Corrosion at caseback

[rkim11]

I just read on another part of the forum that a Rolex can pit inside the caseback because the o-ring rubs off the protective film that 904L steel has to protect from corrosion. And the sweat from our wrists is the perfect solution to seep through this vulnerable area? Does that mean that everytime I sweat I should wash my Sub? Seems silly for a tool watch billed as rugged as a Sub right?

[Mickey®]

Every time you sweat wash your Sub? No but wash/clean it regularly. Also have it serviced every 5 - 7 years. The corrosion only gets in watch if seals are failing.

[77T]

Ummm...could you post a link to the thread where you read that in another part of the forum?

[rkim11]

http://rolexforums.com/showthread.php?t=113138

[Mickey®]

Originally Posted by 77T

Ummm...could you post a link to the thread where you read that in another part of the forum?

There is no doubt that Rolex cases can have corrosion....

[77T]

Originally Posted by Mickey®

There is no doubt that Rolex cases can have corrosion....

Wasn't in doubt - just wanted to read the original before answering. I hadn't seen it before.

[Mickey®]

Originally Posted by 77T

Wasn't in doubt - just wanted to read the original before answering. I hadn't seen it before.

[77T]

Originally Posted by rkim11

http://rolexforums.com/showthread.php?t=113138

Thanks - IMHO, I think what's missing in that piece is the self-healing properties of Cr2O3.

True, the Chromium Oxide is a film, but it chemically regenerates (or "heals") in contact with oxygen or molecules containing oxygen.

Intrusion of sweat or any other liquid behind the case back doesn't occur until the pressure exceeds the mechanical seal or the gasket degrades. I wouldn't worry about it as long as you keep up with regular service (and an annual pressure check if you dive).

[GMK]

I thought one of the advantages of 904L steel over 316L was that it was even less prone to pitting than 316L steel.

[77T]

Originally Posted by GMK

I thought one of the advantages of 904L steel over 316L was that it was even less prone to pitting than 316L steel.

True because it has 20% Cr vs. 16% Cr in 316L

[MoBe]

Originally Posted by rkim11

I just read on another part of the forum that a Rolex can pit inside the caseback because the o-ring rubs off the protective film that 904L steel has to protect from corrosion. And the sweat from our wrists is the perfect solution to seep through this vulnerable area? Does that mean that everytime I sweat I should wash my Sub? Seems silly for a tool watch billed as rugged as a Sub right?

Giving your watch a bath and a scrub in soap and water from time to time is a good idea but I would be more concerned about the effects of chlorine from pool water if I were you.

Chlorine is so corrosive that it will eat holes in stainless steel turning it into metallic swiss cheese over time so if you`re in a swimming pool on a regular basis then your watch will need regular washing.

[timelord]

especially those bromide salts found in spa baths. 304L has better resistance to bromides than chlorides whereas 904L is the other way around. There are many other stainless steel alloys known as super stainless steels or duplex that are even more corrosive resistant than 904L. I am not sure why Rolex used 904L which is expensive with almost 25% nickel and not as corrosive resistant as duplex. Check out the corrosion tables of bromides in
http://www.outokumpu.com/application....asp?name=SO08

and for all other chemicals that 904L is vulnerable

http://www.outokumpu.com/application.../corrstart.asp

[dooder202]

Originally Posted by timelord

especially those bromide salts found in spa baths. 304L has better resistance to bromides than chlorides whereas 904L is the other way around. There are many other stainless steel alloys known as super stainless steels or duplex that are even more corrosive resistant than 904L. I am not sure why Rolex used 904L which is expensive with almost 25% nickel and not as corrosive resistant as duplex. Check out the corrosion tables of bromides in
http://www.outokumpu.com/application....asp?name=SO08

and for all other chemicals that 904L is vulnerable

http://www.outokumpu.com/application.../corrstart.asp

I have no idea what these tables/charts mean. But I do know that 99.9999% of Rolex owners aren't going to come within 100 yards of those chemicals, nevermind on their watches...

OP: As long as you wash your watch down weekly, I cannot see it having any corrosion any time before we're all dead...

