The scope of alcohol-based varnishes 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 composition of the varnishes contains resin dissolved in alcohol, the time for complete drying is no more than half an hour. Therefore, alcohol varnishes are called varnishes, which are obtained by dissolving natural resins in alcohol. Experts note that the coatings obtained by them are distinguished by high performance and aesthetic properties:
- long service life;
- mechanical strength;
- highly resistant to sunlight;
- pleasant shine.
On the basis of alcohol receive: shellac, rosin and carbinol varnishes.
Alcohol based shellac varnish
Shellac- This is a kind of resinous substance of plants prevailing in tropical and subtropical zones. Currently, it is 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 better as possible, it is carefully ground to obtain a fine-grained powder mass. Next, the resulting powder is mixed with 92-95% ethyl alcohol. To completely dissolve the resin, it is enough to heat the mixture to 20 degrees, periodically shaking the resulting mixture. The alcohol resin varnish obtained in this way should be well filtered to exclude undissolved inclusions and impurities. In this case, glass funnels equipped with ordinary cloth strainers are used as filters. The percentage of shellac in such solutions ranges from 30 to 45 percent.
Shellac spirit lacquer gives a fairly durable coating that is resistant to light, but it does not withstand temperature extremes and exposure to water.
Rosin varnish
Rosin is used as a basis for such varnishes. This is a vegetable resin obtained by processing a coniferous tree. The consistency of the rosin varnish is:
- 110g rosin;
- 20 g turpentine;
- 20g turpentine;
- 80 g 95% alcohol.
It is noteworthy that rosin serves not only as a base for varnish. It has been 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 as a result of the polymerization of a synthetic substance - dimethylvinylethynylcarbinol. From these resins, not only varnish is obtained, but also an adhesive used in construction work 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 on wood surfaces
These coatings are transparent and are able to give the surface shine 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 rather quickly and subsequently serve as a reliable protection of the treated surfaces from exposure to sunlight and adverse climatic factors.
Raw materials for the production of alcohol varnishes (sandarac, shellac, acaroids, etc.) are obtained not only in Russia, but also imported from abroad. The best quality varnishes are based on gummilac and shellac, which are widely used to coat wood and glass surfaces. Currently, technologists have learned to replace these resins with idiol, an artificial phenolic resin. Nevertheless, such a resin is inferior in quality to shellac alcohol varnish, it is not so durable and resistant to external stimuli. MoreIn addition, phenolic resins darken when exposed to light.
Alcohol-based varnish for wood lays down in a thin layer and creates a transparent film. To emphasize the structure on light wood, use only light paints.
Consistency of alcohol polishes
Depending on the amount of resin included in the composition, alcohol varnishes are classified into the following groups:
- Actual varnishes (more than 30% resin).
- Polishes (less than 30% resin).
For the treatment of wooden surfaces, mainly cloudy shellac alcohol varnish is used, which is not cleaned of wax. This is even an advantage, as the wax is excellent at sealing holes in the structure of wood surfaces.
In order for the quality of varnishes to be impeccable, when stirring the alcohol consistency, it is unacceptable to use parts that contain iron. When interacting with this element, the shellac solution turns black. Moreover, unwanted deposits are formed in it, which are not provided for by the technology for the production of varnishes.
The time needed to make polish is 3 to 5 hours. It takes longer to make the varnish, from 7 to 9 hours. More than a day (from 24 to 40 hours) will be required to make thick copal varnishes. In order to speed up the mixing process, the mixture is heated, while ensuring constant stirring of the solution.
Proportions of basic resin solutions
- Alcohol-soluble copal (60 kg of copal and 75-90 kg of alcohol).
- Gummilak (40 and 65 kg respectively).
- Rosin (60kg x 60kg).
- Birch bark resin (35-40 kg per 60-65 kg respectively).
- Sandarak (60 kg per 100 kg).
- Shellac (45kg x 90kg).
- Iditol (30-40 kg for 60-65 kg respectively).
To obtain the desired consistency, the listed solutions are thoroughly mixed and slightly heated. Solutions of sandarac and copal are used in lithographic varnishes and for surface treatment of musical instruments. Lithographic varnishes should provide a gloss to the processed materials and at the same time not be absorbed into the paper. Shellac varnishes intended for wood processing are not filtered. They are passed through a mesh made of copper. As a result of this treatment, mechanical removal of impurities is ensured.
