The hardener for pu paints is highly reactive and sensitive to water. No water in the paint, no alcohol solvent, and the moisture content on the substrate should not be too high, it should be left to stand for 15-20min after modulation. Using the wrong curing agent or the wrong amount can lead to dramatic changes in properties. At the same time, too much can not be formulated at one time, and it is easy to gel after a long time. The drying speed is greatly affected by temperature, and it takes about three weeks to completely dry at 25 degrees. The shelf life is short. After opening, the curing agent should be tightly sealed and used up as soon as possible. After it is fully cured, the adhesion of pu paint will not be good, and it needs to be carefully polished. Do not use physical dry paint as base, thick coating is easy to foam, ordinary type is easy to yellow, and non-yellowing type is expensive.