Look at some of the watches for sale on this forum that are 50 years old.. Not a tad of corrosion at all.

[MoBe]

Originally Posted by dooder202

I have no idea what these tables/charts mean. But I do know that 99.9999% of Rolex owners aren't going to come within 100 yards of those chemicals, nevermind on their watches...

OP: As long as you wash your watch down weekly, I cannot see it having any corrosion any time before we're all dead...

Look at some of the watches for sale on this forum that are 50 years old.. Not a tad of corrosion at all.

I`m sure lots of Rolex owners come in contact with salt water and chlorinated pool water.

[timelord]

Originally Posted by dooder202

I have no idea what these tables/charts mean. But I do know that 99.9999% of Rolex owners aren't going to come within 100 yards of those chemicals, nevermind on their watches...

OP: As long as you wash your watch down weekly, I cannot see it having any corrosion any time before we're all dead...
.

There are so many innocent common chemicals your 904L timepiece is vulnerable to. The table I posted is the corrosion table for various grades of stainless steel against chemicals tested over the last 70 or so years by the World Gurus of stainless. To answer your question, in the corrosion table for the chemical in question, O means almost no corrosion at all , Op means risk of some pitting, 1 means 1mm of pitting growth per year once pitting begins as it is next to impossible to stop.

I have a 904L Seadweller (not the Deap Sea) which has pitting where it butts on the helium escape valve which was discovered when I sent it in to a RSC for a service where I was quoted almost body and soul to replace the case and do a full service which meant that it would have been far more feasible to buy a new one. Also watch out for chlorination in swimming pools, Salt water, Sea water, Spa baths with bromide salts, cleaning chemicals including bleach and wash your hands after urinating as handling your 904L Rolex with unwashed hands poses a risk of Op for urine in 904L, see http://www.outokumpu.com/application....asp?name=UR02
As for washing or rinsing the timepiece, it is capillary action of fluids and osmosis that sucks in the oxidants or corrosive electrolytes between the seal and case back so I doubt whether rinsing would truly be an absolute way of preventing it. I rinsed my Seadweller daily to no avail.

[Andad]

Thanks all...very interesting read.
I don't wear my SD often but will have the case back off and check it out next week.

[le_baroudeur]

well.. Tests show that it is very hard to corrode 904l, timelord is apparently the only one here to have had corrosion problems on 904l , all the pitted caseback photos come from watches of the pre-904l era, where 316l rusts is 15 - 20 years of sweat, chlorine or sea water.
Timelord: did your caseback have problems or just the valve? I'm thinking of a factory defect in the alloy here... (i thinl that you came to that conclusion too if i remember correctly... )

[timelord]

Originally Posted by le_baroudeur

Timelord: did your caseback have problems or just the valve? I'm thinking of a factory defect in the alloy here... (i thinl that you came to that conclusion too if i remember correctly... )

Le-baroudeur, I wrote a thread about this on August 19,2011 in http://rolexforums.com/showthread.php?t=190495
where I almost fell into depression when I discovered that my beloved Seadweller was never going to be waterproof and was not going to be any more than a cosmetic piece for others to ask "is that a genuine Rolex?" which is not what I am about. Reading back I believe you also responded to my thread. Like most of you I paid hard earn't money for it and it wasn't cheap!!Worst part is that it is discontinued and I could never replace it new even if I wanted to!!

The corrosion was just inside around the section inside the case where hole of the case butts against the valve. I don't remember about any corrosion under the seal as I was already turned off by any corrosion in the case that was going to spread or get worse with time, very much like if your girlfriend betrays you with another lover. I was quoted in the $thXXX to have the complete job done including replacing the case and a service. I therefore decided to part with it as I was no longer in love with it and sold it for a quick sale for anyone wanting to keep it for spares for their Seadweller. I bought the watch when it was 5 months old in 2003 still with remaining warranty. One never knows what it was exposed to but there are chemicals that do corrode 904L -especially bromides (that are often found in Spa baths) more than chlorides. I do not want to sound cookey but even urine can corrode 904L if creeps between contact pieces of the metal. Perhaps even a factory defect, I will never know as I wasn't going to pay thousands to a metallurgist to do scientific research on it.