Understanding Clear Sealers
If you were shopping for stone to use on your floors, walls or counter top, and the dealer either could not, or would not tell you what kind of stone you were looking at, would you be concerned? Even if they said it was some kind of new, or miracle stone? Likewise with man made tile. Certainly the manufacturer has trade secret materials & processes, but you should at least know what class of tile you are looking at. Ceramic? Porcelain, Saltillo?
You would need this information to be able to make your decisions and comparison shop. The same holds true for clear sealers. Clear Sealers for stone & grout fall into three categories; Topical, Impregnating/Enhancing & Penetrating. All are useful and provide different types of protection and aesthetics. Topical sealers can be anything from a simple wax to a whole range of different polymers like acrylic, epoxy and many others. They may soak into the surface to improve adhesion, but they primarily sit atop the surface, providing certain properties and generally a very glossy, plastic like finish. Enhancers are typically resins that are used to soak into a stone and provide a "wet look" to enhance the color. A commonly used one is linseed oil but other polymers like silicone are currently being used. They will often leave at least a slight, subtle sheen from a thin residue of resin left on the surface. Penetrating sealers, sometimes called Impregnators, are designed to soak into the pores of a natural stone or masonry product and protect with very little to no change in the original appearance. They will not change the slip resistance of the original floor, for better or worse. They also allow water vapor to pass up through. The best of penetrating sealers are either based on fluoropolymer or silane/siloxane chemistries. Both are very small molecules that can penetrate deeply into the pores of the surface. Silanes are reactive and can chemically bond to certain surfaces. While great at repelling water, they can also react with hydrocarbons, e.g. oils, which makes them less effective against staining than other sealers. Silanes are often blended with siloxanes. Pure, 100% silanes are very low viscosity and can be used straight on many surfaces as a water repellent sealer. They are typically flammable and quite volatile, meaning much of it will evaporate before it can react and bond to the surface, plus they can be unpleasant to work with in an enclosed area. The raw material cost is moderate to high. |
Siloxanes are lower cost materials but are generally high viscosity and must be reduced with solvent, silane or emulsified to make them a usable penetrant. A blend of silane and siloxane is the most common type of approach for penetrating sealers.
Fluoropolymers are non-reactive. They will not break down under UV exposure and are quite chemically resistant. They are excellent at repelling oils which makes them better stain blockers than silicone type products. They also have very good water repellency, though not quite as good as silane/siloxane sealers. Fluoropolymers are solid materials in their pure form and must be either emulsified or dissolved in solvent to formulate them into clear sealers. Raw material costs are high and the final price of the sealer usually reflects the amount of polymer used in the formulation. Not surprisingly, none of these polymers are soluble in water. The simplest and most economical way to formulate the products was by diluting them with solvents. While quite effective, the down side of solvents hardly needs any explanation. The demand for water based versions started almost immediately. An emulsion is a mixture of two or more liquids that are normally immiscible (un-blendable). The word "emulsion" comes from the Latin word for "to milk", milk being an emulsion of milk fat and water. In a true solution, each polymer molecules is floating around freely in the solvent. An emulsion has "clumps" of polymer with a little coating of an emulsifier that keeps the clumps separate and allows them to stay suspended in the water. The better (yes, more expensive) emulsions have been able to reduce the size of these clumps to the point where for many applications they penetrate the pores of the surface quite deeply and perform as well as solvent based counterparts. Perhaps the only drawback is that they need to be applied in one coat, or at least wet-on-wet since they cannot penetrate a surface that is water repellent. Choosing the best clear sealer for your application will depend on three factors; desired appearance, required performance and the composition of the surface to be sealed. A good sealer should make it known the basic chemistry used for their product. Beware of products that rely only on buzz words like "nano", "miracle" or "break though technology". They don't need to reveal all of their hard work and trade secrets on the label, but they should provide some basic technical information along with the marketing dialogue, |