The performance inspection of paint construction parts is divided into hiding power, usage amount, brushability, leveling performance, drying property, thickness and sanding property, etc.
1. Determination of hiding power
The measurement of paint hiding power (testing instrument: hiding power paper) should be measured according to GB1726-79 "Determination of Paint Hiding Power". That is to say, the minimum amount of paint that is evenly applied on the surface of the object so that the base color no longer appears, expressed in g/㎡.
(1) The black and white grid glass plate can be made by brushing and spraying.
When painting by brushing, use a 100m x 250mm glass plate (thickness 1.2~2mm), cover one end with 100mm x 50mm (reserved for hand-holding during testing), and then paint on the remaining 100mm x 25mm area Spray a coat of black nitro paint on it. After drying, use a knife to carefully cut off a square of 25 mm x 25 m at intervals, then soak the glass plate in water for a while, take it out to dry, peel off the square paint film at intervals, and then spray a layer of white nitro paint to make it dry. It becomes a glass plate with 32 square black and white intervals, and then sticks a piece of smooth kraft paper, scrapes and coats a layer of epoxy glue to prevent the solvent from infiltrating and destroying the black and white grid paint, and then it is made into a strong black and white grid board.
When spraying, you can spray a layer of black nitro paint on a 100 mm x 100 mm wooden board. After it dries, stick a piece of white thick smooth paper of the same size on the paint surface, and then use a knife to carefully scratch off 25 mm at intervals. The square of X25 millimeter, spray one deck of white nitro lacquer again, carefully peel off the remaining spacer square paper after drying, promptly make the black-and-white spacer plate with 16 squares.
(2) Measuring method There are two methods: brushing measurement and spraying original measurement.
When brushing is measured, according to the viscosity specified in the product standard (testing instrument: viscometer), the total weight of the cup containing the paint and the paint brush can be weighed on a balance with a sensitivity of 0.01g or 0.001g. Use a paintbrush to paint evenly on the black and white poles of the glass. After each painting, put it in the dark box, 15 to 20 cm away from the frosted glass. Observations under 1 and 2 fluorescent lamps all end with the black and white grid just invisible. Then weigh the cup and paintbrush containing the remaining paint to find the weight of the paint on the black and white squares. The paint should be painted quickly and evenly, and the paint should not be brushed on the edge of the board. Calculate hiding powerX (g/㎡) is calculated by the following formula with wet paint film:
2. Determination of usage
The amount of paint used can be measured according to GB1758-79 "Measurement of Paint Usage Amount", that is, the amount of paint required to form a paint film of a certain thickness on the base plate per unit area, expressed in g/㎡.
3. Determination of drying time of paint film
The determination of the drying time of paint desert can be determined according to GB1784-79 "Determination of drying time of paint film putty". Under the specified drying conditions, the time for the paint film to reach the surface dry is the surface dry time (testing instrument: drying time Tester), and the time for the paint film to completely dry is the actual drying time. Expressed in microns.
4. Determination of coating abrasiveness
It mainly refers to the determination of primer and putty sandability. The determination method can be determined according to GB1750-79 "Determination of the Abrasiveness of Primer and Putty". Generally, a grindability Tester is used, and after a certain number of grinds, the surface phenomenon of the coating is evaluated.
