Approved by Subject Editors on July 22, 2005
Reviewed by marycordaro
The Keim Mineral Systems paint line is one of the most sustainable, durable, protective, vapor permeable, and long lasting of all the natural paints on the market today. The product components of Keim paints are primarily a potassium silicate binder system with pure geologic mineral pigments. They are designed to penetrate and actually consolidate with substrates. (Only one of their many products contains a small amount of acrylic for better adhesion to exterior surfaces in highly humid areas.) The Keim products are also non-combustible, odorless and non allergenic, so they are great for the chemically sensitive, and an excellent, healthier option overall. Their impact to the environment from manufacturing is very low.
Because the Keim system was invented in 1878, there is actual proof that Keim paints last over 100 years, as seen on many building exteriors in extreme weather conditions in Europe. Designed for interior and exterior masonry surfaces, such as plaster, concrete, stucco, stone and other mineral substrates, they can also be applied to painted and unpainted paper covered drywall (with special prep, primer and application procedures). The colors are light reflective and colorfast, and the finishes create an attractive, flat, stone-like appearance. The finishes are 99% vapor permeable, even after a build-up of many coats, and including when used for exterior applications, yet their crystalline structure blocks wind driven rain, and protects against acid rain. The combination of water-resistance and vapor permeability also makes Keim an excellent paint for bathrooms and kitchens. (Excellent vapor permeability in finishes is highly desirable, so that moisture can easily and quickly move through and dry to either side of a wall, rather than becoming trapped and potentially causing finish failures and/or mold.) Because they are made with inorganic ingredients, the products are also mold resistant. Due to the absence of electrostatic charges from the painted surfaces, a benefit of natural finishes in general, the surfaces attract less dust, so they tend to stay cleaner. However, Keim paints are washable/scrubbable and easily cleaned.
The disadvantages of Keim paints are that they are not widely distributed, they are not appropriate for wood, metal or any flexible surfaces, and preparing existing painted surfaces, particularly on the exterior, may be extensive and expensive. In general, Keim paints are not ideally suited for surfaces that are already painted with multiple layers of other types of paints, whether water-based or oil-based. They should not be applied over finishes that act as vapor barriers, such as elastomeric, epoxy modified, or other paints designed to block or retard vapor transmission or chemical outgassing. Keim paints are much more expensive than conventional paints (about two and a half times the cost). However, since a Keim painted surface many only need a refresher coat every 20-30 years, for the right project, these paints are highly economical and sustainable over the long run.
Keim paints are most appropriate for new construction and/or previously unpainted interior or exterior substrates. For new interior drywall, the Keim company recommends first applying Ecosil Eco Dilution, which eliminates new drywall chalkiness, and then 2 coats of EcoSil finish coats. If painting over existing interior water-based paints, first apply EcoSil Grund (or base), then EcoSil finish coats. For previously painted oil-based surfaces, sanding to create a 'tooth' prior to priming is required. In either case, if there are already too many existing coats of paint, Keim may not be the right product, and the Keim technical expert can help make this determination over the phone. For exterior applications, it may be necessary to reduce layers of existing paint first, either by sanding, power washing or other means, to increase vapor permeability of the lower layers. (Before sanding any painted surface, always check first for lead-based paint. Do not disturb older layers of lead based paint, unless a trained professional implements proper lead-based paint abatement procedures.) The technical expert at Keim strongly recommends that the contractor or homeowner (whomever is actually performing the application) calls for detailed instructions, to first make sure that all particular considerations of the project are taken into account.
Keim paints are available in hundreds of colors. The company will also provide custom tinting. There are many types of products, each 'tweaked' for special situations and conditions. The Keim technical expert works closely with architects on specifications, as well as contractors, but will also work with the do-it-yourself homeowner to answer questions, and provide correct product recommendations and application procedures particular to the project.