Penetrating sealers and impregnating sealers (a type of penetrating sealer that penetrates deeper) protect the stone or other material by penetrating into the pores and below the surface. Solid particle are then deposited to coat the individual minerals.
These sealers can be either solvent-based or water-based and contain polymers such as siliconates, fluoro-polymers, siloxanes, silanes, or other blend of polymers that will coat the pores of the material.
Protecting the Material
By penetrating into the pores of the material, the sealer is able to protect the material from below the surface against water stains (coffee, tea, soda, etc), oil stains (cooking oil, grease, body oil, etc), and from dirt. These sealers will also help to protect against mold, mildew, soap scum, and other penetrating items. Penetrating sealers offer varying degrees of protection against moisture and stains, depending on how the sealer is designed to work.
Some sealers have protection against just water (hydrophobic) while others provide protection against both water and oil (oliophobic). Furthermore, some sealers are just resistant toward water or oil stains, slowing the absorption rate into the material, while others may be repellant, preventing the liquid from entering the material.
Because these sealers do not leave a surface coating, they do not provide protection on the surface from physical damage including scratches and abrasions. They also will not protect against acid etching resulting from lemon, vinegar, tomato, and other acidic foods and drinks. Penetrating sealers designed for exterior use are generally not affected by UV light.
Preserves Natural Look
Most penetrating sealers are designed to preserve the natural look of the material being sealed by not altering the appearance. Some penetrating sealers do contain an enhancing agent that will enrich the natural colors in the material but will still maintain a natural look. Unlike topical sealers, penetrating sealers are not designed to alter the surface finish of the material, such as by adding sheen or a glossy finish.
Expected Wear and Maintenance
Penetrating sealers have a much longer life expectancy than topical sealers. Some sealers will last for a year while others have an expected wear of 5 years or more. Expected wear depends on the particular sealer being used and the area being sealed. Regardless, all penetrating sealers will eventually lose their strength and bonding to the pores in the material, evaporating away.
High traffic areas and improper cleaning procedures will cause the sealer to wear off more quickly, resulting in the sealer losing its ability to protect. While not subject to the same wear and tear as topical sealers, foot traffic still causes the sealer to wear off more quickly. Overtime, foot traffic causes the surface to be worn down and for the pores of the material open, allowing the sealer to evaporate.
Using a proper cleaner that has a neutral ph balance will help to extend the life of the sealer. Cleaners that are high alkaline can break down the sealer and ones that are acidic can not only break the sealer down more quickly but also damage natural stone with etching. Some cleaners will also contain a built-in sealer that will help to replenish the sealer in the material and are ideal as a way to “top off” the sealer to extend its life.
Typically, will not change the appearance of the material so that a natural look is preserved.
Long lasting from a 1 year to 5 years or more, depending on the particular sealer being used and the area being sealed.
Can be water resistant or repellant or both water and oil resistant or repellant.
Most are UV transparent and not affected by UV light.
Often, material can still “breathe,” allowing moisture and vapor to escape.
Good quality penetrating sealers can be expensive.
Will not protect the surface from physical damage such as scratches and acid etching.
Solvent-based sealers can be tricky to apply and can release harmful vapors during application.