How long should a scratch coat cure before applying the leveling coat?

A scratch coat is an essential step in the process of preparing a surface for tiling, as it enhances adherence for leveling and finishing layers. The ideal curing time for a scratch coat is typically around 24 hours. This time frame allows sufficient hydration to occur, which is critical for achieving the right consistency and strength of the coat. Proper curing helps to prevent cracking and ensures that the surface is stable enough to support subsequent layers, such as the leveling coat.

If the scratch coat is applied too soon or not allowed to cure sufficiently, it may not bond correctly with the leveling coat, leading to potential delamination or adhesion failures. Allowing a full 24 hours also permits the excess moisture content to dissipate, which is necessary to create an optimal substrate for the leveling layer. By adhering to this standard, tilers can maintain the integrity of the overall installation and ensure a durable and long-lasting tiled surface.