Designed to penetrate the pores of the stone and prevent liquids from soaking into the stone. Helpful in keeping liquids out and lessen the severity of When an acidic solution comes in contact with the stone, a dull spot is the result. The acid “eats” the stone leaving dullness, or etching behind. Penetrating sealers help to reduce severity of etches, but cannot eliminate them. Depending on acidity, some liquids can etch immediately, such as wine, where milder acidic solutions may not etch with proper penetrating sealing. More, but will not prevent etching. This type of sealer will not alter the appearance of the stone in any way if applied properly.