The ronseal one coat stain block can be used before painting to permanently block stains from showing through it covers nicotine crayon grease and much more permanently blocks stains in 1 coat and is ready to paint over in 4 hours before you start make sure youre in a warm well ventilated room all surfaces should be clean dry and free from dust mask any surrounding surfaces and repair any holes or cracks will the correct filler stir well before you start if youre using it to seal bare surfaces t