Follow up on Embedding in Resin

[Ray Binnicker]

I posted a question earlier on embedding in polyester resin. I was having trouble finding out how to get rid of all the bubbles. Got some encouragement and suggestions from you guys, and I thank you. I was thinking it was my technique, i.e., wrong ratio of hardner to resin, wrong temperature, leaving it set too long, not letting it set long enough. I went through a quart of resin; all with some number of very small bubbles. Well, I solved the problem. I bought a Paint Pressure Tank from Harbor Freight, poured up a bottle stopper, placed the mold w/liguid in the tank, pressurized to 25 lbs and waited 45 mins. Viola, not a single bubble!!!!! Clear as glass!!!! This is a not-so-good picture of what I was trying to do. The bottom half is colored and the top half is clear with (in this case) a US Flag lapel pin embedded.

[John Terefenko]

Nicely done. That is the way most casters do it using a pressure pot. This opens a whole lot of possiblities not only for stoppers but pens as well. Thanks for showing and you did a great job with it.

[Richard Madison]

Cool stopper. Would like to learn the mechanism by which pressurizing the resin helps eliminate the bubbles. What am I missing?

[phil harold]

Cool stopper. Would like to learn the mechanism by which pressurizing the resin helps eliminate the bubbles. What am I missing?
+1 on that

I would have tried a vacuum enviroment first...

[Ray Binnicker]

Richard, Phil,
A friend, after looking at the set-up, asked the same question; "why pressure and not vaccumn? I went with the pressure tank because of something I read. It was a very brief reference in a resin casting tutorial. It seemed simpler to try than the vaccumn. My friend also asked; "where do the bubbles go"? The only answer I have is; "They are in "bubble hell"!!:)
Ray Binnicker

[Darryl Hazen]

The bubbles are still there. They're just compressed to a size you can't see. The vacuum method requires a bell jar and vacuum pump. Pulling a vacuum cause the bubbles to rise to the surface and dissipate. Most of the bubbles are the result of over mixing the epoxy and entraining the air.

[Jim Underwood]

I've read that some guys use a combination of vacuum and pressure....

[David Walser]

I've read that some guys use a combination of vacuum and pressure....

Just not at the same time (I hope)!

[Jim Underwood]

:p Well of course not! ;)

I can't remember which way they did it, whether they vacuumed all the bubbles out, and then compressed the remaining ones with pressure... but there was a certain order.

[Chris Stolicky]

I believe vacuum is used more when someone is casting what they call "worthless wood" - a mix of what is usually a jagged cut off and resin. The vacuum pulls the resin into all of the nuks and crannies (english muffins anyone?)... The pot is then switched to pressure to force the small bubbles out of the resin.

If its only resin casting, pressure is all you really need.