Mold & Casting Questions

First of all, use heat to help the resin in those small amounts cure faster. Even consider preheating your mold so they are nice and warm or place the mold with resin inside in a warm place to cure. This will help with any tackiness.

Flat surface. What I like to do is mold release a piece of glass, then over pour the mold until their is a puddle on top, then starting from one side, lay the glass onto the top of the mold pushing the excess resin off onto your work area (I'd recommend a layer or two of aluminum foil), then allow to cure. If needed put a weight on the top of the mold and allow to cure. When it has cured, remove the glass and demold. You will have perfectly flat back pieces. If any, you may have a tiny tiny layer of flash to remove with your finger nails or an Excel Knife.

The other way is to over pour and quickly squeegee off with a popsicle stick if you haven't already tried this. I'd honestly try this first to see if it gives you adequate results because it is so much quicker.

Mike