Technical points of American antique furniture painting process
American painting refers to the use of furniture paints suitable for use in Europe and the United States. American furniture is influenced by the historical background, culture, art and living habits of Europe and the United States, with a strong European and American style. The painting characteristics reflect the psychological needs of retro and return to nature. The paint used in painting is almost all of the nitrocellulose (NC) series, so it is a trend in the development of furniture painting. An excellent product not only requires strict quality control, but also requires strict production procedures. Therefore, the coating process technology and the coating and coating substrate are the three major factors that determine the quality of the coating. This paper analyzes and elaborates the American painting process technology for reference in teaching, research and production.
First, the wood pre-treatment
Substrate processing is the first step in the success of painting and is a necessary condition for completing a good product. Therefore, the quality of the surface treatment is related to the quality of the coating and the finished product. There are several items in the pre-painting process:
1) Bleaching
Because the wood is different from the sapwood, the color of the wood is different. In order to make the color uniform, especially the light color product must be bleached. The purpose is to make the uneven color change from deep to light and the color difference is small. At present, the most effective wood bleaching method is hydrogen peroxide (commonly known as hydrogen peroxide), and the catalyst must be added to produce bleaching effect. The most commonly used catalyst is ammonia. The method of use is as follows:
a. Using 10-20 parts of hydrogen peroxide (concentration 30-35%), mix a portion of ammonia water (concentration 23-25%) and brush the surface of the wood. If the bleaching power is reduced by water, alcohol can also be used. The difference between the two is mainly due to the different effects on the swelling property of the wood.
b. After bleaching, stop at room temperature for 1-2 minutes, then heat-bake at 45-55 ° C for 10 minutes or dry at room temperature for 30 minutes; bleach can be repeated once, can not be reused;
c. After drying, the surface is washed with water, completely dried at room temperature or dried at 50 ° C for 90 minutes; then sanded.
2) Fill
The finished finished filler (commonly known as putty and soil) is used to fill large natural defects such as insects, cracks, etc. If the thinner is added with thinner, the thicker can be added with filler, the effect is to increase the sand. Grinding properties and keeping the material smooth. It must be dried for more than 1 hour. Note that the filler used at this time is a thick material, and some books are called embedding or substrate finishing.
3) Sanding
Usually sanding with coarse sandpaper (80#-100#), sanding with fine sandpaper (150#-180#) or directly with 240# sanding. The most commonly used sanding machines are automatic sanding machines or belt sanding machines. The flat parts are directly air-conditioned wide-width sanding machines, which can be used for 5-10 filaments. Pay attention to the sanding to the smooth and clean wood, not too fine grinding, the last machine sanding should use 240# sandpaper, preferably before the painting is on the line.
4) Damage handling
In order to imitate the phenomenon that some products become damaged and old after being used for a long time, it is necessary to do the damage treatment after the last white body sanding, that is, to use the different destruction tools to make the old appearance of the antique effect, the main methods are as follows:
a. coarse sandpaper is coarsely ground on the corner of the table and above the table legs, and a sickle is used to draw a scar on the edge of the table to achieve the effect of natural wear;
b. Use iron chains to slap on the edge of the furniture to create traces of natural damage, and use a pointed hammer, screw cap and bolts to make a slight tap on the surface of the furniture to create a dent;
c. Use a carving knife to draw a scratch-like effect;
d. If the surface of the wood is hit with nails or screws, it can form a pest-like effect.
After this process is finished, it must be sanded, otherwise it will directly affect the coating effect.
Second, the wood coating process
1) Material adjustment
Use an equalizer (commonly known as green water) or white edge paint (commonly known as red water, color modifier) ​​to adjust the material according to the color of the swatch, in order to further eliminate the chromatic aberration. It should be noted that only one of them is generally used, and the material should be bleached to obtain the desired effect.
2) overall coloring
Also known as bottom coloring or material coloring, the color of the base color is further brought to the color of the color plate by using a suitable coloring agent, and the coloring agent, the scent, the dulo coloring agent and the oil coloring agent can be selected according to the substrate and the product. Generally, the spraying method is adopted, and all are uniformly sprayed.
In this process, the infiltration color is generally used in the factory. It is not allowed to add a large proportion of color paste. Otherwise, it will not be able to level well, and the uneven penetration will not be achieved. Some of the color unevenness in the transparent coating is often caused by the process.
3) First primer
Also known as a glue primer, the solid content is usually between 4 and 14%. Because of its low viscosity, it can penetrate into the surface layer of wood quickly, which can seal the base color. Second, it can provide the "extension" effect of the subsequent process of painting. .
In general production, the viscosity is usually 8~12s, and the solid content is 8%~12%. Another important effect after spraying is to cause the wood fiber to run up again. After light sanding, the primer can be applied to obtain clear color. The improper handling of this process or the way to polish it will affect the clarity of the color.
