The product claims to be an economical, easy-to-apply, penetrating sealer that resists most common oil-based and water-based stains. Unlike other sealers, it will not leave a difficult-to-remove residue on the surface. Low-odor, water-based formula. Water sheds off ceramic surfaces and this has worked on even highly porous clays having up to 25% porosity.
Outdoor Weather Resistant Ceramics
How can you be sure that the porosity of your fired ceramic ware is low enough to prevent freeze-thaw breakdown in the winter?
Many ceramics are either porous by nature or by necessity. For example, stonewares need to be non-vitreous enough that they do not warp or blister on firing. Red earthenwares must be porous in order to have the red color (they go brown when fired higher). White talc or dolomite low-fire clay bodies always have high porosity. Bricks must have minimal firing shrinkage, which guarantees substantial porosity. Even porcelains can blister and it is common to cut back on feldspar to give them more margin for overfiring - that brings porosity. If water penetration must be prevented all of these need to be sealed, these are some of the methods.