Lacquer coating for plaster tiles

Gypsum tiles (alabaster, selenite), due to many advantages, are a common decorative finishing material.

Using a special coating for tiles, you can make an individual design

Here is an incomplete series of positive properties of alabaster and products from it:

relatively small specific gravity;
the possibility of manufacturing products of any configuration by casting with their own hands;
ease of processing and fitting alabaster tiles and stucco;
fire resistance;
environmental friendliness;
dielectric properties;
resistance to chemicals;
ease of restoration work;
the possibility of artistic design of products.

However, gypsum also has serious drawbacks that impose restrictions on the use of selenite tiles:

hygroscopicity (the ability to accumulate moisture from the environment);
low moisture resistance (destroyed by prolonged direct contact with water);
low impact resistance (even a light blow will leave a chip or shell on the surface).

If you originally thought of a light coating, you need to consider that the varnish gives some darkening

These shortcomings make selenite tiles unsuitable for outdoor finishing work and cladding of rooms with high humidity and, especially, open contact with water.

Applying modern technologies for additional processing of gypsum tiles, you can minimize these shortcomings and successfully apply gypsum finishing not only in dry rooms, but also in rooms with seasonal fluctuations in humidity.

Improving the performance of gypsum finishes

Manufacturers of alabaster cladding most often offer the consumer products that have already gone through the process of improving performance and are varnished. The price of such material is higher due to the cost of additional processing. Knowing the optimization technology, you can purchase gypsum cladding without protective treatment, for example, the popular hand-made Monte Alba decorative cladding tiles, and independently improve the properties of the material, and then varnish it. Consider what is the pre-treatment of gypsum products before applying varnish, types of varnish compositions and methods of their application.

Impregnation of gypsum tiles with hydrophobic agents

To neutralize the hygroscopicity of gypsum products, they are hydrophobized, which consists in impregnation with water-repellent compounds (water repellents) based on organosilicon polymers. Due to the deep (up to 20 mm) penetration of water repellents into gypsum without the formation of a film, porosity decreases, but the vapor permeability of products remains, the degree of hygroscopicity and the susceptibility of tiles to mold decrease.

Water repellents are offered by manufacturers in the form of ready-to-use solutions, as well as concentrated formulations that require dilution. The method of application is indicated on the packaging of the mixture.

The general requirement for the use of hydrophobic compounds is to apply them to a completely dried gypsum tile, cleaned of dust. Gypsum products are processed from all sides in two layers, until saturation, without waiting for drying. This method of processing reliably isolates the cladding not only from the humidity of the outside air, but also from the moisture of the base material. For application, depending on the area of the treated surface, a brush or roller is used.

Water repellent Tiprom

Processing should be carried out in goggles and gloves, avoiding contact with the composition on exposed skin. Contamination of neighboring glass and metal parts with a water repellent must be removed in time, as the composition quickly hardens.

water-repellent silicone composition White Hill;
silicone impregnation "Optimist C405 - Natural stone";
a number of water repellents "Tiprom".

Impregnation silicone water-repellent – Natural Stone

Lacquering plaster finish

After hydrophobization of alabaster tiles, the base is clad by laying gypsum products on an adhesive mixture selected in accordance with the type of wall surface. A day after the end of laying, they begin to decorate the finish with paints.

To protect the artistic layer of the cladding, it is necessary to cover the tile with a protective varnish layer. This operation is started after the end of the decoration, but not earlier than 5-10 days after the end of the laying of the tiles, so that the tile adhesive under the finish not only hardens, but also dries.

To apply a protective coating of gypsum tiles, acrylic or oil varnish is used. These materials differ in properties, so we will consider each separately.

Protection of alabaster tiles with acrylic varnish

Acrylic lacquer is a ready-to-use aqueous dispersion of resins, a milky-colored liquid, which is applied to interior and exterior finishes for protective and decorative purposes. This solution is resistant to cracking, forms a strong, transparent film on the surface, which, after drying, can be removed with a special solvent.

Acrylic-based coating is resistant to detergents, moisture and ultraviolet, temperature fluctuations. The composition is odorless, harmless to humans and the environment, dries quickly, becoming transparent. Acrylic varnish is diluted with water to the desired consistency and applied to the surface with a brush, roller or spray gun.

Lacquer for natural and artificial mineral surfaces

Acrylic varnish is available in three types: glossy, matte or semi-gloss.

When applying a gloss mortar to gypsum tiles, be aware that the cladding will receive sheen and highlights from the lighting, which will distort the colors of the tile decoration.

Matte acrylic lacquer will retain the velvety surface of the tile, which imitates rough-cut natural stone, without changes. This composition is an ideal protective coating for Monte Alba tiles.

The semi-gloss variety of varnish, in terms of its effect on the lining, occupies an intermediate position between the two types described.

When dried, a thin film is formed, which prevents moisture from being absorbed into the gypsum

When decorating gypsum cladding, which was painted with water-based paints, 10% acrylic varnish can be added to the emulsion to enhance adhesion to gypsum. After coating with two layers of such paint, only one layer of varnish can be applied to the alabaster tile.

Important! If you do the opposite, add paint to the acrylic solution, then the coating will turn out with stripes of the color of the paint, which is not always desirable.

An example of a successful choice of a protective and decorative coating for gypsum finishes is the paint and varnish products of the Finnish company Tikkurila.

Coating gypsum tiles with oil varnish

Oil varnish is a solution of natural or artificial resins in vegetable oils. After applying to the base, such a varnish first forms a film on the surface of the layer, and then dries over the entire thickness and serves as a strong protection of the surface from mechanical and physical damage.

Oil varnishes, like acrylic, are produced in glossy and matte. To bring the solution to the desired consistency, special thinners are used that do not change the characteristics of the varnish. Oil varnishes are produced colorless or transparent, but having some shade, therefore, when choosing a material for coating gypsum tiles, one must take into account the compatibility of the varnish shade with the color of the alabaster finish. All oil solutions, including colorless ones, darken a little after drying, which must also be taken into account when decorating gypsum tiles.

Yacht oil varnish provides the most durable coating, so its use to protect gypsum cladding is most appropriate. Lacquer after thorough mixing with a thinner is applied to the finish with a thin layer with a brush or roller. The solution should be well distributed over the surface, avoiding the formation of streaks. Yacht varnish dries, depending on the temperature of the room, for about a day.

Lacquer for gypsum tiles - an indispensable thing to give the surface the desired shade or glossy sheen

After the first layer has dried, the lining is inspected for the presence of streaks, which must be carefully sanded with fine sandpaper before applying the second layer. The second coat of lacquer also dries for about a day, after which the lacquered finish is wiped with a clean, damp, soft cloth to eliminate residual adhesion.

Decorative tiles "Monte Alba", covered with a protective layer of yacht varnish, despite the corrugated surface, are easier to keep clean and last longer.

Conclusion

There is an opinion that finished gypsum tiles that have been processed do not need to be varnished. But in this case it is not known what quality of varnish was used. Therefore, an additional layer of colorless matte acrylic or yacht varnish will not be superfluous and will only add strength to the protective coating of the tile.

If you don’t want to spend money on varnish, then the finished alabaster tile “under the stone” can be covered with a layer of wax, which will also serve as additional protection against mechanical damage and pollution.

As for Monte Alba tiles and the like, which are sold without a protective coating, it is necessary to varnish them for protective purposes.