If you plan to color-fill, how can you tell if you’re sandcarving deep enough for a “pool”?

1. Look for a dark shadow around the outline of the letter or image. This is a good indication and easily seen in white light.
2. Use your fingernail and rub up to the edge of the blasted area. If your fingernail stops without affecting the mask, it is deep enough. If you affect the mask by tearing it or pushing it, your blast is not deep enough. 

Let’s say you do not etch deep enough – you peel the mask off and lose some paint due to the paint being above the glass plane – no problem. You can put a dab of paint in the area, let it dry, then scrape off the excess with a sharp razor blade. 

-Darin Jones, IKONICS Imaging