Right now, for surface preparation, I find it better for old and new concrete walls to be applied first with 3 coats Boysen Plexibond, 3 coats of Davies Concrete Primer and Sealer, depressions to be levelled with skimcoat mixed with Concrete primer and sealer then sand to smoothen out (we did this after the first of 3 coats of Concrete primer & sealer), and then the final top/final coating of your choice. I selected Boysen Healthy Home for my top coat as my kids are asthmatic. I also plan to use the Boysen Virtuoso silk one time...