Just mix Top Flite Microballoon Filler with hobby epoxy or aliphatic resin...its micro-sized glass bubbles make your glues go farther and weigh less! Use your Microballoon/epoxy mixture to make fillets, and as an exceptionally lightweight, easily sandable filler for surfacing over imperfections, wood grain and fiberglass cloth. Microballoon Filler also helps epoxy and polyester resins cure without shrinking to a hard, sandable, moisture-resistant finish. The bottle's convenient spout lets you pour easily without waste. It's also compatible with aliphatic resin and acetone-based glue. Each bottle contains 8 fluid ounces.