Application of AcryShield® Roof Coating over Asphalt Emulsion
Standard clay type asphalt emulsions, including those modified with various resins, typically contain surfactants. Surfactants are surface active agents needed to properly mix particles during manufacturing and to provide stability of the product after packaging.
After application of the asphalt emulsion, surfactants are drawn by moisture to the surface, leaving a soapy residue. After drying out, this residue will appear slick on your fingers when rewetted.
Surfactants may be drawn out of the applied coating by heavy fog, dew or light rain. Then they are often carried by moisture to low areas on the roof.
After drying on the surface, surfactant residues are easily removed by heavy rain or by washing the roof off with water.
Due to this inherent characteristic of asphalt emulsions, great care must be taken prior to applying AcryShield over the emulsion. Surfactants left on the surface will inhibit proper adhesion of AcryShield over asphalt emulsions.
Various options exist to avoid adhesion problems. They include:
Apply AcryShield before moisture has a chance to draw out the surfactants.
Apply AcryShield after heavy rains have washed the surfactants off the surface. In this case, moisten the low areas of the roof to check for any remaining soapy film.
If surfactant problems are suspected, wash off the roof with water, rinsing especially the low areas, prior to coating with AcryShield.
In hot, dry climates, such as in desert areas during summer, there is less chance for these types of surfactant problems to exist, even if the emulsion is left uncoated for many days. Use appropriate judgment in all cases to ensure a good system application with adhesion integrity.
For further information, please contact a National Coatings Technical Consultant.