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Working with Epoxy

Started by Brad_bb, August 01, 2013, 02:24:42 AM

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Brad_bb

Well, I used West Epoxy systems (epoxy and fast hardener) for the first time this week.  I used it to fill voids in some White oak, knot holes, checks, etc.  I had also done some glue ups of the walnut boards and had a couple spots that didn't stay together all the way so I filled them with epoxy too.

I assume it's ok to use the Epoxy for these filling issues. As opposed to "table top epoxy"?  I noticed that some air bubbles can get trapped.  Is there a trick to removing them?  Back when I worked for an aircraft company we had some type of clear adhesive/sealant that we mixed up and put in a vacuum chamber to draw all the air bubbles out before taking it out and using it.  Maybe I need to do something similar?  I don't have a vaccuum chamber per say, but I could create one by making a wooden box that I can put into my vaccuum veneer press bag to draw a vacuum?

Lastly, what type of cups do you use to mix the epoxy in? 
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

beenthere

I usually pass some heat over the two part epoxy to get those bubbles to surface and pop.
A few passes with a propane torch works for me. You get the feel for it, and don't stay in one spot.
This is done before the epoxy sets up, naturally.

And lastly, paper - not plastic.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Mooseherder

Ditto to the propane torch method when used for table tops and should work also for what you're doing for spot areas.
I'm sure you know this but make sure you are in a well ventilated or outside area.  It works well.  Just keep moving.  You'll see the air bubbles disappear.

Claybraker

Any heat source should work, heat gun, hair dryer, but the best approach is try and prevent them forming in the first place.

When mixing, try not to lift your tool, use a slow circular motion. If you want to get fancy, they make epoxy mixers for small quantities, often used in rod building. Here's the one I have:
http://www.mudhole.com/Automatic-Epoxy-Finish-Mixer

wildbill

i learned the hard way to use heat to remove bubbles. 

i ended up with very tiny bubbles on a desk i was making for my kid.  my solution was to put another coat of epoxy over the first but during the mixing i added a jar of glitter.  the bubbles blend in well with the glitter.

if you are making something for a 6 year old girl this is an option ;)
Raider Bill's favorite son

Leigh Family Farm

When Iworked on sail boats, we used plastic cups for mixing. Yes the plastic does eventually melt from the epoxy but they were about $2/100 cups. I was forced to only mix small batches because of the size of the cup and the fact that melting plastic hurts!

There are no problems; only solutions we haven't found yet.

hardtailjohn

West System is awesome stuff!!  I'm not a fan of heat to remove bubbles, but ya do what ya gotta do sometimes.  Bubbles should be prevented during mixing and applying. The Gougeon Bros. (who invented West System) have a great book out in PDF all about using their product. It's well worth the read!

http://www.westsystem.com/ss/assets/HowTo-Publications/GougeonBook%20061205.pdf

One thing that I found that really helps when doing stuff like you mention (filling, etc.) is to get the proper additive and the proper catalyst. It sure makes the job easier!
John
I'm so far behind, I think I'm ahead!

Coach

My understanding of epoxy and bubbles. When the temperature rises 'after' you've applied epoxy, you get bubbles.  Warmer tempts means more pressure and therefore less room for oxygen in the wood, so it's migerates out and creates bubbles.

When the temperature drops is the best time to apply epoxy.  In this case, Air gets sucked into the wood, rather than released from it.

So a good idea to avoid applying epoxy in the morning.

beenthere

Coach
Likely the change in temps from cool to warmer is what is releasing the bubbles.


Also, an acetone mist will work.
And as well, just warm breath onto the epoxy will often be enough to get the bubbles to pop at the surface.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Coach

A good practice is to warm up the room the wood is in. Once it's been warmed up a couple of hours, apply the epoxy while letting the area cool down normally.  At least that's what i was taught to do in cedar strip canoe building.  Works great, no bubbles.

Most important is not to increase the temperature once the epoxy has been applied.

Brad_bb

It's been 80-85 in my shop.  My shop is 40'X40' so it would take flaming the heaters on in summer time, plus is warm enough in here already, I don't think I'm going to be making it any warmer, but I appreciate all the inputs.
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

beenthere

Don't warm the shop but just warm the epoxy.  The differential will pop the bubbles, but then maybe you like those bubbles.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Brad_bb

Tried the heat yesterday.  It does help eliminate the bubbles.  Thanks ya'll.
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

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