The way in which mineral silicate paints work is that they penetrate the mineral substrate to which they are applied onto, such as renders and concrete, forming a chemical crystalline bond with the substrate. The nature of the crystalline structure formed is that of an insoluble silicate similar to silica sand on a microscopic scale and as such is highly resistant to both strong acids and strong alkalis. Because of the crystalline nature of the coating, compared to a conventional film forming coating produced by an oil based paint system, there are finite gaps between adjacent crystals, these ‘holes’ are large enough to allow the free passage of vapour but small enough to prevent the passage of driven rain. This therefore means that the Keim coating becomes an integral part of the mineral substrate to which it is applied onto and maintains the substrate vapour permeability, whilst at the same time providing an effective barrier to the ingress of moisture. This process means that the paint system takes on the same co-efficient of expansion as the mineral substrate to which it is applied, allowing existing or any possible future structural defects to be effectively monitored. Whilst the final visible appearance is described as matt, the crystal structure provides excellent light reflectance characteristics which can satisfy lighting performance requirements in a wide variety of shades. In addition, through the addition of earth oxide pigments there is no colour fade with the passage of time – this having been verified on buildings that were decorated over 100 years ago where there is still no discernible colour fade, as well as no breakdown of the coating itself. Keim Mineral Paints are inherently resistant to mould and fungal growth because of their high alkalinity, (pH is approximately 12.3), and therefore will provide longterm resistance to mould and fungal growth. Keim Silicate Paints contain neither solvents nor any petro-chemical derivatives, are inherently non-combustible and do not give off any toxic gases. As well as having achieved a Class 1 rating to BS 476 part 7, with regard to surface spread of flame and a fire propagation index of 2.7 in respect to BS 476 part 6, giving a Class 0 surface, Keim Mineral Paints have been assessed by London Underground Transport for use in underground railway stations and have gained full approval in that they do not support spread of flame, nor do they add any noxious omissions during the course of a fire. With regard to dirt and dust deposits on painted surfaces, if one considers conventional oil based paint systems, these inherently have a negative electrostatic charge on their surface and will therefore attract dust from the atmosphere. Keim Silicate Paints do not have any such residual negative charge on their surface and therefore the rate at which dust accumulates is less that that on a conventionally painted surface. However, there will be a need from time to time, to clean the decorated areas in order to maintain satisfactory light reflectance values and a generally good aesthetic appearance. In this respect Keim Paints may be periodically power washed, either on a six or twelve monthly cycle basis. Keim Paints are unaffected by detergent mediums, and will give a satisfactory longterm performance. With regard to the overall performance of the coating system, as previously mentioned there are examples in existence of the Keim Silicate Paint system lasting for periods in excess of 100 years in the harsh climates of Southern Germany, Switzerland and Norway.
