Covering problem - sagging, bubbling

Before and after coating the gloss film, various defects often occur on the surface of the coating due to factors such as storage, preparation, and operation. The following are several common faults of coating gloss coatings.

. Flow hanging

Flow hanging, also known as oil flow, often occurs on the vertical surface of the workpiece and at the corners of the line grooves. The coating flows down, causing uneven thickness of the coating film, similar to tearing or sagging of the curtain, which is a common defect.

① When constructing on vertical surfaces, do not apply too thick a coating at once. When brushing, do not dip the brush too much in paint; The nozzle diameter of the spray gun should not be too large during spraying; When dipping, it is even more important to pay attention to draining the paint attached to the workpiece. If possible, a spin dryer can be used to shake off excess paint.

② When the operating environment temperature is high or the viscosity of the coating is low and the solvent evaporates quickly, it is also easy to form sagging. Therefore, the operating environment temperature should be between 20-25 ℃, and the solvent evaporation rate should also be moderate.

Bubbling

The reason for foaming is mostly due to incorrect operation, and it should be corrected according to the cause.

① The workpiece has moisture and is coated with a gloss film before drying. During the drying of the paint film, the moisture evaporates and breaks through the gloss film, causing bubbles.

② The workpiece has many pores, and there is a small amount of air left in the pores. When drying, the expansion of air can also break the mask.

③ Immediately place the newly coated gloss film into a high-temperature oven (or near a high heat source), as the surface dries too quickly and the diluent inside continues to evaporate, lifting the gloss film.

④ During operation, it is exposed to direct sunlight and the local temperature is too high.