The wood grain for screen printing is a technology transplanted from fabric printing and dyeing for the simulation of native materials. The same wood grain can be printed in batches after being made into a silk screen mold, which has a strong sense of reality and a high production rate, but it is only suitable for printing on a flat surface. At present, it has been applied in some furniture factories. Of course, in addition to simulating wood grain, it can also be used to simulate other patterns and print various patterns.
The original pattern printed on the furniture is obtained by scraping and flowing the pigment and color strands through many small holes arranged in the wood grain on the screen printing screen. The key of screen printing is to adjust the screen back plate, and its royal process includes royal wood grain negative film, nylon screen wooden frame, blending and brushing photosensitive liquid, flashing and washing, brushing hardener, etc. also
The formulation of printing inks is also important.
(1) Production of wood grain screen
① First, according to the size of the printing area, make a wooden frame, and flow several polyvinyl alcohol shrinkage glue on the bottom edge of the frame, and then stick a layer of 130~170 mesh nylon screen, and stretch it tightly.
②Make wood grain negative film: use photographic method to thin the simulated wood grain object or sample core into a negative film equal to the printing surface. You can also spread the polyester transparent film or tracing paper on the sample board, and draw the wood grain by hand with drawing ink. If you want to show the depth and level of the printed wood grain color, you need to make 2~4 color separation negatives. At this time, a few more pieces of nylon netting should be made correspondingly.
④ Preparation of Biguang Liquid. Now introduce two preparation methods:
a. Dissolve the polyglycol solution in Table B in water, add 20 parts of water for every 1 part of polyglycol solution, let it stand for several hours, boil it in water for 4-5 hours, and then cool it down. Add nitrogen water and adjust the pH according to the climate. If the air temperature is above 2s°C, add nitrogen water to the pH of the liquid to make it 9~10. If it is below 25°C and the humidity is high, adjust the pH value to 7~9. After the glue is adjusted, add citric acid, 0.5 grams per 100 grams of glue. The subsequent operation process needs to be carried out during the operation, so as not to feel the adjusted glue. Add 2 grams of ammonium dichromate per 100 grams of glue. Filter the glue solution with a nylon mesh for use.
b. Dissolve 1 part of gelatin in 7 parts of water, boil for 2 hours after 1 hour, cool to about 50°C, add ammonia water to adjust the pH value, if the temperature is high and the weather is dry, adjust the pH value to 8~9 ;When the temperature is low and the humidity is high, the pH value is adjusted to 7~8. Then add 28 grams of dichromic acid per 100 grams of glue to make photosensitive glue, filter and set aside. ④ Coating photosensitive glue on the screen: In the darkroom, brush the photosensitive glue on the stretched nylon mesh with a wool pen, then use a plexiglass scraper to scrape off the excess glue from the front and back of the screen, and place it at 35°C Dry in an oven to form a photosensitive film.
⑤Exposure: In the dark room, press the wood grain negative film or the transparent film painted with wood grain on the nylon mesh film, and then paste it on the glass surface of the photosensitive box. Cover the other side of the nylon net with black paper, pad with felt, sea tuck, and wooden boards and clamp them tightly so that the wood grain negative film and the photosensitive film are tightly spaced to prevent light leakage. Remove the black cloth in the sun, and turn the glass plate to the sun. Expose for 15-20 seconds under strong light, and 25-40 seconds under low light. After exposure, immediately board the black cloth and send it back to the darkroom for processing.
⑥Flushing: Rinse the nylon net and silk screen with warm water in the dark room. After the water is finished, it can be operated under bright light to remove the non-photosensitive adhesive film, that is, to form a mesh with a wood grain pattern distribution in the non-photosensitive part to achieve smooth flow. until water seeps through.
⑦Brush and hardener: After the nylon screen plate is dry, brush a layer of hardener on the front of the photosensitive liquid to protect the photosensitive film and make it firm and durable. The hardener is made by stirring 10 ml of formaldehyde, 5 grams of potassium dichromate, 5 grams of potassium alum and 360 ml of clear water. After the hardener is applied on the front side, the mixed solution that seeps into the back side should be wiped off immediately on the back side of the nylon screen with a yarn head until all the wood grain screen holes are unblocked.
(2) Printing of screen wood grain
The process of making the base of the furniture printing surface and printing the wood grain is the same as the process of manually simulating the wood grain of Ash. Printing inks can be made from laver gum (or asparagus gum) mixed with pigments, ink, etc. First boil laver gum with water (laver gum: water = 1:19), and then add iron red, ink and other pigments after it is completely dissolved. The specific color matching should be based on the simulated wood grain. When printing, put the wooden frame screen on the surface of the furniture to be printed, add ink to the nylon mesh, and scrape back and forth with a scraper for 1-2 times, so that the furniture surface can obtain the required wood count. If you want to print the depth and level of the wood grain color, you need to overprint more than 2 times. The overprinting must be accurate, and the oil color used each time must be registered to get a realistic wood grain.
