I noticed some spots on the glass of my Nauticam flat port. They look like thin mineral deposits and I can’t get them off. I always rinse the port with fresh water after dives, but usually don’t dry or wipe it afterward.

Any suggestions on how to clean them, or are they permanent?

Thank you,
Vitaly

I see the same on my housings. I was told it is the coating. I was also told to ignore it. YRMV.

Dry the port and water-contact optics after rinsing to avoid this, using a lint-free cloth. I try but it's not always top of mind after a dive. Can we really see water spots on a lens when shooting underwater?

Allowing water to evaporate on the glass is what causes this, the salts concentrate and it will eventually etch the glass, the same with anodizing on the housings. If you can't remove it with glass cleaner then it appears the glass has become etched. You can replace the port glass. The solution is prevention. I keep my housing covered after dives and it gets a long soak after each days diving before being dried off. I'm using a blower now from wolfbox, the high velocity blows the water off rather than letting it evaporate.

Hi,

I use Ceroxid (Cerium (IV) oxide).

It is a powder widely used as a high performance polishing agent in the glass industry. I bought some stuff on ebay but it shoud be available on internet shops as well. Watermarks are easily to remove and I was even able to remove small scratches with. I do it without polishing machine, so it takes a bit of time. But worth to do it.

Br Markus

2 hours ago, Muellema said:

I use Ceroxid (Cerium (IV) oxide).

I was told the glass has a coating, so any polishing compound might damage or remove it.

Hi,

any coatings on UW- ports are on the inner surface.

Br Markus