What should be placed between a plywood patch and the pressure plate to prevent sticking if glue is extruded?

To prevent sticking between a plywood patch and the pressure plate when glue is extruded, using a piece of waxed paper or vinyl plastic is highly effective. Waxed paper has a smooth, non-stick surface that can easily release from the glue if it oozes out during the curing process. This allows for a clean separation without damaging the patch or the pressure plate.

Vinyl plastic serves a similar purpose by providing a barrier that helps to keep the pressure plate from adhering to the plywood patch. Both materials effectively prevent any residual glue from bonding to the surfaces, facilitating easier removal once the adhesive has set.

While other materials like plastic wrap or aluminum foil can provide some form of separation, they may not be as effective at preventing adherence as waxed paper or vinyl plastic. Plastic wrap can sometimes cling due to its adhesive properties, and aluminum foil may not provide a smooth enough surface for clean removal. Using a cloth towel also does not serve the same purpose, as it could absorb moisture from the glue instead of acting as a barrier, which might lead to unintended sticking or residue.