Also, MOST polyester resins go thermal when they kick off. The larger the batch, the more thermally active they are. I've seen paper cups with too large a batch in them spontaneously combust. Epoxy resins are better IMO, and most (but not all) are more thermally stable than the polyester types, but make sure you weigh your proportions and heed all directions relative to maximum recommended batch size. Slower cures allow more work time to iron out the bubbles and feed any resin starved areas. Bear in mind, strength comes from the fabric, not the resin. Don't be tempted to butter up the outside with a heavy glaze of resin. There are surfacers for making it all pretty and smooth. Focus on good distribution and keeping the fabric tight to the mold and air pocket free.
I like to use 6mil bags. (like freezer bags) I split them down the side seams and tape one side down to the table. Lay the glass on top of this one, drizzle on some resin, then pull the other side over top and press the resin through the glass. You can see through the bag to work the resin into every fiber of the cloth. When it's happy, peel that piece up and lay it on. A bondo spreader works good for ironing the resin into the fabric. Sometimes I cut the whole top side of the bag off the table so I have a hand hold to lay the glass on the mold, but many times it drags the fabric out of place on the mold when trying to peel it back. Try glassing something besides your project first, just to get a feel for working with it. Does not require the practice time of good welding, but experience does help!
