Epoxy problem

[Goodwin Heil]

I have tried epoxy twice now. Once as a fill for two relatively small knotholes, about quarter sized and once as fill and adhesive for metal weights in a recess and to fill the sides of the recess. Both times it was beautiful when first poured, but when it harden it had formed many air pockets and was all white with them. I have no idea what I am doing incorrectly. Would any of the great minds here be able to direct me in the proper methods.

And If this is not the right place for this query, I apologize. If you tell me where it belongs, I will post it there.

[Steve Eure]

When using epoxy, it is necessary to remove as much of the air bubbles as possible before it cures. Usually if not using a pressure pot for large objects, you can take a propane torch or heat gun to apply heat to the area to disperse the bubbles. Be careful not to get too close or you can burn your project. Take light passes and your problem will be solved.
Check out some youtube videos and you can get much information on this.

[Jim Becker]

For these smaller fills, you need to be very careful when you mix that you don't introduce a whole lot of air and then, as Steve mentions, use a heat gun or torch to encourage any bubbles to leave early in the cure process. Folks who do big pours with resin also have to pay attention to this.

[Goodwin Heil]

Thank you. I will try a heat gun with the next application. I also will "study" you tube further. I really think there is something here if I can just get on to doing it right.

[andy bessette]

Epoxy filler is not the proper repair for a knothole. Use a plug of the same wood.

Bubbles are introduced into epoxy when you stir/mix too fast.

[Bennett Ostroff]

There are a lot of different factors that determine the bubble situation. For most 5-minute epoxies and other quick setting epoxies, it will be impossible to eliminate bubbles in any pour thicker than ~1/16”. They’re too viscous and set too quickly to allow the bubbles to surface and pop. The slower the setting and the thinner the pour, the fewer bubbles you’ll get.

A blow torch will help remove bubbles from the surface, but it’s a two sided coin as heat will cause the epoxy to cure faster, trapping air bubbles sooner. The absolute best bubble preventing measure is to warm the two epoxy parts before mixing. In front of a heater, in the sun, in hot water, etc. And don’t mix too vigorously.

[John K Jordan]

In the ‘70s I prepared metal samples by potting in epoxy before grinding and polishing for analysis by microscope. Air bubbles couldn’t be tolerated For those, a vacuum chamber pulled out the bubbles before the epoxy hardened but this would be difficult for a large piece. Warming also helped by lowering the viscosity but a caution: a little too much heat can accelerate the curing to the point of thermal runaway which can ruin the epoxy with burnt discoloration and cracking. The larger the volume the more the risk.

For bubble-free fill I would contact an epoxy maker like West or SystemThree and ask since. I do see this advice on the SystemThree web site:
https://support.systemthree.com/hc/en-us/articles/360023812054-How-can-I-Avoid-or-Remove-Bubbles-in-an-Epoxy-Application

JKJ


I have tried epoxy twice now. Once as a fill for two relatively small knotholes, about quarter sized and once as fill and adhesive for metal weights in a recess and to fill the sides of the recess. Both times it was beautiful when first poured, but when it harden it had formed many air pockets and was all white with them. I have no idea what I am doing incorrectly. Would any of the great minds here be able to direct me in the proper methods.

And If this is not the right place for this query, I apologize. If you tell me where it belongs, I will post it there.

[mike stenson]

I have a small crock pot that I use for warming glue (hide and epoxy). Just water, kept warm, and stick the bottles in it. It's easier than using a heat gun when filling cracks, checks, or knots.