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    June 2021
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    Surface finishing agents

    Surface finishing agents

    Currently, a wide range of varnish products for wood with different composition and properties is produced, different preparation methods and different properties of the coating. It can be said at the outset, that roughly, multi-layer coating is always better. The unsightly appearance of the thin varnished coatings can be observed on the furniture, in which the matt surface is achieved by using only nitrocellulose lacquer. The pores in the wood are not closed, dust enters them and causes them to darken, and then the surface becomes gray. Only hard wood species, and it is carefully sanded (graining 100 or 120), can be coated with a thinner layer of varnish.

    Wood panels have a lot to do with furniture. In many cases, they complement the furniture surfaces, or they are an independent part of the interior or even the exterior walls. In the furniture industry, we have encountered a matte finish more and more often recently. This gives the wood a more natural look, it deprives them of light reflections.

    However, let's not cross the shiny surfaces of the wood - it's all about a hundred-year-old tradition, that shaped the flavor, and if someone likes shiny wood, he has a number of good resources at his disposal to satisfy his own preferences. However, one should not forget about the necessity to respect the principle of thorough smoothing of the surface before painting. This need is twice as necessary, if you want a good effect.

    The number of layers of the varnished coating is very important. Two layers of varnish are the minimum necessary, even with varnishes with a high dry matter content. However, when painting outdoor items, three layers of coating are required.

    The first layer is actually an adhesive backing. Most of the first coating layer penetrates into the pores of the wood. Some exterior varnishes use a single coat, a very thin varnish foundation.

    Before applying another layer of varnish, gently sand the well-dried previous coat with fine sandpaper, grain size 80 or 100. This step is very important, but it is often overlooked. In this way, protruding wood fibers are removed, hardened after applying the first coat of varnish, impurities from the brush as well as dust from the air. As a result of sanding, all irregularities are removed and the surface remains smooth. The omission of sanding results in copying all irregularities when applying a further layer of varnish and leaves a shiny but rough surface.

    When sanding the varnished layer, the coating is scratched, which loses its shine. However, it is not essential, because after applying a further layer of varnish, the surface will regain its shine, provided, however, that dust is removed from the sanded surface. However, it is not that simple, as it would seem. A brush or a cloth will not remove fine dust. In addition, fibers can fall out of the cloth, which increase roughness. Fibers 2-10 mm long, even very thin, cause an increase in roughness and surprise the contractor, the bigger, that he was observing all the rules of purity. Dust is best removed with well-treated deer or other wild animal skin, which should be shaken out from time to time. And finally, some practical advice. In order to obtain a surface completely free of dust traces, the last "wipe" should be performed… with your hand, thoroughly washed with soap. It is not a purely technical method, but very effective.

    Before applying the last layer of varnish, which, of course, we will no longer grind, it is necessary to strain the varnish, preferably through a piece of undamaged women's stocking.

    We will now discuss some, selected painting products for wood, their property, application and methods of application. Due to the general tendency to preserve the natural appearance of wood, carpets will be limited mainly to the most common non-pigmented products., mostly varnishes. Varnishes provide colorless coatings, transparent, or translucent.

    General purpose nitrocellulose varnish is used for varnishing furniture and other wooden products not exposed to weather conditions. It can be applied by brush or spray on surfaces not primed or primed with varnish, bone glue solution, pore filler or impregnation. General purpose nitro thinner is used for dilution. The varnish is produced in two forms giving gloss and matt coatings.

    Colorless Capon nitrocellulose varnish has a unique property. It does not change the natural color of the wood. It is used as a protective layer under other cellulose and chemically hardened varnishes. Commonly used for finishing floors made of stave and mosaic tiles. The method of application and dilution is similar to that of general purpose varnish.

    Colorless nitrocellulose primer varnish contains components that protect the wood against the effects of solar radiation and against penetration of resinous substances of coniferous wood into the topcoat. Varnish fills the pores, it is easy to sand and serves as a base for chemosetting and cellulose urethane varnishes. When used under chemosetting varnishes, a hardener for urethane cellulose products is added to it in the amount of 88,5 cm³ on 1 dm³ of varnish. The varnish can be applied by brush or spray after diluting it with a special thinner for cellulose light-protective products.. The varnish is especially recommended as a primer for protective coatings of softwood coverings outdoors.

    Chemosil gloss chemically curing varnishes and Chematosil semi-matte varnishes are two-component. They give hard coatings, good grip, elastic, water resistant, alcohol, fats and temperature fluctuations. A working mixture is obtained, adding to 1 dm³ of varnish 0,044 dm³ of Utosil hardener. Varnishes are applied by brush or spray after diluting with a thinner for chemically hardened products for general use. 2-3 layers are applied on the ground surface and covered with nitrocellulose lacquers (caponowy, general use). The drying of individual coatings takes 4-6 hours, while final drying 24 h. Chemosil and Chematosil are used for varnishing floors, paneling, furniture etc..

    Uretolux synthetic urethane varnishes, Aurasil and Auratosil give flexible coatings, good grip, water and moisture resistant. The varnishes are applied by brush or spray after diluting to the working viscosity with varnish gasoline. The drying time of urethane varnishes is quite long and is quite long 24 h, and final drying - 48 h.

    For wood indoors, dry, a base of nitrocellulose varnishes is used under the varnish; while to summer houses, outdoor carpets, priming is done with varnish diluted with gasoline for varnishes 1:1. A sufficiently thick layer is obtained after 4 or 5 varnishing times. Uretolux gives glossy coatings, Aurasil - semi-matte and Auratosil - matte.

    Fast-drying urethane cellulose varnishes are two-component products. The varnish is mixed with the hardener in the ratio 10:1 immediately before use. They provide flexible coatings, resistant to water and many chemicals. They are applied with a brush or spray on surfaces primed with a nitrocellulose primer for grinding or a light-insulating primer.. These varnishes are made to varying degrees of matting.

    Of the pigmented paints for wood, the most common are general purpose cellulose primers and enamels under the trade names Nitrolite and Nitromal. They are produced in many shades and colors. They give smooth coatings, elastic, adhesive and resistant to moisture. Nitrolite is used for the first painting of wooden surfaces under nitrocellulose enamels. Nitromal is applied to the substrate primed with Nitrolite (it should not be applied directly to wood). Both products are applied in 1-2 layers with a brush or spray after diluting them with a general purpose nitro thinner..

    General purpose polyurethane enamels for wood are two-component. Both components are mixed for half an hour before use in a ratio: 73 g of component A z 27 g of component B. The enamel is applied with a brush or spray after diluting it with a thinner for polyurethane products, directly onto sanded wood. To increase the durability of the coating, the wood can be primed with polyurethane boat varnish. Polyurethane enamels give hard coatings, elastic, grippy, with a high gloss and exceptional weather resistance. They are used to paint floating equipment, garden furniture, bottom itp.


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