The scope of varnishes made on the basis of alcohol is quite wide. In particular, the industry has mastered the production of this paintwork material for coating various products:
- interiors and facades of buildings;
- furniture;
- glass surfaces;
- genuine leather products;
- other surfaces.
Due to the fact that the varnish contains resin dissolved in alcohol, the time of complete drying is no more than half an hour. Therefore, alcohol is called varnishes, which are obtained by dissolving natural resins in alcohol. Experts note that the coatings they receive are distinguished by high operational and aesthetic properties:
- long service life;
- mechanical strength;
- high resistance to sunlight;
- pleasant shine.
On the basis of alcohol receive: shellac, rosin and carbinol varnishes.
Alcohol Based Shellac
Shellac is a type of resinous substance of plants prevailing in tropical and subtropical zones. Currently, it has been widely used in the manufacture of varnishes and plastics. Due to its unique properties, shellac is able to dissolve well in alcohol. In order for the resin to dissolve as quickly and as best as possible, it is carefully ground to obtain a fine-grained powder mass. Next, the resulting powder is mixed with 92-95 percent ethyl alcohol. To completely dissolve the resin, it is enough to warm the mixture to 20 degrees, periodically shaking the mixture. Thus obtained alcohol varnish with resin should be well filtered to exclude undissolved inclusions and impurities. In this case, glass funnels equipped with filter cores from ordinary cloth are used as filters. The percentage of shellac in such solutions is from 30 to 45 percent.
Shellac alcohol varnish gives a sufficiently durable coating that is resistant to light, but it does not withstand temperature extremes and water.
Rosin Varnish
Rosin is used as the basis for such varnishes. This is a vegetable resin obtained by processing conifers. The consistency of rosin varnish is as follows:
- 110 g of rosin;
- 20 g of turpentine;
- 20 g of turpentine;
- 80 g of 95% alcohol.
It is noteworthy that rosin is not only the basis for varnish. It is successfully used as a base substance in the production of mastic.
Rosin alcohol varnish has a low cost, but its coating is not durable.
Carbinol lacquer
The basis of these varnishes are carbinol resins obtained by polymerization of a synthetic substance - dimethylvinyl ethinylcarbinol. From these resins, not only varnish is obtained, but also glue used in construction works and in industry. At a temperature of 20 degrees, this varnish dries on the surface of the processed products in an hour and a half. Depending on the composition, carbinol alcohol varnish is colored or colorless.
Varnishes used for processing wooden surfaces
Such coatings are transparent and able to give surface gloss and emphasize the natural texture of wood. Alcohol varnishes for wood are widely used in the furniture industry. Since they are based on ethyl alcohol, they dry out fairly quickly and subsequently serve as reliable protection for the treated surfaces from exposure to sunlight and adverse climatic factors.
Raw materials for the production of alcohol varnishes (sandarak, shellac, acaroids, etc.) are obtained not only in Russia, but also imported from abroad. The best quality are varnishes obtained on the basis of gummilak and shellac, which are widely used for coating wooden and glass surfaces. Currently, technologists have learned to replace these resins with idiol, an artificial phenol-aldehyde resin. Nevertheless, this resin is inferior in quality to shellac alcohol varnish, it is not so strong and resistant to external irritants. Moreover, phenol-aldehyde resins darken in the light.
Alcohol-based varnish for wood lays in a thin layer and creates a transparent film. To emphasize the structure on light wood, only light coatings should be used.
Consistency of alcohol varnishes
Depending on the amount of resin included in the composition, alcohol varnishes are classified into the following groups:
- Actually varnishes (more than 30% resin).
- Varnishes (less than 30% resin).
For the treatment of wooden surfaces, mainly muddy shellac alcohol varnish is used, which is not cleaned of wax. This is even some advantage, as the wax is able to perfectly plug holes in the structure of wooden surfaces.
To ensure the quality of the varnishes is impeccable, when stirring the alcohol consistency, the use of parts containing iron is unacceptable. When interacting with this element, the shellac solution turns black. Moreover, unwanted precipitation is formed in it, not provided for by the technology for the production of varnishes.
The time required for the manufacture of polishes is from 3 to 5 hours. It takes more time to make the varnish, from 7 to 9 hours. More than a day (from 24 to 40 hours) will be required for the manufacture of thick kopalovye varnishes. In order to make the mixing process faster, the mixture is heated, while ensuring constant stirring of the solution.
Proportions of resin solutions
- Alcohol-soluble digging (60 kg of digging and 75-90 kg of alcohol).
- Gummilak (40 and 65 kg, respectively).
- Rosin (60 kg to 60 kg).
- Birch bark resin (35-40 kg per 60-65 kg, respectively).
- Sandarak (60 kg per 100 kg).
- Shellac (45 kg to 90 kg).
- Iditol (30-40 kg per 60-65 kg, respectively).
To obtain the desired consistency, the listed solutions are thoroughly mixed and slightly heated. Sandarak and digging solutions are used in lithographic varnishes and for surface treatment of musical instruments. Lithographic varnishes should ensure the gloss of the processed materials and not be absorbed into the paper. Shellac varnishes designed for wood processing are not filtered. They are passed through a grid made of copper. The result of this treatment is the mechanical removal of impurities.