Re: Old Brass lens - white crystal-powder - Zinc oxide?
- I would think you are correct - Zinc oxide is the most likely culprit. Not sure about removal. I thing I would be very cautious - perhaps wet a Q-tip with distilled water (the universal solvent) and gently attempt to remove the crystals. But since I am not an expert, I am not sure I'd touch them unless they make the lens unusable.
--- In email@example.com, dcolucci@... wrote:
> Opening up a very early Harrison petzval lens revealed a clump or white
> crystal/powder clinging on the interior of the lens barrel. Is this Zinc
> oxide from the brass? How best to remove this?
> Any help appreciated.