Open time, sometimes called flash time, describes the amount of time that we want the freshly troweled adhesive to remain open to the elements before you start installing floor covering. There is a good reason why open time needs to be followed: Many water-based adhesives need a little time to start evaporating and letting some of the water out before you start installing flooring. Moisture-curing adhesives need to be exposed to atmospheric humidity to get the reaction started. Again, if you start installing before allowing for the recommended open or flash time, you run the risk of a delayed curing time, which can lead to placement problems and long-term performance issues.

After treating corners and seams of cement board with mesh tape and a polymer-modified, cement-based tile mortar, the area should be allowed to cure for at least 24 hours before the application of MAPEI’s Mapelastic AquaDefense. Note: If time is an issue, use a MAPEI rapid-set, polymer-modified mortar with the mesh tape and allow the area to dry for at least four hours before the application of Mapelastic AquaDefense.

This term refers to the amount of time, after the open time or flash time (if any), during which the adhesive you just applied will accept the flooring material and still provide an adequate bond. If you leave certain adhesives open to the atmosphere for too long, they will skin over or cure out and not be wet/sticky enough to accept the flooring material. In other words they will dry out. It is important to note that working time is often affected by the ambient temperature as well as the ambient humidity. For example, in arid parts of the country when the temperature is very high, working times will be much shorter for water-based materials but much longer for moisture-curing materials. Areas of high humidity and high temperature will have longer working times for water-based materials but potentially shorter working times for moisture-curing products. Cold temperatures are going to slow everything down whether the products be water-based or moisture-curing. For reactive adhesives like epoxies or epoxy-modified polyurethanes, temperatures will greatly affect the working time. Reactive adhesives are very sensitive to temperature, so cold conditions will extend the working time and hot conditions will speed things up.