Losing the green.

All of my thru-hulls have that green coating of corrosion (before I fixed the bonding system), is there a simple method to clean it off?

Thanks!

Tom-

Many love the green patina of true bronze, I'd not call it corrosion. Many high end homes find the green patina of high priced copper roofs a status symbol.*Most silver polish/cleaners will work, but with most bronze castings "rough" it is quite a chore (toothbrush work)*to keep them looking like factory fresh bronze. After cleaning put some protective spray like Corrosion Block*on them.

any acid will work...like toilet bowl cleaner "the works" or* from boatyards mary kate "on- off"....I wouldn't leave it on long and wash thoroughly...then spray with some water displacing fluid.

psneeld wrote:
then spray with some water displacing fluid.

Click to expand...

*I've tried 39 different formulas... Should I try one more? :-D

Why Dont'cha?

I have the same problem from an improperly installed block zinc that has since been repaired. I have sprayed some areas with Fluid Film which helped some.


-- Edited by Forkliftt on Saturday 19th of November 2011 07:56:58 PM

GonzoF1 wrote:
All of my thru-hulls have that green coating of corrosion (before I fixed the bonding system), is there a simple method to clean it off?

Click to expand...

*Here's something for you to think about.* I saw this on a rare-coin site.* It said that---

"While a patina (the hard green coating on most bronze coins) is the result of corrosion, a patina actually seals and protects coins."

But before you get to thinking that the green is always good, the article goes on to talk about what they call "bronze disease" which is also green but is the result of electro-chemical corrosion of copper and copper alloys (like bronze).* So the character of the green coating will depend on what's going on with the component and the "environment" that it's in.

When we first got our boat we were in a dealer slip next to a brand new Krogen.* On our 1973 boat, just about all the exterior hardware--- stanchions, cleats, door hinges, nav light housings, vents, etc. are bronze.* On the Krogen, all this stuff was stainless.* One day the Krogen owner, who spent a lot of time polishing his stainless rails, stanchions, etc, looked over at us and said, "You people with older boats are really lucky.* You don't do squat to your bronze hardware, it turns green, and everyone tells you what a great looking boat you have.* If I don't keep all this stainless polished, everyone thinks I'm letting my boat run down."

All our through hulls and seacocks are green or green-ish, and they're all properly bonded.* Scratch them and they are shiny bronze colored underneath, not pink.* I think you will find the same situation on just about every boat with bronze hardware.* Unless you want the green gone just because you want the green gone, I don't think I'd worry about it.* Keeping them polished or not green is way too much work and will be as much an ongoing maintenance chore as varnishing exterior trim.


-- Edited by Marin on Saturday 19th of November 2011 10:34:54 PM

"On the Krogen, all this stuff was stainless. One day the Krogen owner, who spent a lot of time polishing his stainless rails, "

Sounds like the SS was not electro polished , so has the rust resistance of a kitchen pot.

Simple solution is JOY mixed with Ospho. Rub it on and let the Joy turn white , holding the Ospho in place.

Wash it off after an hour or two.

The Ospho will grab the loose iron , just as electro polishing does , so SS will rust less and less if you continue the treatment a few times.

Marin, Part of the reason I thought I was interested in removing it, now that I have fixed the bonding system, that it would be a good indicator that something was wrong again. Also, if corrosion is forming where I can see it, I suspect it's forming on and under the bonding connection. It appears I might be mistaken. Thanks.

Tom-

FF wrote:
"On the Krogen, all this stuff was stainless. One day the Krogen owner, who spent a lot of time polishing his stainless rails, "

Sounds like the SS was not electro polished , so has the rust resistance of a kitchen pot.

Click to expand...

No, he wasn't talking about poor quality stainless.* Just the need (in his view) to keep the stainless on his new boat polished like a mirror.* Hand prints, salt buidup, general dust and soot--- he didn't want his stainless to look like it had any of this on it.* So he polished it all.* About once every couple of weeks.

GonzoF1 wrote:
Marin, Part of the reason I thought I was interested in removing it, now that I have fixed the bonding system, that it would be a good indicator that something was wrong again. Also, if corrosion is forming where I can see it, I suspect it's forming on and under the bonding connection. It appears I might be mistaken. Thanks.

