Q.: What's the significance of percent solids in liquid membrane curing compounds? The cure-and-seal products seem to have a higher solids content. If two products meet the ASTM requirements for curing compounds, is the one with a higher percent solids more desirable?

A.: We asked Bill Phelan of Euclid Chemical Company to answer this one. He says high-solids curing compounds (about 30% solids) won't permit as much moisture loss. Curing compounds meet ASTM C 309 requirements if, at a coverage rate of 200 square feet per gallon, they hold moisture loss to 0.55 kilograms/square meter of surface in 72 hours. A high-solids curing compound at a coverage rate of 300 square feet per gallon typically allows a maximum moisture loss of only 0.30 kilograms/square meter. Curing is better because of the lower moisture loss.

Another advantage, according to Phelan, is that high-solids compounds are less likely to be applied too thin. It's easy to tell when the coverage is correct because the compound leaves a detectable gloss on the concrete surface. One caution: cure-and-seal curing compounds are excellent bondbreakers; don't use them if tile or other coverings are to be bonded to the floor.