We are experiencing a 'line' during dip hardcoating which, at first sight, looks like a tooling scratch, but under the microscope is revealed to be a chain of very fine bubbles.
We have the same lacquer type in another machine where there is no problem, and we had the same problem in the original machine when there was a different lacquer type installed. The problem is not seen till the lacquer dip stage, but changing the pump, and even installing the lacquer in another tank on the same machine, does not resolve the issue. We are confident that there are no air bubbles in the system.
Has anyone ever seen anything like this before? Or has anyone any ideas what may be causing this?
P.S. the marked lenses are extremely difficult to strip, if this helps.
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