Wood surface common surface treatment technology
Whether the surface of the coated wood product is smooth and clean, whether there are defects such as stains, glue marks and resins, has a direct influence on the quality of the coating. For this reason, it is necessary to carry out various necessary treatments on the coated surface before painting to paint the paint. Wood surface treatment. 2. It mainly includes the technique of removing resin, removing wood wool, embedding holes and cracks .
CN" face="宋体" size="3">(-) to resin
Many woods contain resin and the surface is greasy, which seriously affects wood dyeing and reduces coating adhesion. To this end, the resin on the surface of the wood should be cleaned with other oil traces. The following methods are commonly used to remove the resin: 1
. If the content of the resin is small, the resin can be scrubbed off with hot soapy water, and then rinsed with water; 2
. If the content of the resin is large, it is necessary to react with the resin with an alkali solution to form a soluble soap, and then scrub with a yarn to remove the water, which is easy to remove. A commonly used alkaline solution is an aqueous solution of 6 to 10 % sodium carbonate and an aqueous solution of 4 to 5 % caustic soda. The resin is more, and the concentration of the alkali solution is correspondingly increased. Under the action of the alkali solution, the surface of the white blank of the wood product will be darkened, mainly to become light yellow. Therefore, for wood products that require light coloring, it is advisable to use a slightly thicker soapy water to remove the trees. (
b ) Decolorization If there are natural spots on the surface of wood products, or if they are contaminated by other pigments, which will affect the uniform coordination of the color of the finish, local decolorization is required to remove stains or stains. If the product needs to be painted in light or white, and the color of the wood itself is different, or the color of the whole surface is dark, then the surface of the wood should be completely bleached. Common methods for decolorizing wood surfaces are: 1
. After mixing with a 30 to 35 % aqueous solution of hydrogen peroxide and a 28 % aqueous ammonia solution at a uniform ratio of 1 : 1 , the mixed solution is applied to the stain or the stain with a paint brush, and the stains and stains are generally eliminated by themselves. The method has good decolorization effect, and can be applied once without washing with water. However, there is an ammonia odor, and the prepared mixed solution (decolorizer) is only valid for about 30 minutes. For this purpose, the two solutions can be separately applied to the surface of the wood to decolorize, and a better decolorization effect can be obtained. 2
. Rub the surface of the wood with a concentration of 30 ~ 35 % sodium hydroxide solution; about 10 minutes, then apply 30 % hydrogen peroxide, let it fully react to remove the pigment, then scrub with water; then use a concentration of 1 . 2 % acetic acid or oxalic acid aqueous solution is neutralized; finally, it is wiped clean with water to make it fully dry. This method has a remarkable effect on the decolorization of wood such as ash, eucalyptus and the like. 3
. At a concentration of hot aqueous 5% sodium hypochlorite was added trace (about 1 sodium hypochlorite solution - 2%) sulfuric acid or oxalic acid Stir coated bleaching, the color will itself off. This method is more effective in eliminating pigmentation of switchgrass wood. 4
. Remove iron contamination available pigment concentration of about 5% oxalic acid solution with a concentration of approximately 5% hydrogen peroxide solution was mixed PH value of about 8, applied to pollution, the reaction was allowed to return dye. Then scrub with clean water. 5
. Remove acid-contaminated pigments (generally light red) and treat them with hydrogen peroxide at a pH of 8 to 9 and a concentration of 2 to 10 %. Start treatment with hydrogen peroxide at a concentration of about 2 %. If the depigmentation effect is not obvious, increase the concentration of hydrogen peroxide until the pigment completely disappears. 6
. Removing the contaminated base pigment (typically brown), available PH value of 5-7, at a concentration of 5 to 10% hydrogen peroxide solution, the PH value of the treated water may be 7, if the effect is not obvious to color, can be transferred to 5, Gradually increase the acidity of hydrogen peroxide. (3) In addition to wood wool The surface of the wood has undergone various cutting processes. Although it has a certain degree of finish, since the wood is made of fibers, there is always a certain soft wood wool attached to the surface of the wood regardless of the type of fine or fine sand. Once the liquid coating is applied to the surface of the wood, the wood wool is swelled and hardened and erected, and the surface of the originally smooth wood becomes rough. This will affect the uniformity of wood dyeing, because the dye solution will accumulate at the base of the wood wool, forming a "sesame"-like white spot, commonly known as "sesame white"; at the same time, it will also reduce the adhesion of the film. To this end, the wood wool on the surface of the surface must be removed before painting. The following methods are commonly used to remove wood wool: 1
