The following several methods are applicable to the preparation of various paint films on any kind of surface with different paint materials. Before the paint material is painted, the surface treatment must be carried out professionally and the paint material to be tested must be prepared.
surface treatment
1. Use No. 280 and No. 360 emery paper to remove the iron rust and oxide skin on the surface of the black iron plate (90x120 mm, 70x150 mm or other sizes), and then use a dry cloth with gasoline or wine wipe
2) Wipe the surface of the hard aluminum plate (90x120 mm, 150x250 mm or other rulers) with a clean cloth purchased with B-70 aviation gasoline, and then dry it with buckskin or mechanical cloth.
3 Clean the surface of the board (plywood) (70x150 mm, 150x250 mm or other R inches) carefully with glass sandpaper, and then wipe it with a brush,
4 Wash the surface of the broken glass plate with hot soapy water, then dry it with a clean cloth or let it dry in the air. Before painting, the test plate should be marked clean with a rag containing gasoline, alcohol or other solvents.
Preparation of paint materials All paint materials (cooked oil, varnish) that do not contain pigments must be filtered through wire knots before being removed. The film formed on the surface of varnish hot oil should be removed in advance. All paint materials (color paint, enamel paint) containing pigments must be carefully stirred and passed through a copper sieve with no less than 2400 holes per cm2 before finishing. After fishing, the film formed on the surface of the paint should be cut and removed in advance.
With different technical conditions, the paint material must be diluted to the required viscosity with a suitable solvent before finishing. ; on nitric acid vinyl varnishes and paints, use PIIB solvent; on vinyl peroxide varnishes and paints, use P-4 solvent; Methyl; in the varnish and paint of modified phenolic resin, use dimethylformaldehyde and solvent naphtha; in organic cinnamon varnish, use benzene and xylene. (Related instrument: viscometer)
When coating the paint material on the surface, it is necessary to prepare a paint film with a certain thickness according to the pre-calculated material quantity or according to the specified material consumption quota. With the different paint materials used and test conditions, the paint materials can be used in different ways. The method is to remove on the surface, and the brushing method is to dip the brush in the sample first, and then squeeze it gently. Then brush the paint material on several parts of the painted surface. Then quickly distribute the sample into a uniform thin layer in the horizontal direction of the paper, but there must be no blank space between the brushes, or Can not form a sagging state. (Related instruments: Sag Tester)
After removing the oil-based paint with a brush, use a flat brush to level it out.
The spraying method is to spray the paint material on the surface repeatedly, first spray horizontally line by line, and then spray line by line level, but there should be no gaps between the lines, in order to get a uniform paint layer, the paint sprayer A certain distance (150-200 mm) must be maintained from the de-decorated surface and the paint sprayer must have a constant movement speed (8-10 cm/s) along the surface.
In order to meet the requirements of the laboratory test, it is recommended to use a KP-10 or KP-30 paint Spray Gun (buy at Shenlan 184), with a working pressure of 3.5 atmospheres and a nozzle diameter of 1.8 mm.
Dip the test panel into the paint material, take it out after a few seconds and place it at a 45 angle for 10-20 minutes, when the excess sample flows down from the panel and the first layer thus dipped has dried, Submerge the other end of the test plate into the sample again, take it out after a few seconds, and place it at an angle of 45° for 10 to 20 minutes. Thereafter, follow the regulations of the technical conditions to make the coating film dry. (Related instrument: drying time Tester)
In order to obtain a uniform paint layer with a certain thickness, a special automatic device that can guarantee a certain speed must be used. This device is described below. (Related instrument: Coating Thickness Gauge)
Pour the paint material on the test board and set the test board at an angle of 45° for about 10~20 minutes, so that the excess sample can flow down from the board. Very horizontal surface), a uniform paint film can be obtained.
When the first layer is dry, pour the paint material from the other end on the test panel to form a second layer, and then follow the above method.
Scrape coating In order to use a scraper to apply the putty into a uniform layer with a certain thickness, a special construction frame and a carved board can be used. The scrape coating method is described in the following.
