Q: How often should release agent be applied to plywood form panels?
A: Plywood forming panels usually are treated with a form release agent at the mill, but it's still important to evaluate their condition carefully before using them for the first time. Unless the mill treatment is reasonably fresh, the panels may need another treatment of release agent before the first use. Even medium-density overlays should be treated with a chemical release agent before the first use and between each pour. Applying a thin film of form release agent to both reused panels and new panels that are not freshly mill-treated will prolong the panel's life, enhance its release characteristics, and minimize the potential for staining the concrete. Apply the release agent a few days before using the forms for best results.
You also should determine whether an edge sealer was applied at the mill, and if not, seal any cut edges with two coats of polyurethane paint or varnish before the first pour. Otherwise, the forming panels will absorb moisture and swell at the edges.