Acrylic Stains
For older stains can be applied only silicone paint (see below), but it is necessary to calculate the cost-effectiveness, since they are significantly more expensive than acrylic. Technological and operational properties of acrylic latex paint to a large extent depend on the content of the binder. At sufficiently high quality paints the binder is at least 15% of the volume, and the colors of the highest class comes to 40% or more. But at the same time, one should bear in mind that the higher percentage of binder, the lower water vapor permeability of the coating. Another very important factor – the dry rest – for high-quality acrylic latex paints are not must be less than 45-50% by volume. Both of these indicators significantly affect the price of paint.
Cheap latex paint (less than 2 $ / kg) have a high flow rate (kg / m ) and low durability, so their use not economically justified. So, if you want to create enough high-quality, resistant to pollution coverage, which does not meet high standards for water vapor permeability, the use of acrylic paint most appropriate. If the coating to high demands for water vapor permeability (such as painting buildings with poor foundations waterproofing) is advisable to apply the paint from a mixture of acrylic copolymer with a variance silicone resin. In these cases also use silicone or silicate paint. Silicate paints are mineral paints. A small amount of polymer (less than 5%) gives them stability in storage and possibility of using a mono version.
Silicate paint adhesion to the substrate with a two-step chemical reaction. At the first stage of the binder – a liquid potash glass – reacts with carbon dioxide in the air, forming a silica gel. In the second phase silica gel by chemical reaction meshes with a stone base. To align the absorbency of the base paint is used under silicate silicate primer also based on liquid potash glass. Silicate paints are used exclusively for coating mineral surfaces, for example, mineral plasters and surfaces previously coated with lime, cement or silicate paint. As for the polymer, they prevent the adhesion of liquid potash glass with a base and, consequently, impair the adhesion of silicate paints. Therefore, the surface of the previously painted with acrylic or alkyd paints, pre-cleaned of traces of previously applied coatings.