Why Silicone Keycaps Show Pits, Rough Laser Marking, and Uneven Spray Coating
A customer recently asked us, “Can you make the spray coating on the sample smoother?” We asked what they meant by smoother. They explained, “The surface can’t have pits or holes, and the laser-etched lettering can’t look rough.” (Chicarubber)
They sent us a mold to run samples. We also asked for their laser-etching artwork and tested it. Even then, we still saw some small pits on the surface. So let’s break down why this happens—and what to control to get a clean, smooth finish.
1. Start with the Mold Surface
Because the keycap surface is a visible exterior surface, the mold itself needs the right surface finish. We use EDM to keep the mold surface flat and uniform—first a rough pass, then a fine pass. This helps prevent pits, bumps, and uneven areas from transferring to the molded part.
A good mold surface is the foundation of a good keycap surface. If the mold is not smooth enough, no amount of spray coating will fully hide the defects.
2. Purge the Mold and Use a Longer Cycle Time
During sampling, run several shots of silicone first to purge dirt and residue from the mold surface. Once the mold is clean, switch to clean silicone material. The key is to use a longer molding cycle time.
A longer cycle helps the silicone fill, cure, and release more cleanly. When the part comes out of the mold with a clean surface, the later spray coating step becomes much more consistent.
3. Control Dust Before Spray Coating
Before spray coating, dust control is essential. When loading parts onto trays, use a static or ionizing gun to blow off the keycap surface. Then move the trays into the spray coating conveyor line.
For the ink, choose a finer ink with good adhesion. A finer ink helps the coating lay down more evenly and keeps the laser-etched graphics from looking rough or grainy.
4. Why These Steps Matter
Pits, craters, and rough markings on silicone keycaps usually come from more than one source. Mold surface quality, mold contamination, cycle time, dust, and ink choice all affect the final appearance.
If you want a smooth, clean, premium-looking surface, every step has to be controlled—from mold EDM to molding, purging, dust removal, and spray coating. (Chicarubber)
Final Thoughts
These are the key points to watch when you want to prevent pits and surface defects on silicone keycaps. The details make the difference.
Looking for silicone keycaps with a clean spray-coated surface and crisp laser-etched legends? Contact us for samples and production support.
Why Silicone Keycaps Show Pits, Rough Laser Marking, and Uneven Spray Coating
If you need to customize silicone products, please contact us at chicarubber
