Practical Considerations for Making Low-VOC Silicon-based Water Repellents

By David B. Selley

Among ways to protect concrete, natural stone, and masonry structures from degradation, the use of water repellents has proven to enhance durability significantly, due largely to the fact that water is the most damaging environmental assailant to structures made from these materials. Of course, in order to provide long-term protection against the damaging effects of water, the protective treatment itself has to have good durability.

Silicon-based products cover a variety of chemistries, but the main feature of most silicon based products is their ability to resist degradation from oxidation, UV exposure, and—in many cases—pH extremes. In the more specific case of silicon-based water repellents, the ability to penetrate below the surface of the treated substrate also enhances durability, because the treatment will not wear away from friction or abrasion.

Another important aspect to long-wear and excellent performance of any treatment is the ability to bond to a substrate. In the case of silicon-based water repellents, an actual chemical bond is created when the silicon-species reacts with and forms a covalent bond to the substrate.