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Neoprene port covers damage wet glass?


Lewis88

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Reading through the recent UW Photo Guide article "How to Set Up and Maintain Your Underwater Camera" and this excerpt caught my eye. 

 

"However, if you have a glass port, make sure that you never attach a neoprene cover while the glass is wet with salt water. This can damage the port and create permanent burns on the glass. Make sure the dome is rinsed with fresh water and dried thoroughly before applying a port cover."

 

I've never heard this. Is this true? I bring my neoprene cover for my Zen DP100 on the dive with me, getting in and out of the water with it installed. Am I doing damage to my port?

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Correct, the neoprene dome cover can damage the glass! If you take the cover with you on a dive, it is soaked with salt water. Attaching it to the dome port, the salt water will dry on the glass and can cause damage to it.

 

What you can do is using two port covers: one for protection during handling the camera for diving and another one that stays dry and is only used after the dive.

Otherwise you can keep the neoprene cover and the dome wet if there is no chance to rinse it properly (maybe between two tank dives), because the salt water will only damage the glass if it dries on it.  As long as it is wet, it is not a problem.

 

So yes, don't leave your neoprene cover on the dome after the dive, if it dries ist can cause damage!

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2 hours ago, ChrisH said:

Correct, the neoprene dome cover can damage the glass! If you take the cover with you on a dive, it is soaked with salt water. Attaching it to the dome port, the salt water will dry on the glass and can cause damage to it.

 

What you can do is using two port covers: one for protection during handling the camera for diving and another one that stays dry and is only used after the dive.

Otherwise you can keep the neoprene cover and the dome wet if there is no chance to rinse it properly (maybe between two tank dives), because the salt water will only damage the glass if it dries on it.  As long as it is wet, it is not a problem.

 

So yes, don't leave your neoprene cover on the dome after the dive, if it dries ist can cause damage!

on the mohs hardness scale.. salt is 2.5, glass 5.5-6. Salt won't scratch glass other than really long term erosions with some energy behind it. It can however scratch coatings that aren't designed or choosen for a high mohs rating. You can get coatings between 6-8 fairly easily and I would hope most glass domes the manufs are doing that... but YMMV.

That said, keeping a done wet until after rinsed and then dry it properly is important but I worry more about staining than scratches with glass ports. From a technique POV you gave good advice

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A neoprene port cover significantly slows drying of the port surface and this is a significant benefit.  The article is wrong because it is incomplete, the port cover needs to dry out to cause the damage, but this is not going to happen on a day boat unless you leave your housing in the sun. 

 

If you are going to apply your port cover you need to be sure to keep the neoprene wet.  My experience shows when shore diving around home I apply the port cover coming out of the water and leave it on between dives and the transport it home, the cover is still wet several hours later.  The port cover is soaking wet as it has been in the water with me. 

 

Leaving a port uncovered to sit between dives the surface will dry out and the drying out is what causes the damage as the salt become more and more concentrated as the water evaporates.   You also do not want to have fresh water dry on the port - when drying it blow off excess water and wipe/polish with a clean micro fibre cloth.

 

I would not apply a dry port cover to a port when getting out of the water as it will absorb water and the dome surface can dry out.  The port cover is removed as I pop the housing into fresh water to soak and it is also rinsed out then soaked to remove salt.

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Seen issue with the salt deposit on the glass.

I was clearly able to see the mesh pattern of the neoprene cover on the glass.

This disappear with cerium oxyde cleaning (my glass had no coating, so it is not a problem)

 

Now, I use the neoprene cover during the dive for protection, and have a hard cover used afterward.

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I'm not sure about what effects (if any) salt may have, but I've personally scratched a 140mm glass dome following a shore dive because some sand or similar particulates got trapped between the neoprene cover and the dome and scraped against the glass when I tried to take the cover off.

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This is all interesting, and seemingly something I had never considered before. 

