Scumble is a translucent water-based effect medium. Scumble was developed to be worked and manipulated into the surface. Due to the performance properties and application method, occasionally (depending on the formula of the basecoat of paint) Scumble can re-wet and re-open painted layers readily with the reintroduction of moisture leading to muddy and inconsistent glaze applications. For best results, if painting before application, make sure the basecoat of paint is completely dry before the application of Scumble. If you’re nervous about the paint re-opening, seal the painted surface with Artisan Enhancements™ Clear Topcoat prior to the Scumble application. We always recommend doing a test piece of your Scumble glaze to see how the basecoat and tinted glazes respond.