration to the center of the blank but there were some areas that were still natural color and un-dyed. The vacuum stabilized blank had complete, uniform color. I then looked at each blank under blacklight (the resin I used has fluorescent markers in it for this purpose) The pressure and soak blanks had spots that did not fluoresce at all while the vac blank was uniform.

Now, all that said, I do think you could get descent results by just soaking. It will not be ideal, but it should work if the budget is just not there to invest in a vacuum system.

studioso said:
thank you so much for taking the time to make the test, and for presenting it so beautifully!

I wonder one thing:
although it's obvious that vacuum is better that plain soak, is soaking good enough? in other words, if the purpose of stabilizing is preventing a punky blank from blowing on the lathe, or making a blank a bit sturdier (and not just adding weight) that perhaps 95% weight increase might suggest that the blank is "pretty stable".
or maybe, the significant difference between soaking and vacuuming might indicate that soaking simply is uneven, unreliable or doesn't penetrate past a certain depth.

what's your opinion?
Click to expand...
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must... buy... new... toy...
 
studioso said:
must... buy... new... toy...
Click to expand...

Just to be perfectly clear to all here...it was not my intention to post this to try to create some sales. I did the test and thought everyone here would find it useful, regardless of what type of resin you use. I honestly had no ulterior motive on posting this.
 
Curtis,

Question. Did the soak and pressure blanks have uniform penetration to any consistent depth, or was it spotty thoughout?

If folks can expect consistent penetration to say 1/4" by soaking, then it seems reasonable in most cases they can pre-cut their blanks to a thickness that accounts for the 1/4" penetration and the diameter of the tube. Right?

Thanks,

Tom
 
MesquiteMan said:
I took one each of the sets of blanks I did and cut them in half length wise. I used dyed resin for my testing so I could do some "post mortem" analysis. The soak and pressure blanks had penetration to the center of the blank but there were some areas that were still natural color and un-dyed. The vacuum stabilized blank had complete, uniform color. I then looked at each blank under blacklight (the resin I used has fluorescent markers in it for this purpose) The pressure and soak blanks had spots that did not fluoresce at all while the vac blank was uniform.

Now, all that said, I do think you could get descent results by just soaking. It will not be ideal, but it should work if the budget is just not there to invest in a vacuum system.
Really an impressive, well documented experiment.

For the amount of stabilizing I do, can't justify the price of a vacuum setup, so I've soaked the occassional blank. I've found they need a lot more than a day -- sometimes it is two or three days before they are sufficiently saturated to stay sunk when the weight is removed. It is amazing how cool it is to turn a stabilized blank, that was previously punky.

Thanks
Steve
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I decided to shoot some quick pictures of my test blanks that I ripped in half. These were shot with my iPhone so the lighting and color balance is off a little but should be good enough to show the results.

All three blanks ripped lengthwise with the insides facing up.
From left to right: Vacuum, soak, pressure

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Close up of the Vac Blank
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Closeup of the soak blank:
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Close up of the pressure blank:
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Each blank set was dyed a different color so I would not get them confused once polymerized. In the soak and pressure close-ups above, you can see the areas that a lacking color, thus lacking stabilizing resin. The resin did penetrate all the way through the blank, though.

Here is a photo taken with a blacklight. The blanks are in the same order left to right: vac, soak, pressure. The photo was hard to get and does not show the contrast like it did in real life but you should be able to see a more intense glow on the vac blanks.

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The stabilizing resin isn't a 2 part curing resin like the casting resin?

I have a pressure pot from harbor freight. With the information I have read and seen I think that the pot is sufficient for pressure casting like coffee beans, cactus, banksia pod, etc. Am I right?
 
Donovan's Corner said:
The stabilizing resin isn't a 2 part curing resin like the casting resin?

I have a pressure pot from harbor freight. With the information I have read and seen I think that the pot is sufficient for pressure casting like coffee beans, cactus, banksia pod, etc. Am I right?
Click to expand...

