On 6/4/2026 at 3:47 PM, Muellema said:

Hi guys,

Here is my "silly question" again. Can someone please explain the rationale behind applying the coating to the outer surface of a port? Does anyone have a technical or optical justification for this?

I do not know the optical sense, but the problem with coating on outer surface is, that we clean/wipe the port after every dive. Even if we use the softest cloth available, we inevitably remove a little bit of the coating each time—however minuscule that amount may be. Unless there is some specific optical purpose for it... why put the coating on the outside of ports? However, I’m certainly open to being corrected if someone can offer a clear explanation for a reason for outer surface coating on ports. May be there is difference on super macro lenses due to optical setup. Hope someone can help.

I use ceroxyd for years for my ports and my old macro wetlens and it works perfect. It removes watermarks and even tiny scraches without much effort.

Also Seacam confirmed that optical coating is on the inside of the ports.

Let me give you also two other example not UW related

-first not from the field of optics- but still related to the loss of coatings. I had my car's paintwork treated with a very expensive ceramic coating (a very hard coating). After three years—and very few hand washes the coating was virtually gone due to the washing process and environmental exposure and it had to be reapplied.

-second from my optician. I have glasses with expensive progressive lenses with hard coating for protection. My optician recommends to clean this one only with warm dishwashing liquid and use a supersoft close (no standard microfiber, no standard glasses cleaning cloths) to dry. He too, assured me that otherwise, the coating wouldn't last for a terribly long time.

May be our UW camerahousing supplier have a superformula coating😁

Best regards,

Markus

Hi Markus, what’s the exact product name / manufacturer for your ceroxyd?

Where do you find it?

Greetings and thx

Michi

5 hours ago, Michi said:

Hi Markus, what’s the exact product name / manufacturer for your ceroxyd?

Where do you find it?

Greetings and thx

Michi

Hi Michi,

I bought my cerium oxide on an online platform called hood.de (similar to eBay), though that was a few years ago. I don't recall the brand name. However, during my research at the time, I found out that there are quality differences reflected in the color of the cerium oxide. Yellow and light cream-colored varieties are the purest and are used in the semiconductor and optical industries. Reddish-brown versions contain slightly more impurities and aren't as pure. These are primarily used in the glass industry for polishing glass. I have the reddish-brown type (see photo), and in my opinion, it yields very good results on the ports.

Br Markus

2 hours ago, Muellema said:

Hi Michi,

I bought my cerium oxide on an online platform called hood.de (similar to eBay), though that was a few years ago. I don't recall the brand name. However, during my research at the time, I found out that there are quality differences reflected in the color of the cerium oxide. Yellow and light cream-colored varieties are the purest and are used in the semiconductor and optical industries. Reddish-brown versions contain slightly more impurities and aren't as pure. These are primarily used in the glass industry for polishing glass. I have the reddish-brown type (see photo), and in my opinion, it yields very good results on the ports.

Br Markus

Hi Markus, thx a lot! That´s very helpful! Greetings

Have these blotches on my 75 dive old Nauticam port, and I have always meticulously kept and rinsed it in fresh water after every dive. I learned from Nauticam that I need to rinse it with deionized water to be sure ... A new one for me. I guess if you don’t have that at hand (!) keep it wet most of time and when you dry it—use a clean soft towel to wipe it off and make sure it’s absolutely dry.

3 hours ago, Christian K said:

Have these blotches on my 75 dive old Nauticam port, and I have always meticulously kept and rinsed it in fresh water after every dive. I learned from Nauticam that I need to rinse it with deionized water to be sure ... A new one for me. I guess if you don’t have that at hand (!) keep it wet most of time and when you dry it—use a clean soft towel to wipe it off and make sure it’s absolutely dry.

I have it too on my Nauticam port but it didn't show on video.

42 minutes ago, Davide DB said:

I have it too on my Nauticam port but it didn't show on video.

I haven’t done any tests since I discovered it, but glad to hear. And my hunch is it won’t have any impact as it will be wet.

12 hours ago, Davide DB said:

I have it too on my Nauticam port but it didn't show on video.

Yes, this is the same type of stain I have on my port as well - ugly when dry, but doesn't show up when wet (on video at least)

9 minutes ago, bghazzal said:

Yes, this is the same type of stain I have on my port as well - ugly when dry, but doesn't show up when wet (on video at least)

Be interesting to test it out, the test case would probably be shooting into the light, like a sunball or something.

