Great customer service by the actual manufacturer of the acid (not the seller). I called and spoke with the same person twice who gave me some great tips and ideas on how to get the best results. Be careful on how log you leave the stain on. We did a few test areas and when left on overnight the concreted turned almost black. At 1 hour my concrete reached a deep brown color. Not sure why but I'm happy with remote. Onto the sealer 2000!