Info from <a href="http://hytechsales.com/download/HiTemp%20Product%20Description.pdfQuote:Surface">http://hytechsales.com/download/HiTemp%20Product%20Description.pdfQuote:Surface</a> Preparation: All surfaces must be sound, dry, clean and free of oil, grease, dirt, mill scale, and any other surface contaminants.