Depends on what you are trying to use. The resin in this experiment is a professional stabilizing resin similar to what the stabilizing services use. It is NOT a 2 part resin and does not cure by chemical reaction. It cures by heat alone.

And yes, you are correct that a pressure pot it used for pressure casting things like coffee beans, etc. The HF pot is not on my list of recommended items due to a failure I had but many here use it.
 
Curtis,

The pressure pots in your casting videos on your website look a lot like the HF model I have. If they aren't then where are they from. Your failed use was it dangerous or just annoying?

I have been using the HF pressure pot with good success dying my pen blanks. There are some that do not allow the dye to penetrate to the center without the pressure on overnight.

A vacuum system will be next on my purchase list.
 
thanks for your stabilization data!
question: could much of the weight-gain in the 3rd set be from the thin external layer of resin instead of the absorption? you report that some of the resin is picked off after heat-curing but i'm wondering about the outer coating you can't pick off.

also, what happens to resin absorption rate if the wood is not bone-dry? will the resin displace the water?

thanks
w
 
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Donovan's Corner said:
Curtis,

The pressure pots in your casting videos on your website look a lot like the HF model I have. If they aren't then where are they from. Your failed use was it dangerous or just annoying?

I have been using the HF pressure pot with good success dying my pen blanks. There are some that do not allow the dye to penetrate to the center without the pressure on overnight.

A vacuum system will be next on my purchase list.
Click to expand...

My pot blew up and was EXTREMELY dangerous! The pots in the video are Binks pots made in the USA. The HF pot is a knock off of the Binks pot. See this thread for more on my failure: http://www.penturners.org/forum/f43...ot-failure-my-wife-almost-became-widow-51588/
 
winter07@pacbell.net said:
thanks for your stabilization data!
question: could much of the weight-gain in the 3rd set be from the thin external layer of resin instead of the absorption? you report that some of the resin is picked off after heat-curing but i'm wondering about the outer coating you can't pick off.

also, what happens to resin absorption rate if the wood is not bone-dry? will the resin displace the water?

thanks
w
Click to expand...

Each blank in the testing was scraped with a carbide scraper to remove the resin on the outside of the blank after it was cured. All 12 blanks were scraped down to the wood with no resin left on the outside before weighing the final time.

The drier the wood, the more resin you can get into the wood. No, the resin is not going to displace the water in the wood so any water that is already in there will still be in there. Some of it will boil off under vacuum, though.
 
What does the 99 percent vacuum equal in terms of PSI? I have a carbon vane pump that will pull about 18 to 20 PSI vacuum for graphic arts work, would this be in any way useful for this procedure?
 
Gary Beasley said:
What does the 99 percent vacuum equal in terms of PSI? I have a carbon vane pump that will pull about 18 to 20 PSI vacuum for graphic arts work, would this be in any way useful for this procedure?
Click to expand...

Gary,

I have never seen vacuum measured in psi. To my knowledge, there is no gauge that reads in psi so most likely you are achieving 18-20 "Hg (inches of mercury) which is the most common measurement of vacuum, at least in the US. Since vacuum depends on your elevation above sea level, 18-20" Hg in one area is a weak vacuum while in another, it may be close to full vacuum. That is why I state vacuum in % vacuum rather than a number.

The maximum theoretical vacuum is 29.92" Hg at sea level on a standard atmospheric day. For every 1,000' above sea level you are, you loose 1" of maximum vacuum. This is because the higher you go, the thinner the air is. The way to convert to % vacuum is to take the reading on your gauge and divide it by the pressure for your given area. In my case, I am a little less than 1,000 above sea level. That means my maximum theoretical vacuum is around 28.92 (29.92 - 1). If I then take the reading on my gauge, which for me is 28.8 or so, and divide it by 28.92, I get 99.5% vacuum.

Remember the definition of a perfect vacuum is the absence of all molecules. At a 99.5% vacuum, I am removing 99.5% of the air and gas molecules from my chamber. Granted, cheap gauges are not real accurate at high vacuum so I doubt I am getting that much but I am way up there.

