Yes and no - the answer depends both on the type of water-repellent and paint formulation used.
With the exception of Dynasylan® 100 NK and Protectosil ANTIGRAFFITI®, all Evonik products silane-based water repellents are compatible with most resins used in acrylic, epoxy or oil-based paints. A more important issue is the carrier, or solvent, employed in the paint formulation and its ability to "wet-out" and spread the paint evenly over the treated surface. Solvent-based paint formulations (with an alcohol, ketone, toluene, mineral spirit or other solvent carrier) will usually spread readily over silane-treated surfaces. Water-based paint formulations are more difficult, since wet-out depends on the type of surfactant used.
A surface treated with Protectosil ANTIGRAFFITI® may be easily cleaned with most commercial graffiti removers (follow manufacturers instructions) and a pressure washer. The protective coating remains undamaged even after repeated cleaning cycles.
Depending on the type of substrate, several (usually three) applications of undiluted Protectosil ANTIGRAFFITI® are required to achieve permanent protection. The surface must be allowed to dry completely between applications, this is dependent upon weather conditions but in general 30 - 120 minutes drying time is sufficient. More information is contained in the Technical Information on applying Protectosil ANTIGRAFFITI® (download from Literature page).
For normal dirt and grime, pressure-washing with or without a light-duty cleaning agent is typically sufficient. Mold or fungus should be removed with a sodium hypochlorite solution in addition to pressure-washing. Efflorescence and mineral deposits should be removed with a chemical cleaner specifically designed for that purpose, following the application instructions carefully, especially for neutralization and rinsing of the substrate.
It is recommended that new concrete and masonry be allowed to cure a full 28 days before applying silane-based water repellents.
Alkylslkoxysilanes are water-reactive molecules. This chemical reaction with water, known as hydrolysis, causes the silane-based water repellent to chemically bond with the substrate it is applied to.
Protectosil® and Dynasylan® products can perform this reaction with the naturally low moisture content of a "dry" substrate and penetrate deeply for long-lasting effectiveness. When hydrolysis occurs prematurely, the monomeric silane polymerizes and cannot penetrate the substrate effectively.
To avoid premature hydrolysis of silane-based water repellent products, Protectosil® and Dynasylan® products should be stored in their original, tightly-sealed containers in a dry storage area. All equipment should be clean and dry (preferably flushed with solvent before use). Never apply silane-based water repellents to a visibly wet or damp surface. Wait at least 48 to 72 hours of dry, sunny weather after pressure-cleaning a structure before beginning application of Protectosil® and Dynasylan® products.
Protectosil®, Dynasylan® products are penetrating water repellents.
They work by penetrating deep into the substrate, not by sitting on the substrate surface (the exception is Protectosil ANTIGRAFFITI®). Some of our products may produce a beading effect shortly after application, however, depending on environmental conditions, this effect may be short-lived (except in the case of Protectosil ANTIGRAFFITI®). However, the deep penetration of the silane into the substrate still provides full protection even if beading is no longer observed on the surface.
Protectosil®, Dynasylan® products are not toxic to plants. However, the alcohol solvent in some products may dry out the leaves of some plants, leaving brown spots where the product contacted the vegetation (no damage to roots is caused). It is therefore recommended to protect landscaping with plastic during application.
If water-repellent comes into contact with a glass surface, what should we do?
In general it is recommended to avoid contact between Protectosil® products and glass surfaces. Especially Protectosil® WS 405, Protectosil® WS 700 P, Protectosil ANTIGRAFFITI® and Protectosil® 100 NK will leave residue on windows and must be removed immediately if contact occurs. If a silane-based water repellent should contact a glass surface, remove it as soon as possible with a solvent. Water-based emulsions such as Protectosil® WS 405, Protectosil® WS 700 P and Protectosil ANTIGRAFFITI® can usually be removed from windows with standard window-cleaning products, if done promptly after application. Tar and/or bug remover designed for automobiles may be used to remove overspray from vehicles.