Tom-

Click to expand...

*Tom,

Mine are a bit*green and my bonding system is good.

JD wrote:Mine are a bit*green and my bonding system is good.

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*That is because the green patina has nothing to do with bonding or not bonding.

If you leave a bronze anything sitting on a teflon plate in the saloon long enough it will get a green patina.That is a good thing, it is a protective layer.

Okie-dokey then... I guess I won't waste my time. Thanks y'all.

If you have this. Then you need to wory about your bonding system.
Bronze Disease
Bronze Disease [BD] is to bronze metals, what rust is to iron based metals. The matrix of copper and tin that forms bronze is attacked by hydrochloric acid {HCl} to form tin chloride and copper.
"The first step in the electrochemical corrosion of copper and copper alloys is the production of cuprous ions. These, in turn, combine with the chloride in the sea water to form cuprous chloride as a major component of the corrosion layer:
Cu -e >> Cu⁺
Cu⁺ + Cl^- >> CuCl
Cuprous chlorides are very unstable mineral compounds. When cupreous objects that contain cuprous chlorides are recovered and exposed to air, they inevitably continue to corrode chemically by a process in which cuprous chlorides in the presence of moisture and oxygen are hydrolyzed to form hydrochloric acid and basic cupric chloride (Oddy and Hughes 1970:188):
4CuCl + 4H2O + O2 >> CuCl2 ⁰3Cu(OH)2 + 2HCl
The hydrochloric acid in turn attacks the un corroded metal to form more cuprous chloride:
2Cu + 2HCl >> 2CuCl + H2
The reactions continue until no metal remains. This chemical corrosion process is commonly referred to as 'bronze disease.' Any conservation of chloride-contaminated cupreous objects requires that the chemical action of the chlorides be inhibited either by removing the cuprous chlorides or converting them to harmless cuprous oxide. If the chemical action of the chlorides is not inhibited, cupreous objects will self-destruct over time." 1
*
SD

Friend of mine is an Engineer with metallugical training. I may have misunderstood, but on his boat all of the cleats are brown. His explanation is that they are bronze, so go brown over time. Only copper and brass go green. Bronze is copper and tin, brass is copper and zinc. So if your fittings go green, they must be brass, not bronze. Clear as mud?

Keith--- Take a look at the photos of the cleats and hawses on our boat that I posted for Superdiver on the "Hawse pipe" thread. They are all bronze, and they are not brown. They pass through brown on the way from being shiny new to being green. All the bronze exterior hardware on our boat is the same color. The cleats on the bulwarks are 38 years old. The ones mounted on the aft deck and the one we added to the foredeck are about ten or eleven years old.

My guess is that the color of the patina that develops on bronze will vary by the specific character of the bronze alloy that was used to make the part.* I believe all the bronze used on GBs is silicone bronze but I could be wrong, and I don't know if this would slant the patina more toward green than brown.

*


-- Edited by Marin on Tuesday 22nd of November 2011 09:44:57 PM

koliver wrote:
Friend of mine is an Engineer with metallugical training. I may have misunderstood, but on his boat all of the cleats are brown. His explanation is that they are bronze, so go brown over time. Only copper and brass go green. Bronze is copper and tin, brass is copper and zinc. So if your fittings go green, they must be brass, not bronze. Clear as mud?

I am not*an engineer with metallugical training, but I have some bronze on my boat in the bilge and it has a slight amount of green on it.* I had a sea strainer with a lot of green on it and I found that the plastic cover was cracked and allowing sea water in.

It has been replaced with a different style.*

Click to expand...

*

I am an engineer, metallurgical in fact. This gives me no special status on this Forum*nor do I expect it. As stated in previous posts, the "normal" green patina we see on quality bronze when it comes in contact with seawater is nothing to worry about. Unless seawater is quite acidic, which is not the case where I sail, the reactions supplied by**Skipperdude will not occur.


-- Edited by sunchaser on Saturday 26th of November 2011 09:24:04 PM