12 hours ago, Chris Ross said:

Be interesting to test it out, the test case would probably be shooting into the light, like a sunball or something.

yes it looks bit muddy, not sharp when shooting into the light, specially when shooting without any strobe or video lights

On 6/8/2026 at 1:19 PM, KiruKakuni said:

yes it looks bit muddy, not sharp when shooting into the light, specially when shooting without any strobe or video lights

I would suggest you try polishing with cerium oxide others have reported it works, you would just need to sure the materials used when polishing have no grit in them- you need to get optical grade material, this link talks about it:

Polishing vs Regular Grade Cerium Oxide: How To Choose?

Discover the essential guide to choosing the right grade of cerium oxide for your polishing needs. Learn the differences between Polishing and Regular Grade cerium oxide, including insights on purity,

@Chris Ross Thank you. I will check where I can get online.

I bought some cerium oxide (brown powder) quite a while ago on Amazon, but I never worked up the courage to use it on my Nauticam WWL-1. I had noticed that whenever I did not use an air blower to dry the lens, it developed stains that were impossible to remove with regular cleaning methods.

After reading comments saying that the anti reflective coating is not on the outer surface, I decided to give cerium oxide a try. The results were very good.

I mixed the cerium oxide with water to make a paste. If the tap water in your area is very hard, it is better to use distilled water. I used two parts of water for every part of cerium oxide. The more diluted the mixture, the less abrasive it will be.

I recommend polishing it by hand with a microfiber cloth. Using circular motions and making several passes removed all the stains from the glass surface. Honestly, it did not take much effort, and the result was excellent. The glass now looks brand new.

2 hours ago, ArcoNaut said:

I bought some cerium oxide (brown powder) quite a while ago on Amazon, but I never worked up the courage to use it on my Nauticam WWL-1. I had noticed that whenever I did not use an air blower to dry the lens, it developed stains that were impossible to remove with regular cleaning methods.

After reading comments saying that the anti reflective coating is not on the outer surface, I decided to give cerium oxide a try. The results were very good.

I mixed the cerium oxide with water to make a paste. If the tap water in your area is very hard, it is better to use distilled water. I used two parts of water for every part of cerium oxide. The more diluted the mixture, the less abrasive it will be.

I recommend polishing it by hand with a microfiber cloth. Using circular motions and making several passes removed all the stains from the glass surface. Honestly, it did not take much effort, and the result was excellent. The glass now looks brand new.

Thanks for the feedback,

This is a recurring topic and every time we start all over again with all the usual advice. From Lourdes water to snake oil. I'm joking 😁

Actually we finally have proof that cerium oxide applied sparingly easily removes stains caused by water deposits.

I repaired the WWL twice from fairly deep scratches and received confirmation from Nauticam that the lens treatment is on the inside.

In my case the work was very lengthy and done by a professional.

I know it has been discussed before, but just as an additional data point, despite being a very careful sort, I did finally get some water spots on a flat port. I used Carpro CeriGlass Glass Polish from Amazon on a microfiber cloth and it took about 2 minutes to get the glass completely clean and then I rinsed/soaked it well to remove all the chemical. The spots had not been very bad, but had resisted all the usual glass cleaning methods. I also had some powder I was going to make into a paste and use if the liquid stuff did not work, but did not need it.

On 6/1/2026 at 8:44 AM, Walt Stearns said:

Here two things you can do to prevent this.

1.     Don’t allow saltwater or freshwater where there is calcium present in the water to dry on the glass.

If you can’t keep your housing in the rinse tank/bucket on the boat, wrap a wet towel around it.

2.     After the dive(s) when it comes time to rinse/soak your gear in freshwater, be sure to dry off the glass with clean dry towel or cloth as soon as that done to prevent water spots from lingering. Even my face-mask gets this treatment

I live in South Florida where our fresh water is loaded with calcium. If you allow them to dry in place they will leave micro deposits where they dry which are total bitch to remove afterward.

In addition to this I would add, don't put your wet neoprene cover back on after the rinse tank - dry the lens & put on a clean dry neoprene cover.

I always carry 2 neoprene covers on each dive trip - one for the boat ride/getting in/out of the water and one after the rinse tank & wiping it down - if your small boat doesn't have a rinse tank, at the least wipe the salt water off the lens and cover it with a towel if in direct sun

On 10/11/2026 at 3:36 PM, JMC22 said:

In addition to this I would add, don't put your wet neoprene cover back on after the rinse tank - dry the lens & put on a clean dry neoprene cover.