 

It sounds like the biggest risk is salt water drying on the lens via the soaked cover, which shouldn't happen if you rinse gear properly.

 

I typically leave the wet cover on the lens between dives on 2 tanks trips, and then rinse my lens and neoprene cover in the rinse tanks. I leave the cover on overnight and it's still damp the next morning. When doing my final soak and dry after my trip is over, I let them dry independently. 

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I am totally new to all this, but just received my first dome yesterday (used). Since this is a 10 cm Minidome for a pen housing I was thinking of getting a cap-type cover for it. Essentially a plastic hood that does not touch the glass of the dome.
How should that be used to prevent the staining marks?
 

Edited by Klaus
Autocorrect wrong
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21 hours ago, cerich said:

on the mohs hardness scale.. salt is 2.5, glass 5.5-6. Salt won't scratch glass other than really long term erosions with some energy behind it. It can however scratch coatings that aren't designed or choosen for a high mohs rating. You can get coatings between 6-8 fairly easily and I would hope most glass domes the manufs are doing that... but YMMV.

That said, keeping a done wet until after rinsed and then dry it properly is important but I worry more about staining than scratches with glass ports. From a technique POV you gave good advice

The salt does not scratch the glas. But it will cause glass corrision. The glass corrosion can not be polished (at least to my knowledge). 
So it is not advised to let a wet neoprene cover dry on the glass dome!

It is however only a problem if it dries! As long as the neoprene cover and dome stays wet, it is safe afaik. 

 

Seacam advice is the same:

„Entfernen Sie unbedingt die Neoprenschutzhaube nach jedem Tauchgang und Wässerung Ihres Gehäuses und montieren Sie diese erst wieder, wenn Glas und Neopren trocken sind. Trocknet der Neoprenschutz am Glas kann es zu teurer Glaskorrosion kommen, die nur vom Hersteller fachgerecht repariert werden kann.“

https://www.seacam.com/de/faqs/

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52 minutes ago, Klaus said:

I am totally new to all this, but just received my first dome yesterday (used). Since this is a 10 cm Minidome for a pen housing I was thinking of getting a cap-type cover for it. Essentially a plastic hood that does not touch the glass of the dome.
How should that be used to prevent the staining marks?
 


Hey Klaus

 

A plastic cap-type cover doesn’t have much impact. As Chris sets out above, the important thing is to prevent liquid, salt or fresh water, drying on the dome. Rinse when possible with fresh water and then dab dry with a soft cloth. If it’ll be a while before you can rinse it, keep the dome from drying out. 

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Salt water is not a problem for glass, you dive in it after all.  As this water evaporates the salts become more concentrated and I expect the pH will also increase and eventually reach the point where the glass can be etched.  This is a slow process and repeated evaporation events are needed before it becomes obviously visible.

 

A plastic cap could work but only if it is tight fitting to prevent the water that evaporates from escaping once humidity reaches 100% under the cap no more evaporation.  Most improvised caps won't be able to seal well enough to be useful.

 

Glass corrosion or etching can be removed but requires much more effort.  Glass domes will be ground and polished to reach the surface finish that they require - same as glass lens elements.  People report using cerium oxide for this and this is a common polishing agent for optical glass, however it requires much more elbow grease to have any impact.

 

A neoprene cover should be adequate.  If the weather is hot re-dunk it occasionally or add a splash of water from a drink bottle.

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18 hours ago, Kamaros said:

I'm not sure about what effects (if any) salt may have, but I've personally scratched a 140mm glass dome following a shore dive because some sand or similar particulates got trapped between the neoprene cover and the dome and scraped against the glass when I tried to take the cover off.

 

This is why I don't use neoprene covers. Of course, whatever cover/cap you use, it is important to dry off the glass before the water has a chance to evaporate.

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Yes but sand is a separate issue.

I've scratched several polycarbonate domes with neoprene covers too. Sand or salt particles on the cover inner part are polycarbonate worst enemy.

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