According to wikipedia, your city is 1,180' above sea level. That means your maximum theoretical vacuum is around the same as mine at 28.92 or so, actually a little less so let's use 28.9". If you are only getting 20" Hg of vacuum, you are only generating 69.2% vacuum (20/28.9). This means in the best case scenario, the most amount of air you can possibly remove from the blank is 69%. As long as there is air in the blank, it is taking up space that the resin could be occupying.

You should be able to get fair results but not the best possible.

Sorry for the long reply! Just thought I would try to explain how it all works a little for you!
 
MesquiteMan said:
Donovan's Corner said:
Curtis,

The pressure pots in your casting videos on your website look a lot like the HF model I have. If they aren't then where are they from. Your failed use was it dangerous or just annoying?

I have been using the HF pressure pot with good success dying my pen blanks. There are some that do not allow the dye to penetrate to the center without the pressure on overnight.

A vacuum system will be next on my purchase list.
Click to expand...

My pot blew up and was EXTREMELY dangerous! The pots in the video are Binks pots made in the USA. The HF pot is a knock off of the Binks pot. See this thread for more on my failure: http://www.penturners.org/forum/f43...ot-failure-my-wife-almost-became-widow-51588/
Click to expand...

Well my shop will be on a budget for a little while. In the mean time the pressure pot will sit in the nook outside my shop and the latches will be held together with a tow chain and a strong nylon cord and pulley attached to the pressure relief valve.
 
MesquiteMan said:
Gary Beasley said:
What does the 99 percent vacuum equal in terms of PSI? I have a carbon vane pump that will pull about 18 to 20 PSI vacuum for graphic arts work, would this be in any way useful for this procedure?
Click to expand...

I have never seen vacuum measured in psi. To my knowledge, there is no gauge that reads in psi so most likely you are achieving 18-20 "Hg (inches of mercury) which is the most common measurement of vacuum, at least in the US. Since vacuum depends on your elevation above sea level, 18-20" Hg in one area is a weak vacuum while in another, it may be close to full vacuum. That is why I state vacuum in % vacuum rather than a number.
Click to expand...

Actually psi works for positive or negative pressure, it's just the force applied per square inch by the difference in atmospheric pressure versus the containers pressure. Though in the case of the equipment I have you may be right about it's terms. The scale is merely numbered and everyone working with it I've known refers to it as pounds of pressure.
Does it make any difference when stabilizing if you cycle the vacuum up and down to allow the fluids to "pump" thier way in? Like an hour on then a rest time then another hour etc.
Either way I would assume when doing blanks it would maximise your efforts to predrill the blanks with a minimum size hole so the stabilizing agent can work it's way in from the inside too. That would probably be recommended for the unpressured soak method at any rate.
 
Gary, you are correct that vacuum COULD be measured in psi but it would be a number lower than 14.7 since atmospheric pressure at sea level is 14.7 psi. A 28.92" Hg vacuum at sea level is .49 psi. That is if the gauge is measuring the amount of vacuum. However, if you are using it in an application where you are measuring the amount of force the outside of the container is applying to the inside, then sure, it would be higher than 14.7 psi. However, the typical rotary vane vacuum pump that a hobbyist might use in the US is typically rated in the amount of vacuum they will produce in either Inches of Mercury or microns.

I have found minimal value in on and off. Then again, I am able to achieve a really deep vacuum with my pump. Same with pre-drilling the blanks. I have been able to get 100% penetration in a 7.25" x 7.25" x 3.5" piece of spalted hackberry that was not punky. I dyed the resin burgundy and once cured, I turned a bowl out of the blank and it was 100% uniform color throughout the blank. For just soaking, I would also think pre-drilling would be helpful.
 
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Thanks for posting all this stuff Curtis it really helps some of us new to stabilizing guys get started. This was some of the best information I have found so far.
 
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