Getting rid of bubbles in my finished casting

Katie,

While you may not have seen the bubbles after you poured your resin, they were there while it is curing.  Unless you’re creating extreme heat to sand your pieces (an industrial belt sander or something similar), they were there all along.

I have also had this happen with some of my castings.  I don’t know the exact physics of this, but there is enough surface tension (or something like it) to get the bubbles to cling to the edge of your casting rather than rising to the top.  (see how all your bubbles are along the edge?)

The best way to fix this in the future is to make sure you mix your resin in such a way as to get as few as bubbles as possible in your casting. 

Since your resin is colored, it may be difficult to see the bubbles.  I like to use a very bright LED nightlight to shine like a spotlight over my castings after I have poured.  It has helped me a lot to find bubbles that I didn’t see before. 

As for saving the project you have here, you have two options:

1.  Continue to sand until all the bubbles are gone.
2.  Try to repour resin into the holes the bubbles have created.  This way is a bit more tricky as it is almost impossible (for me anyway) to recreate the same color in resin from one batch to the next.  Your project appears to be dark, so just dabbing in a bit of clear may work just fine for you.