4) Grice colorant
Also known as antique lacquer or antique oil, it is a slow-drying and easy-to-wipe oil or resin with a good transparency of pigment dispersant, made with slow drying solvent. Its role is to create a soft taste and shadow effect by wiping the surface to create a classic taste. Because it is a slow-drying oily coloring agent, it does not dissolve the underlying top primer and the upper second-degree primer, so it is also used by keeping a little effect.
When making antique oil, if the material conduit is larger and deeper, in order to obtain better coating film, smoothness and save paint consumption, a small amount of filler should be added in the production, containing a small amount of resin and body pigment, and evenly stirred. The effect is better.
5) Do the light and dark
On the upper Douglas coloring agent, use #000 or #0000 steel wool, wipe the direction of the wood grain for light and dark contrast operation, and finally use a brush or rag to draw out the light and dark places, so that the color is soft and natural. Effect. The purpose is to show the stereo effect of the wood and increase the shadow contrast effect.
6) Second primer
Often called SEALERS in production
It is a primer with a solid content of usually in the range of 14 to 25%. It is mostly rapid drying. It is used to protect the underlying colorant and the Grice colorant, and generally contains a sanding agent. The viscosity can be adjusted to 16s depending on the situation. 5 to 15 minutes to sand, and at the same time and the bridging effect of the topcoat.
7) Printing
Also known as repair colorants, generally using alcohol colorants. In some special coating colors, the coating film is printed with a soft cloth to make a bright layer effect, strengthen the wood texture effect and increase the three-dimensional effect.
The operation technique is to use a soft cotton cloth to soak in the alcohol coloring agent, and then wring it a little, then hold the cotton cloth on the surface of the substrate by hand, all or part of the action of tapping, and then use 0000# steel wool to rag the rag. The shape becomes softer and catches the dark.
8) Dry brush
The purpose is to play an antique role, generally using Grice colorants. Partially lacquered, with special effects at the edges, corners, knives, grooves or engravings of the product.
9) oxtail marks
The oxtail mark is generally used to use the Gris coloring agent, and it is lightly smeared with a oxtail pen, often in a lighter place and at the edge.
The operation technique is to use 4 to 5 long centimeters of cotton thread, tape a piece of front centimeter, and then seal the unsealed end of the primer. After drying, a oxtail rope will be formed. Wet the antique oil with a oxtail rope, wipe it with a rag and make some short irregular marks and curves on the board.
10) Fly black spots
"Flies black spots" is a decorative effect that also becomes a spray point. Generally, it is black and brown. It uses alcohol coloring agent or Grice coloring agent. It can use the spray gun to adjust the air supply volume and the oil quantity to spray out. The function is to show the hidden and classical furniture effect.
The main point of operation is to put alcohol and printing coloring agent into the spray gun, and then spray the spot. When spraying, the air pressure of the spray gun should be controlled. Generally, it needs repeated debugging to achieve the effect.
11) Topcoat
After finishing the above-mentioned old process, the top coat is applied to protect the lower layer effect and increase the film thickness, and most of the spray is applied twice.
If you need to apply the grooved paint, it should be done after the first coat of paint, and pay attention to not sanding before applying the grooved paint, which is easy to be wiped after painting; in the general production, the factory is coated with two coats. Wipe the cloth, use the 0000# steel wool in the second lane, and finally clean the corner with a brush. This process is very difficult because most of the grooved paint will dissolve after the topcoat is sprayed, and how much will be retained when the finish is applied, mostly depending on experience.
12) Dust paint
In the old-fashioned or ancient-style painting, in order to make the appearance of the product look old and ancient, it is usually left at the edge, groove or carved of the product. It is operated with special antique oil, which seems to have gathered a lot of dust in the furniture after a long time. The same.
This method is commonly used in the American antique crack paint coating. After the coating, it is wiped clean with steel wool to leave only the groove.
13) Polishing and waxing
First use #800-#1000 water sandpaper dipped with lubricant or loose perfume to smooth the surface of the coarse sand, then use #0000 steel wool polishing, and finally use 2000rpm high-speed polishing machine with a wool wheel polished to the required brightness, with Wipe clean with a clean soft cloth; the purpose is to make the surface of the coating smoother, increase the feel of the film and enhance the appearance of the film.
Third, the typical painting process example
Through the above analysis and examples, we can see that the reason why American painting is popular all over the world is not only because the United States furniture consumption ranks first in the world, but essentially the high level of design process, precise coating process and strict materials. Controlled and cleaned by the coating environment. A high-quality product is a scientific and rigorous coating process. The complex multi-channel decomposition coating process ensures high-quality control of mass production, which is the only way for large-scale furniture painting production. It is worth learning from our domestic furniture companies.
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