To Seal, Or Not To Seal

As a contractor in the stone and tile industry, one of the most common services that we’ll be asked to provide will be the sealing of the tile and grout surfaces. While this service provides very high profit margins with minimal effort, knowing when a sealer is applicable and passing that knowledge onto your customers is a sure way to gain trust and the reputation of the true stone professional in your area. To better determine when sealers are, and are not applicable, it is important to understand how the sealer performs and what they are actually doing to the surface being sealed.

Clear penetrating sealers, most commonly referred to as “impregnators”, are offered in a variety of designs for protection from oil and water based stains of many types of surfaces. They are actually a two-part product; the first part being the carrier of the sealer, typically a water or solvent molecule, and the second part being the “resin”, or the solid that is actually clogging the pores of the stone. Natural look sealers (TECH SEAL, MAX GUARD, SELECT SEAL, and RAPID SEAL) and enhancing sealers (REVEAL & SEAL, ENHANCER) are all categorized as “penetrating”. These sealers are designed to “penetrate” past the surface tension of the substrate and fill the pores below, effectively blocking out other liquids.

So what should be sealed using an impregnating sealer? Simply put, every surface that it is absorbent. The biggest misnomer in the industry is that all natural stone is absorbent and therefore every stone needs to be sealed. Most granite, a large variety of marbles, and even some travertine have such a tight crystalline structure that even the highest quality solvent based sealers are unable to penetrate past the surface tension. These surfaces are tightened even further during the polishing process making the stone almost impenetrable. This is not to say that you should stop offering sealing for these types of surfaces. Many times your customers are going to have natural stone flooring that has not been brought up to a high polish or are purposely brought down to a completely matte finish. In these instances a penetrating sealer will be effective almost every single time. So how do we decide which stones should and which stones shouldn’t be sealed? It’s simple. Put water on the surface and find out if it absorbs. This absorption will be obvious as the surface will darken almost immediately as the water touches to the stone. A lot of times, during the bidding process, I’ll take a terry cloth and get it wet. I’ll then fold it into quarters and set the damp cloth on the areas that are to be treated. After measuring the area and answering any questions that the homeowner may have, I pick up the towel and look to see if that area has darkened. It will be very obvious at that point whether or not you should recommend sealing to you customers. If there is a dark square where your damp cloth was, they will benefit from a sealer. If not, they probably won’t.
Here is a list of some common surfaces that you’ll run into and whether or not they should be sealed. Make note that there are no absolutes in this industry and that all surfaces should be tested for their absorbency rate regardless of the material.

“Shoulds”
• All cementacious grout, both sanded and un-sanded
• Limestone
• Tumbled marble
• Honed marble
• Flamed granite
• Tumbled travertine
• Honed travertine
• Slate
• Saltillo
• Brick
• Concrete
• Flagstone
• Sandstone

“ Should Nots”
• Epoxy or Acrylic grouts
• Polished granite
• Polished travertine
• Polished marble
• Ceramic tile
• Polished terrazzo
• Cultured stones
• Color coated grout

So once you have determined whether or not the surface should be sealed, choosing the right base of sealer is the next important step. I get asked all the time, “which sealer is the best to use?” As mentioned earlier, there are typically two types of sealer bases; water and solvent. So how do we determine which sealer is better? The solvent based sealers are almost twice as much as the water based version, so certainly they must be better, right? Not necessarily. In fact, the chemicals used to seal or enhance the surfaces that you’re restoring are the exact same in both the water and solvent based. The difference between the two lies solely in the molecule that carries the chemical into the surface that is being sealed. With the solvent molecules being so much smaller, they are going to be more effective in penetrating past the surface tension of the denser stones like marble, granite, and travertine. Whereas, more porous surfaces such as brick, grout or Saltillo will absorb the water based sealers just as effectively. Once the carrier has evaporated, the sealing component remains in the pores of the stone leaving the surface resistant to staining. Here’s another list for you guys to help you determine which sealer is going to work best for your particular project. As always, I will recommend that you do an absorbency test on the areas that you will be sealing to make certain that you are choosing the right option.

Should Use Solvent
• Granite
• Travertine
• Quartzite
• Polished concrete
• Marble
• Polished limestone
• Slate
Should Use Water
• Sandstone
• Honed limestone
• Flagstone
• Stucco
• Saltillo
• Terra Cotta
• Clay brick
• Honed concrete
• Cementacious Brick
• Grout

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