Once you have decided on what type of sealer you want to use, the next step is determining if you want to use a water-based or solvent-based sealer. All sealers require a method of delivering the polymers to the material, whether it is going to be a surface coating (topical sealer) or going to penetrate into the pores of the material (penetrating and impregnating sealers).
The polymers are dissolved or dispersed in the carrier, either water or solvent, and then delivered to the material by the carrier. When the carrier evaporates, the polymers are left behind to react with the material to provide a protective barrier.
In most materials, solvent-based penetrating sealers and water-based penetrating sealers of a similar quality will offer comparable protection. In materials that are particularly hard or dense, like polished granite or porcelain tile, however, solvent-based penetrating sealers are often able to penetrate and be absorbed deeper into the material.
This is a result of solvent-based sealers having a lower surface tension than water-based sealers. Sealers with a low surface tension are able to penetrate more effectively in hard or dense materials.
Sealing Extremely Porous Materials
In extremely porous materials, solvent-based penetrating sealers can penetrate especially deep. However, this in turn can create a seal too deep to be effective. Applying multiple coats can overcome this, but can also end up be more costly. In today’s market, however, some manufacturers do produce solvent-based penetrating sealers that can also be used on more porous materials.
Color Enhancement and Scuff Resistance
Solvent-based topical sealers, or surface coatings, sometimes have better color enhancement properties and are capable of producing deeper and darker “wet looks” and glossier finishes when compared to similar water-based sealers. Solvent-based topical sealers, such as acrylic coatings, tend to be stronger than water-based ones, making them more scratch and scuff resistant.
Trickier to Apply and High VOC
While solvent-based sealers can penetrate deeper in dense materials and can have better color enhancement, they can be trickier to apply properly. They also tend to contain higher amounts of harmful VOC (Volatile Organic Compounds). VOCs emit gases that are harmful to people and the environment.
VOC gases can have powerful odors and fumes that require being used in well ventilated areas and with the use of a respirator mask. This can become problematic in indoor areas. Additionally, some states, such as California, have strict laws on the sale and transport of high VOC products, particularly in larger sizes of a gallon or more.