The rigorousness of the manufacturing process for stainless steel manhole covers often leads to unforeseen issues during production. This article mainly analyzes the phenomenon of white spots appearing during the manufacturing process of stainless steel manhole covers, and provides the following cause analysis and solutions:

1. The color paste itself was not properly prepared, resulting in floating colors that form white spots on the glass-fiber reinforced plastic (GRP) cover plate.

2. High viscosity of the material paste is不利于dispersion and mixing.

3. Resins with shorter curing times are more prone to the white spotting phenomenon on glass fiber reinforced plastic (GFRP) cover panels, where fibers are not adequately impregnated.

4. Excessive feed rate, the resin has been drained out, causing white spots on the fiberglass.

Issue 5: The dispersion problem of glass fiber and powdered filler can also easily cause white spots on the glass-fiber reinforced plastic manhole covers.

6. The glass steel white spots were caused by inappropriate mechanical forces, resulting in local separation of the resin and glass fibers.