I always carry 2 neoprene covers on each dive trip - one for the boat ride/getting in/out of the water and one after the rinse tank & wiping it down - if your small boat doesn't have a rinse tank, at the least wipe the salt water off the lens and cover it with a towel if in direct sun

Drying the lens can prove difficult, depending on your boat. I advocate putting the wet cover back on and leaving it there, covering with towel etc to prevent it drying completely. It stays on till you get back and you can give your housing a soak. Obviously don't leave it on overnight just till you get back to shore or to a rinse tank where you can give it a soak. I take a foldable cooler with me to protect the housing on the boat and at the end of the day it becomes my personal soak tank.

The stains are caused by the water droplets evaporating and drying out. My treatment is a soak then use my air duster to blow all the water off the ports and housing.

On 10/15/2026 at 5:40 PM, Chris Ross said:

Drying the lens can prove difficult, depending on your boat.

I put a simple microfabric towel in my drybag to use to wipe down the lens dome if there are no freshwater rinse tanks on the dive boat, then cover it with a towel - then back at the resort or live aboard, do the full routine of rinse, blow off, dry & store

4 hours ago, JMC22 said:

I put a simple microfabric towel in my drybag to use to wipe down the lens dome if there are no freshwater rinse tanks on the dive boat, then cover it with a towel - then back at the resort or live aboard, do the full routine of rinse, blow off, dry & store

I do the same. This has worked very well for many years with no issues on the ports. Taking the time to properly clean and blow dry it when back in the room is the key.

I use a micro fiber cloth to final dry or even between dives, I carry and bag of them. I also have an electric battery powered blower. It has two (lipo) battery packs, cost about $80. It will blow all the water out of buttons and off a lens or port or housing in a jiffy after a freshwater rinse. Worth the additional battery pack weight. It is a tiny little thing but produces a lot of velocity. I blow dry my camera between dives unless it is a short interval and the camera can stay wet.

Glad to hear the polishing is working. That is reassuring there is a solution for film and spots. Now about that white haze that develops on Nauticam housings despite intense efforts to keep it from happening is aggravating as all h-e-----.

Edited 16 hours ago16 hr by Nemrod

15 hours ago, Nemrod said:

I use a micro fiber cloth to final dry or even between dives, I carry and bag of them. I also have an electric battery powered blower. It has two (lipo) battery packs, cost about $80. It will blow all the water out of buttons and off a lens or port or housing in a jiffy after a freshwater rinse. Worth the additional battery pack weight. It is a tiny little thing but produces a lot of velocity. I blow dry my camera between dives unless it is a short interval and the camera can stay wet.

Glad to hear the polishing is working. That is reassuring there is a solution for film and spots. Now about that white haze that develops on Nauticam housings despite intense efforts to keep it from happening is aggravating as all h-e-----.

I'm just curious why you wouldn't carry something like one of the below and avoid the extra equipment, batteries, etc. for a blower? You have an almost unlimited supply of compressed air and most of these nozzles are pretty good at regulating airflow if you don't blast them open all the way.

https://www.divegearexpress.com/adapter-hq-air-nozzle-bc-inflator-qd-post

https://www.amazon.com/Scuba-Choice-Diving-Standard-Connector/dp/B006UM7F28/

Regards,

Brett

23 minutes ago, TmxDiver said:

I'm just curious why you wouldn't carry something like one of the below and avoid the extra equipment, batteries, etc. for a blower? You have an almost unlimited supply of compressed air and most of these nozzles are pretty good at regulating airflow if you don't blast them open all the way.

https://www.divegearexpress.com/adapter-hq-air-nozzle-bc-inflator-qd-post

https://www.amazon.com/Scuba-Choice-Diving-Standard-Connector/dp/B006UM7F28/

Regards,

Brett

Hi, Brett,

That’s a really good question. The answer is the pressure from those nozzles is far too strong to blow out under the buttons without potentially damaging the o-rings.

The trick is to have enough pressure to gently blow out any residual water without putting undo pressure in the tiny o-rings. The battery powered blower (I use one similar) has settings to adjust the force. I find I will often use the lower power when concentrating on the buttons and then a higher speed with cleaning the dome.

I personally find using a blower does a better job than a towel for final cleaning at the end of the day or before storing.

Enjoy!

Chip