Concrete structures and masonry facades are susceptible to moisture intrusion due to porous substrate, shrinkage cracks and exposed uncoated areas exacerbated by wind driven rain. Entrapped moisture can cause spalling or other deleterious damage from within the substrate. A breathable coating system allows the substrate to dry out by outgassing moisture vapor whenever ambient conditions permit.

Si-Rex03 is a mineral-like coating and is accordingly just as breathable (water-vapor permeable). The microporous structure permits free movement of outgassing. Independent tests on Si-Rex03 show over 38 perms.

Highly permeable to water vapor, this critical Si-Rex03 function allows moisture to outgas easily; yet, all the while, the surface beading effect of Si-Rex03 repels water and prevents water absorption. Allowing entrapped moisture to escape stabilizes the substrate against deleterious outcomes such as ASR and/or DEF and breakdown of cementitious skim coatings.

The beading effect of silicone resin emulsion paints is apparent during rain and water run-off and is retained throughout the coating’s service life.

Si-Rex03 owes its great durability to the silicone resin binder that forms a hydrophobic (water-repellent) surface effect, the quartz-like structure of alternating Silicone and Oxygen atoms very resilient to UV exposure and chalking. Water repellent groups line the pores and stop the ingress of liquid water but allow vapor to outgas.

Dry facades are less prone to growth of microbes (mold and mildew) than damp ones. Silicone resin emulsion paints are less susceptible to dirt buildup than thermoplastic (e.g. acrylic) coatings; the “self-cleaning” effect due to rain will wash atmospheric dirt away. For structures in high heat, high humidity environments, Si-Rex03 is available in a “tropical mix” with additional biocides for enhanced protection against microbe growth.

The binder in Si-Rex03 comprises 50% mineral-type silicone resin and 50% polymer emulsion. The paint thus combines the useful properties of organic and mineral coatings in a single system.

Silicone resin emulsion paints have been used successfully from its invention over 50 years ago in Germany. More than a million buildings all over Europe, with many over 20 years without needing any further refurbishment let alone repainting, and structures throughout North America, Asia/Pacific and Middle East.

Provided they are suitably prepared and cleaned, most kinds of paint can be overpainted with Si-Rex03 including firmly adhering emulsion coatings (see also Question 15). However, to take advantage from Si-Rex03’s breathability, old coats of emulsion paint must be stripped off or removed mechanically.