Silicate-based paint (silacote) is a specially formulated type of inorganic, mineral paint. According to Silicate USA, a paint supplier, it's the most resilient paint technology available to protect concrete and masonry. The paint is produced from mineral compounds, like quartz, and inorganic mineral colorants that are combined with a potassium silicate binding agent. Unlike traditional paints that thinly coat the surface of concrete, silicate-based paint seeps into the masonry substance and creates a bond, making it less likely to crack and peel from exposure to the elements over time. Despite its advantages, silicate-based concrete paint has some problems.
Lacks a Closed Seal
Silicate-based paints do not have a closed seal to repel water, moisture and light when applied on surfaces, which means that the pigment in the paint is subject to the same environmental conditions, such as rain, wind and ultraviolet light from the sun, as the paint itself. Yet not all pigments are designed to hold up to these conditions. Certain silicate-based paints pigmented with inferior products can become discolored or show water spotting on the concrete surface. Look for a silicate-based paint colored with an inorganic pigment.
High Water Absorption
Silicate-based paints have high water absorption, which can impact the integrity of the concrete surface in the long term. According to Adrian Thomas, FTSC of Chemicalia Pty Ltd and author of "Waterborne Silicates" (a white paper), to lessen water absorption painters should combine these paints with a water repellent or the addition of an impregnation with a water repellent applied as a final coating to the painted surface. The water repellent, however, must only be applied as the final coating; otherwise it can impact the adhesion of the paint.
Does Not Adhere to Certain Over Painted Surfaces
Silicate-based paints do not adhere to polyurethane unless a wetting agent is used. For the best results, silicate-based paint must be applied with a self-primer or adhesion adapted for acrylic paints that includes a wetting agent. Otherwise, the silicate-based paint can peel and crack. In addition, remove old coats of emulsion paint before using the silicate-based paint to ensure the paint's breathability is not compromised.