Question 1: One-component polyurethane bulges or the base layer falls off?
Reason: Moisture or volatile solvents in the base layer will cause swelling during volatilization, and floating dust or sand on the surface of the base layer will cause the coating to fall off.
Solution: Make sure that the base layer is dry and free of greasy dirt before applying the polyurethane coating. For example, if there is floating slurry or floating ash on the surface of the base layer, use a wire brush to polish the floating slurry and blow off the floating ash with a blower.
Question 2: Skinning occurs after the polyurethane barrel is opened?
Reason: The packaging barrel is deformed or damaged, which causes a chemical reaction between the material in the barrel and the moisture in the air, which causes the surface of the material to be skinned. After the polyurethane package is opened, the material needs to be used up within 1 hour. If the exposure time is too long, the surface will be skinned.
Solution: After the surface of the material in the polyurethane barrel is skinned, remove the surface skinning. As long as the lower coating is not cured, it can continue to be used.
Question 3. The surface of polyurethane coating film is rough and cracked?
Reason: After the polyurethane coating film is painted, the interface agent is used to pull the hair after the coating is not completely cured. The polyurethane coating film has not fully reacted, and there is still solvent oil attached to the surface. At this time, the drawing will cause cracking and hollowing.
Solution: After the coating film is completely dry, the interface agent on the surface of the coating film is completely polished off and the surface is cracked and hollowed, and the roughing treatment is performed again.
Gift: How to solve the problem of high viscosity of polyurethane?
Polyurethane is a one-component solvent-based coating with high viscosity and difficult construction. It is recommended to use scraper coating instead of rolling or brushing. In addition, a thinner can be added to the coating, and a test must be done before use, with a small amount of sample brushing, to check the film formation effect and quality of the coating, and then use it in large quantities after passing the test.