Air Bubbles In Epoxy

[11bravo]

Was looking at some epoxy the other night in the cup as I stirred it and noticed that when the two parts were put into the cup they were nice and clear.
As I stirred, they became cloudy; I assume from the air bubbles introduced.
When I then looked at a fillet and really looked at it, it was full of voids from air bubbles.
Surely those voids contribute to weaker fillets.
Got me to thinking,

Would there be any advantage to putting the mixed epoxy into a vacuum chamber to draw the bubbles out/up before pouring into place as fillets?

I'm not talking anything too scientifically fancy.
As I use a Rival Seal·A·Meal for vaccing purposes, was thinking that if I had one of these - vac canister - I could just use it.

Could be some downsides:

1. Need more epoxy for the same size fillet.
2. Heavier.
3. Harder to sand.[/list=1]
   
   Thoughts?
   
   Greg

 

[strudleman]

I usually put a filler in my epoxy when making fillets. Colloidal Silica (West System 406). If you turn your epoxy into a peanut buttery consistency, your air bubbles are gone. And as a nice side benefit, epoxy at that consistency doesn't run a bit, so you can spin your rocket around and do all of your fillets at once!

I paid $7 for the can and I still have about half a can left after months of building. Also, I've used it with Aeropoxy and several of the cheaper brands and it's been compatible every time.

 

[nichanderson]

Yes. I do it all the time, especially when you want a nice finish. It is especially useful during pressed plate layups, vacuum or not. Much better surface finish texture than without.

I simply took the lid from a jar of pasta sauce, drilled a hole, threaded in thread->barb adapter and that was it. Pull a vacuum and watch the bubbles coming out of the epoxy. Watch for foaming, which can occur depending on the viscosity of the epoxy.

I would not recommend doing with it with anything that is designed or could be used for food service.

Nick Anderson

 

[jraice]

Fillers... I plan on using them for the first time. I have some milled fiber that I plan on using for external fin fillets. I have regular 2 hour hobby grade epoxy and I have some 10 hour laminating resin. What would work best?