Poliester resin impregnation in not so soft woods - Tutorial

[ArielSalaverria]

I've already posted a tutorial on "A very efficient low tech way to impregnate wood and other porous materials" in the past.
Here's a link of it in my website: http://www.aescustomknives.com.ar/docs/tutorial11.htm

This one is based on that one, but with an extra step, to make sure woods and other harder (but not hard enough to use them in natural) materials can be easily impregnated too.

For the particle board piece I've used for the pictures the previous method would have been more than enough, but I also wanted to show that when you put certain techniques in the equation, you can use materials that otherwise are absolutely no good for knifemaking (Can you imagine a particle board handle for instance? How long would that last and feel?) At the end of the pictorial there's a piece of Haya wood that I've also impregnated using this method.

Now with the process!


This is the vacuum chamber I've made for this process. It's a 4" diameter iron tube with the back end closed with a welded flat and the front end threaded to accept the cap you see on the pictures.

It has two different connections, the "V" marked one is the one connected to the vacuum pump. The glass in the middle acts as "trap" in case resin gets sucked in. This way, if you use too much, it gets trapped in the glass instead of messing up the compressor. The connected vacuum gauge will measure the pressure in the vacuum chamber when the compressor is running.

Connection marked with a "P" is for the compressed air I'll use later.

Here's a particle board piece that has already been drilled (5/16" diameter, 3" deep) and threaded to accept the vacuum tube. It weights 1.62 ounces.

Connected to the vacuum tube via the threaded tip.

I then put the block of wood inside a plastic bag with 50 grams or poliester resin (with 10% added styrene monomer to make it liquid enough) and seal the bag with tape.

Note the difference as soon as I start the vacuum compressor.

Once I have that set up, I place it inside the chamber and close it using the threaded cap. The vacuum gauge now meassures 18 linear inches.

 

[ArielSalaverria]

After about 1-2 minutes, I close the vacuum connection, remove the tube for easy manipulation of the rest of the stuff.

Now this is the second step that makes a difference. When I open the intake for compressed air and apply 5 ATMs (70 lbs per square inch) for about 4-5 minutes, this forces an even deeper resin penetration before it gets dried up (about 6 minutes for the resin I use)

Once the resin gets hardened, I stop the compressor and open the cap to retrieve the piece.

Particle wood out of the bag, already impregnated.

Difference between the original weight and the after-impregnation weight: 1.13 oz

Comparo between a regular piece of particle board (left) and a impregnated and polished one (right)

 

[ArielSalaverria]

Particle board, grainy, super soft wood, after impregnation.

Haya good, semi soft wood, after impregnation.

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Thanks for looking!


Ariel

 

[Nathan the Machinist]

Good stuff here. I almost didn't see this thread. I need to try this.

 

[Nathan the Machinist]

As I think about it, there is a safety issue here I wonder if people should be aware of.

Fiberglass resin contains solvents that when mixed with air and compressed can explode, possibly making this a pipe bomb. Enclosed in a plastic bag like this, there should be no fuel/air mixture. But if something wasn't working right and there was a significant amount of solvent fumes mixed with air I think it is possible for this to end in a "boom". Might want to pressurize it outside and at a safe distance.

I am going to try this one of these days. Thanks for posting your idea Ariel. And happy 43rd birthday.

 

[Dan Gray]

As I think about it, there is a safety issue here I wonder if people should be aware of.

Fiberglass resin contains solvents that when mixed with air and compressed can explode, possibly making this a pipe bomb. Enclosed in a plastic bag like this, there should be no fuel/air mixture. But if something wasn't working right and there was a significant amount of solvent fumes mixed with air I think it is possible for this to end in a "boom". Might want to pressurize it outside and at a safe distance.

I am going to try this one of these days. Thanks for posting your idea Ariel. And happy 43rd birthday.

I'm thinking if at 70 PSI as he mentioned you won't have a problem
but at 175 would be a problem maybe? , just thinking about a engine trying to make it fire under compression at 70 pounds you'd be hard pressed to make it do so
at about 100-110 you get better benefit of compression for firing but still you need spark..
a desel with no out side ignition takes much more compression to fire fuel
then again also you need about 12:1 O2/air to fuel mix also for a good big boom..
just my two cents worth

 

[ArielSalaverria]

Nathan,

Thanks for the wishes!

The resin I use has very few fumes and I always use a double plastic bag to ensure there's no resin leakage. I'm used to work with pressure systems as that was my main job working on the locomotives back then and I've been using this for about 6 months now (I always test extensively before postign about a method )

That said, if anyone doesn't feel comfortable with it or have some doubts, please research more before you try it and make sure you're comfortable doing it. As I always say, I just post what works for me, I don't intend this threads to be a how-to step-by-step instructive, just trying to give people some pointers on stuff I made.


Ariel

 

[Will Leavitt]

Ariel,
Are you putting a release agent on the threaded vacuum insert? What are you using for a resin and where do you get it? I've heard Nelsonite is almost impossible to get nowadays.

Neat tutorial and I'll have to make one of these up. I've got some awesomely spalted wood that needs stabilization.

