The graying is caused by sealcoating drying under less than ideal conditions, e.g. shaded areas, cooler temperatures, high humidity, etc. The problem is mostly temporary i.e. after a few days in full sun it will cure to its normal color. Temporary graying can also be eliminated through the use of specialty additive that helps sealcoating dry faster and at a uniform rate. If the problem persists and the sealcoating does dry to its characteristic charcoal black color, the manufacturer should be consulted.