"I have been a painting contractor for many years and the first time I used Loxon XP I was really impressed. But........if you want it or any other type of paint to last the surface must be clean. Mildew, mold, efflorescence, dirt and everything must be completely eliminated. I power wash the surface and use a cleaner when needed. I usually let the masonry sit for 3 days at a temperature at or above 65 degrees. I like the masonry to be completely dry. For foundations in decent to good shape I still use Loxon Conditioner for a primer which penetrates and seals exterior surfaces and bonds light chalk to the surface. For older masonry surfaces I use either Loxon Block Surfacer or even Heavy Duty Block Filler. When the primer is completely dry I always use two coats of Loxon XP. If the first coat is not applied thick enough or rolled or brushed to quickly it will leave pin holes which gives moisture a way in. A second coat will take care of that and give the surface a hard smooth flat finish. I have used one just coat of Loxon XP in newer applications and it still looks great today. I have never had to go back and re-due a Loxon XP job. I learned long ago that the more time you spend on the prepping of a job the longer your paint or covering will last."