1. Not dried thoroughly
The coating film is not completely dry after drying (self-drying or drying), and the coating film feels wet when touched by hand, the coating film is soft, does not reach the specified hardness, or is dry on the surface and not dry on the inside.
1) The temperature and time of self-drying or drying did not meet the process specifications.
2) The self-drying place has poor ventilation, high humidity, and low temperature; the technical state of the drying room is poor. 3) The temperature is low or the drying time is insufficient.
4) The paint is applied too thick at one time (especially the oxidation-cured paint).
5) The desiccant contained in the self-drying paint is invalid, or the amount of the surface-drying desiccant is too much.
6) There are too many objects to be dried in the drying chamber, and workpieces with different heat capacities are dried in one drying chamber at the same time.
7) There is wax, silicone oil, oil and water on the object to be coated.
1) Strictly implement the drying process specifications.
2) The technical status of the self-drying place and drying room should meet the process requirements.
3) Oxidation-cured paint should not be applied too thick at one time (relevant instrument: paint Film Thickness Gauge) , if the thickness exceeds 20 microns, it should be applied several times.
4) Add desiccant and adjust the amount of surface-drying desiccant.
5) Workpieces with different heat capacities should have different drying specifications (or the drying time should be calculated after the workpiece reaches the drying temperature) (related instrument: drying time Tester) , and the loading capacity of the drying chamber should be controlled within a certain range .
6) Strictly prevent oil, wax, water, etc. from the coated object and compressed air from being brought into the coating.
During the drying process, due to the high drying temperature or too long drying time, the coating will lose gloss, change color, become brittle, crack and peel off.
1) The drying equipment is out of control, causing the drying temperature to be too high.
2) The drying time is too long, such as on the assembly line, the coated object stays in the drying room or overnight, especially in the case of drying above %"&, it is easy to cause over-drying phenomenon.
3) Improper selection of coating matching and drying specifications.
1) Ensure that the drying equipment is in good technical condition to prevent the drying temperature from getting out of control.
2) The drying time should comply with the process regulations. If the object to be coated stays in the drying room for too long for some reason, try to cool down urgently. In the case of high temperature drying, the object to be coated should not be placed in the drying room overnight.
3) Coating matching should be appropriate, and the drying temperature of the top coat should not be higher than that of the base coat.
The coating film is not completely dry after drying according to the process specifications, the coating film feels wet to the touch, the coating film is soft and does not reach the specified hardness, or there are phenomena such as surface dryness and inner dryness, and small skin-like "wrinkles" are formed on the surface.
1) The mixing ratio of the two-component paint is incorrect.
2) The self-drying place has poor ventilation, high humidity and low temperature.
3) Excessive use of slow volatile solvents. The thinner used when spraying two-component polyurethane coatings contains water, acid, alcohol or acid.
4) The paint is applied too thick at one time (especially the oxidation-cured paint). The desiccant contained in the self-drying paint is invalid, or the amount of surface-drying desiccant is too much.
5) There is wax, silicone oil, oil, water, etc. on the object to be coated.
1) It is necessary to adjust the proportion of two-component coatings strictly according to the manufacturer's requirements, and prevent the curing agent from becoming invalid after long-term storage.
2) In the paint with working viscosity, the amount of slow volatile solvent should not exceed " #.
3) Check and adjust the environmental conditions of the self-drying place and the technical status of the drying room to meet the conditions required by the process.
4) The self-drying (oxidative curing) coating should not be applied too thickly at one time, if the thickness exceeds $%&&, it should be applied several times. If it is caused by desiccant failure, add desiccant, and pay attention to the amount of surface drying desiccant.
5) Strictly prevent oil, wax, water, etc. from being coated and compressed air into the coating.
'Two-component paint should use the manufacturer's matching thinner.
1) If the drying process specification can be changed, change the drying specification to remedy it.
2) If the above method cannot be remedied (still not dry, or dry on the outside), or not dry due to oil pollution, it should be rubbed off or removed, and repainted.
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