Hi! I'm currently give support to the coating department for their new 1.6 FSV lenses using the PPG 1.6 coating. We use SCL CD1000 machine.

Lately we found many rejects (we called "blob"). The whole lens is full of this blob and it seems to stick on the surface. I believe that it came from the coating solution because when I check the coating solution, there are lots of coating precipitate. However, we still unable to trace on where it came from.
During production, the first 4 hours it was ok. No rejects at all. But after that this reject appear suddenly. It cost 50% - 70% rejects per job sheet.

Do you guys have any ideas where does the coating precipitate came from? We already made sure that the lens are clean (checked right before dipping into coating tank) and the ovens are clean also. Where the precipitate came from is worrying. Because it disturb the long-running production.