. First, use a yarn or towel to soak in water and then wring it out slightly. Rub the surface of the product along the direction of the wood fiber to make the wood wool swell, then the direction of the transverse fiber means that the wood hair is erected. After the wood wool has dried and hardened, sand it with the No. 1 wood sandpaper along the fiber direction. Otherwise, the wood fiber will be cut. The more sand the wood wool, the more the horizontal marks, and the texture of the wood surface will be seriously damaged. Although it is economical to eliminate the wood wool by this method, the surface of the wood is slow to dry, and the wood wool is not hard enough to be sanded, so the application is less. 2
. The surface of the product is applied to the surface of the product with a concentration of about 5 % of the bone glue or the skin glue. The wood wool is swelled and the hardness is also large. The wood wool is removed by the No. 1 wood sandpaper along the fiber direction. The effect is better. 3
. The surface of the article is painted with a shellac varnish at a concentration of approximately 15 %. When the wood wool encounters the worm varnish, it will immediately swell and erect, quickly dry and harden, and it is easy to remove the sand along the direction of the wood fiber by sandpaper. This method is reliable and widely used. 4
. Apply 5 ~ 8 % polyurethane varnish or other varnish to the surface of the product. The wood wool will also swell and harden. After it is fully dried, it will be completely removed by sandpaper. While sanding the wood wool, the smudges on the surface of the product should also be completely removed. For sandpaper that removes wood wool , wood sandpaper of No. 0 or No. 1 is generally used . Because the sandpaper is too thick, it will affect the improvement of the surface finish of the wood; the consumption of fine sandpaper is high and the sanding efficiency is low. (4) Surface inlay In addition to the natural defects of wood in the surface of wood products, defects such as cracks, nail holes and ribs may occur during the production process. The presence of these defects will affect the quality of the finished product and must be repaired. In the finishing process, a variety of Xu material and body pigments and coloring pigments are used to adjust the thick putty to put the patch. Due to the different coatings used, the putty can be divided into oily, nitro, phenolic, alkyd, raw lacquer, shellac and other types. Among them, the shellac putty has the characteristics of quick drying and easy sanding, and it can be used in wood furniture finishing regardless of whether the product can be inlaid before or after coloring. Since the shellac putty dries quickly, it needs to be used while blending. When mixing, pay attention to the color of the putty should be slightly lighter than the color to be painted. If the product is painted in mahogany color, the putty should be painted in light red wood. Because when the product is colored in the subsequent process, the putty embedded on the product will also absorb the color, so that the color of the product is consistent with the color of the product being coated, and secondly, the prepared putty putty will be used in the process. Gradually become hard, not easy to fill, can increase the amount of shellac varnish or alcohol, re-adjust to a thick paste, can continue to use. Otherwise, it will reduce the adhesion of the putty. Because oily, phenolic, and alkyd putty are slower to dry, they are less used alone in the embedding of caves and cracks. They are mainly used for grain filling holes in wood products, and holes and cracks in wood products are also filled while filling holes. Filled in together. That is to say, for products using oily, phenolic, alkyd and other putty-filled holes, there is no need to embed the hole clothing and cracks. Nitro putty is mainly used for repairing nitrocellulose lacquer. Because of its high cost, it is rarely used in large quantities. Raw paint putty is specially used for the surface embedding and filling holes of painted lacquer products. The surface of the woodwork is now hand-operated. Before the inlay, the dust, wood chips, etc. in the depressions, holes, and cracks should be removed to avoid reducing the adhesion of the putty. Then use the inlay knife to flatten the subtractor and press it tightly inward to fill it. The embedded putty layer should be controlled as far as possible in the depression, and should not be enlarged to the surrounding wood surface, but the embedded putty layer should be slightly higher than the surrounding wood surface, so that the putty layer can be sanded after sanding. A consistent flatness of the wood surface. After the surface of the wood product is treated by the above-mentioned process technology, a smooth flatness, a small color difference, and no resin oil trace are obtained, and the coating paint can be applied.
Pharmacy Essential Oil
Seabuckthorn Seed Oil,Pomelo Peel Oil,Carrot Seed Oil,Pharmacy Essential Oil
Ji'An ZhongXiang Natural Plants Co.,Ltd. , https://www.zxessentialoil.com