For some reson when I remove the casting from the mold the surface has millions of tiny holes in it. Are these air bubbles? What I dont understand is that the first 5-6 castings are fine and I am doing it the same way still. It si hapening on more than one mold too. Any help you can give me would be great.

Hi Matrix

Air bubbles are a real problem with resin casting. That's why commercial casters use a vacuum chamber to force the bubbles out.

If you're casting stuff at home, try (as far as possible) to make sure there are no bubbles in the resin before you pour it. Dusting the mould with talcum powder before you use it is often a good idea, because it draws the resin into awkward nooks and crannies. :-)

Hope this helps

Rowan

If you are using the same batch of resin over and over for multiple castings, it could be that your resin is begining to cure, thus becoming thicker and having more surface tension. This could be causing the bubbles. Also, as the resin gets old, more than a few months, it looses its shelf life and doesn't set-up and mix as well. Lastly, if you paint the resin on the mold first, you should have less air bubbles on the surface.

Make sure that you let the release agent dry and make sure that you don't use too much release agent. If the mold is fairly wet you will get the pin holes or little cavities in the casting.