- 1). Choose a spot on the outside of the mold to use as a testing area. This spot should not touch the inside of the mold itself in case the release doesn't go well; the back of the mold is usually a good spot.
- 2). Cut a few grooves into the plastic using the craft knife to test the effectiveness of the release agent in cramped and textured areas. If the plastic is thick, cut some small holes. If the plastic is thin, make light scratches so as to avoid cutting through to the inside of the mold.
- 3). Coat the testing area generously with the release agent. Just as you'll make sure to work the agent into the crevices and tights spots on your mold, work it into the scratches and grooves you've cut into the test patch.
- 4). Spread a little molding compound on the test area. Lay the mold flat on a table, test patch up, so that you can spread the molding compound at least a quarter of an inch thick.
- 5). Let the compound set and harden.
- 6). Separate the molding compound from the test patch with your fingers. Observe whether any of the compound sticks to the mold and how cleanly it comes away. Ideally, your release agent should help the compound to pull away without any sticking or misshaping.
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