Pavetuf PTSLIV5L 5L Invisible Sealer - Invisible Sealer is a non-film forming impregnating treatment. This advanced water based formula allows you to seal your paving immediately after installation and allows efflorescence/salts and moisture to pass from the mortar bed through the paving. This sealer is an environmentally friendly product, completely waterborne, non-toxic, solvent and silicone free.