"All coal tar sealers are produced to meet federal specifications ... of silica sand per gallon to 5 lbs. per gallon. "The additional aggregate improves the performance of our sealer," Conwell ...

He says coal tar-based sealer can develop an odor of Hydrogen ... problem by adding a liquid biocide at a rate of roughly 1 - 1.5 gal. of biocide per 1000 gal. of sealer. He says asphalt-based ...