Applies to KEIM mineral silicate paint and stain finishes 

Mineral Silicate Finishes are extremely durable but like all exterior finishes do require routine maintenance to keep them looking their best. Depending upon the climate and weather conditions, the following recommendations for concrete, stucco, masonry and stone finished surfaces should serve as general guidelines.

Mineral Silicate Finishes provides more than just color to a masonry surface, it helps deter the effects of weathering, especially sunlight and wind-driven rain. The mineral finish should be evenly applied with no gaps or “holidays” with the masonry surface completely and uniformly covered. Generally, the more mineral layers you have the longer the mineral surface will wear and defend against weather. At a minimum two coats are required for full-service lifespans.

Frequency of maintenance

Exterior finish maintenance depends on many factors including the substrate (building’s surface), the environment and the exposure as well as the surface preparation and number of finish coats applied. Of these factors, climate and exposure usually play the biggest roles. In milder climates, finishes tend to last longer. Mineral silicate finishes typically last and look good for many years. While mineral silicate finishes do not fade, algae and bio-growth sometimes can occur in areas that are shaded and in areas of higher humidity and dampness where surfaces do not dry. Check shaded and northern and eastern-facing facades occasionally for bio-growth and algae. If present, this growth should be routinely removed to preserve the look and life of the finish.

Dealing with bio-growth

Bio-growth and algae should be removed from the painted surface when it is discovered. A solution of 3 parts water and 1part bleach is an ideal cleaning solution. Protect vegetation and wear protective clothing, gloves and eyewear. Dampen the affected area with a garden hose and liberally apply the bleach solution well beyond the affected area. A garden sprayer works well for this application. Allow the bleach solution to sit on the surface for 20 minutes, keeping the area wet by reapplying the bleach mixture as necessary. If scrubbing is needed only use a very soft bristle brush until growth is removed, being careful not to damage the mineral finish. Rinse the area from the bottom up, until the area is completely flooded with fresh water from a hose. NOTE: There are many commercially available cleaners and we also recommend the use of KEIM Biological Cleaner to remove stains from mold, mildew, algae, lichens and air pollution, especially on historic surfaces.

Pressure washing

Metallic Stains

Removing metallic stains due to water run-off from metal surfaces can pose a challenge. The blue-green patina/staining from water run-off of copper is difficult to remove, as are rust stains, which are typically reddish in color. Sure Klean® Iron Stain Remover is a specialized product developed for removal of copper and other metallic salt staining from natural stone, masonry, concrete, brick, and stucco surfaces that have been painted with mineral paints.

Chalky surface

Mineral silicate finishes do not “chalk” per se, but as the mineral silicate binder is eroded from the surface by the elements, particles of pigment may become “unbound” on the surface and give the appearance of a “chalky” surface. This situation usually does not occur in the first 20 years of the paint’s lifespan. This may be demonstrated by rubbing your hand or a rag across the surface. If you pick-up some of the color this is an indication it is time to repaint. Repainting mineral silicate surfaces is easy. Clean the surface using the methods above and reapply another coat of mineral silicate paint or stain. For maximum durability, you may elect to apply a second coat after 24 hours.

Touch-up

Touching up mineral silicate paints is a simple process. You will need the original mineral silicate finish of the same batch and the appropriate dilution (for stain only). To touch up a painted surface stir the mineral silicate finish until all pigment is fully dispersed and the paint is smooth and homogenous. Thin the mineral silicate paint or stain with up to 15% of the dilution. Dampen the surface area to be touched up to 12 inches beyond the touch up area. This will allow the touch-up mineral silicate paint to stay on the surface without drying too quickly. Apply the touch up paint in the same manner as the original application using as little diluted paint as necessary to cover the area. Using a quality paint brush, brush the edges of the touch-up into the damp area beyond to “feather” the touch up into the existing finish. Do not build up the touch up area as a difference in mineral finish thickness may be visible when it dries, especially when viewed from an angle. Always use as little touch-up finish as possible, applying in multiple thin layers if necessary and match the existing painted surface texture. For small nicks in the surface a stippling technique is also effective, try to limit the touch-up only to the damaged area.

Graffiti removal and protection

Mineral paint surfaces are inert, like a stone surface, but are micro-porous again like stone or concrete. Graffiti and other penetrating stains, like grease and oil, can become embedded in the mineral-painted surface. Graffiti can be removed using a chemical stripper like the KEIM Bio Stripper. Apply stripper and use a very soft bristle brush to work the area and clean using a pressure washer as described in this document. Penetrating stains like oil or grease can be removed with a detergent solution and a soft bristle brush and rinsed thoroughly. If the surface becomes damaged, recoating the area with one coat of silicate mineral finish may be required. Consult your KEIM representative to investigate the natural, vapor-permeable graffiti protection available from KEIM.

Refinishing KEIM mineral finishes at the end of the lifecycle.

After the useful lifespan of mineral finishes, recoating is a simple process. You can determine if your mineral finish requires a new coat by one of two ways. Visually if you see that the finish is beginning to lose color from areas that are most vulnerable to weather it is most likely time to recoat. Look for “run-off” of pigment onto the ground in these areas as another sign. You may also test the integrity of the painted finish by using your hand to rub across the surface to determine if color is coming off. If your hand picks up the color from your finish it is time to recoat.

Life Expectancy

These are very general guidelines and cannot address all the variables that affect the longevity of a painted surface. Every surface is different, and climatic conditions play a large role in aging. For example, the west and south-facing walls will be worn more quickly than their opposites. Use these general life expectancies as a guideline only.