 

[Nathan the Machinist]

I'm thinking if at 70 PSI as he mentioned you won't have a problem
but at 175 would be a problem maybe? , just thinking about a engine trying to make it fire under compression at 70 pounds you'd be hard pressed to make it do so
at about 100-110 you get better benefit of compression for firing but still you need spark..
a desel with no out side ignition takes much more compression to fire fuel
then again also you need about 12:1 O2/air to fuel mix also for a good big boom..
just my two cents worth

Hey Dan,

Yeah I know. But someone recently posted they had detonation just using shop air to blow out oil lines on a piece of machinery. I figure that if machine oil fumes can detonate with shop air, it might be possible that solvent fumes could too.

Ariel is using a different resin than I have used. The stuff I used was flammable and the fumes could just about knock you over. Compressing that stuff in the presence of oxygen might not be a great idea without taking some precautions.

Again, that is a good tutorial. I'm going to try it on some spalted wood a buddy gave me. But I will do it outside and at a distance considering the resin I have.

 

[Dan Gray]

Hey Dan,

Yeah I know. But someone recently posted they had detonation just using shop air to blow out oil lines on a piece of machinery. I figure that if machine oil fumes can detonate with shop air, it might be possible that solvent fumes could too.
.

I can see that happening Nathan with even lower pressures,

if you put an air nozzle ( non safety ) tight against your hand even at lower pressures and touch it off letting just a little escape, it will get real hot real fast.. though I would not advise doing that for safety reasons,
the air in that guys situation atomized the oil adding O2 with it, at some point out the end of the tube mixed at the right ignition point, the heat for the combustion temperature was from the air escaping as in my example,
air friction caused the heat for the combustion.

that's the reason that it's a no no to use oil or grease around the fittings of an oxygen tank..
fuel ( the oil ) , pressure ( the heat source for ignition ) and O2 is the remaining part of the fire triangle..
the way I see it in this set up if there is a fire hazard it would be while letting the pressure of from the pipe but the fire would be on the out side no boom though un less that was contained and ignited.

don't get me wrong there's nothing wrong with using caution and being safe...

it's what's not know that hurt the worse..

 

[SteelSlaver]

Combustion can occur at different levels of pressure and heat with different chemicals. Interestingly some combining occurs at even low heats and pressures. When you open a vessel with a hydro carbon vapor and monitor it with a meter you will begin to get CO readings as the O2 in the air reacts with the hydro carbons at a low level. Like water doesn't boil till 212 but, it still give off vapor. (evaporation). I would be careful taking volatile to higher pressures with an O2 containing air. N2 and Co2 and other inert gasses are readily avalible. Ariel's is working fine and probably continue to. But, another product may not. I will ask a chemical engineer his opinion on Monday if I can remember that long LOL. I do like the method.

 

[ArielSalaverria]

Will,

Good question about the release agent, made me realize a mistake on the translation. I'll correct that in a few.

In about 6 minutes, the resin gets gellyfied, so the process ends there, as its not liquid anymore, there's no more penetration on the wood. Then depending on the composition of the resin, you have another 4-10 minutes for it to dry up. In that time you can just retrieve the vacuum insert with no problems.

I don't use a release agent because of this.

At this 10-15 minutes, the resin it's somewhat hard, but it's best to wait 24 hours before polishing it, as it wouldn't look as good if done before, and would somewhat mess up the polishing stuff.

If you forget to retrieve the vacuum insert and leave it there, it happened to me the past, there's no way you are getting it out, period.


The resin I use it's more liquid than the one I used to use for making micarta in the past (nowadays I use this exclusively). It comes this way from the factory directly, with the maximum added styrene monomer already there. It's more expensive than the other, but in this quantities it's crystal clear, and doesn't leave a blueish tone that would run the natural color of the wood or stag. I only have to add 1% of catalyst (hardener agent)

As for brands, I have no idea, they're different kinds of nautic resin that I buy directly from the distributor in bulk, in unmarked containers.


As for the pressure issue, if anyone doesn't feel comfortable with it and think it's dangerous, please don't try it


Regards,

Ariel

 

[SteelSlaver]

I would think 70# is below the point of detonation for most stuff. I work at an oil refinery and am going to try to remember ( I will just have to remember when I see one) run this by a chemical engineer. Main reason is this is the second time the use compressed air and volatile vapor has came up in a short time. It is done all the time in paint pots etc. I am curious as to what the limits are and what to avoid. The people here tend to experiment which I see as great. I would just hate to see someone get a nasty surprise. Pressure vessel explosions are very very evil.

 

[ArielSalaverria]

Today I was fooling around in the shop after finishing some knives (pics next week) and decided to show the hardness of the impregnated wood in a non conventional way

So I've picked a Gamo CO2 V3 (425fps) pistol and shot round .177" copper pellets to several woods at 3 meters (10 ft)

Depth of the mark made in the impregnated particle board: 0.0141"

Depth of the mark made in a regular particle board: 0.0633"

Depth of the mark made in the impregnated particle board (on a lateral): 0.0389"

Depth of the hole made in a regular particle board (on a lateral): 0.1925"

Depth of the mark made in a regular piece of Guayacan (a hard wood): 0.0338"

Depth of the hole made in my own made micarta: 0.0114"

Close up of the mark in the micarta.

Pellet incrustated on white spruce wood, a soft wood (shot also at 3 meters - 10 ft)

How all the marks/holes were measured.

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Thanks for looking!


Ariel