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how to stop Verdigris?


shanson

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(For those of you, like me, that didn't know Verdigris is the green stuff that appears on fittings with copper on them)

 

I'm stripping my engine and noticed a bit of Verdigris on my raw water pump, It's seems to be able to be cleaned off but how can I stop it comming back?

 

Cheers

 

SHANE

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You have to coat it with a protective coating. Several products are available, like Nyalic for instance. Or even just a clear Polyurathane. But you have to make sure the bronze is clean. Very clean and even then, it is hard to get these coatings to last. As soon as water manages to get under the coating, it doesn't take long.

 

BUT!!! there is a completely different coating available to try. Easiest way to track it down is to do a quick search on trademe for a product called Metaflux. This stuff is quite simply amasing. Contact the guy that is selling this stuff and ask him if this will work. Personally I think it will. He has a range of metal spray, but the one I am thinking of is his Brass coating. It is NOT PAINT. It is actually metal in a spray can. So it will look just like the pump metal, but the stuff does not corrode. Well... at least it hasn't in the situations I have used it in.

For others reading here, you have to check this stuff out. The range covers SST, Brass, Copper, Aluminium and Zinc. Because it is a Metal and not a paint, if you apply substantial heat, the coating will actually meld into the sub metal. You can take an exhaust manifold and coat it in Aluminium or SST and it becomes part of the sub metal and will withstand heat just like it does as a solid metal.

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You need to get the Brass one. It isn't currently listed, so I linked to the Copper one. Ask the guy for the Brass spray. But also ask him if it will stop the stuff from occurring. I think it will. I have never had anything grow on materials I have sprayed thus far. Nor does it seem to tarnish out in the weather. The copper one does not either. I spray a piece of bare Steel with a test patch of each coating and have left it outside to test it. It has been 8mths now of Rain and Sun and nothing has happened to the coating, but the bare steel uncoated has certainly rusted.

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Very interesting Wheels - thanks

 

You may be able (or others) to answer a related question:-

 

I have hard salt crystals forming on salt water engine intake seacock.

 

There is no evidence of leaking and I slow it down a bit with boiling water rinse every 6 months or so.

 

My concern is that if/when I need to remove it, the build up will be almost impossible to remove from threads.

 

FYI - it is bonded back to the keel anode

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I have heard an engineer (head-down and with a fair number of expletives mixed in) express the view that this effect can occur in different levels depending on the marina. He described it more as a "calcification" than what you might be thinking with your reference to the anode.

 

In our case, with a saltwater-cooled Bukh, the biggest issue was what was building up internally and this was fixed by flushing with an acid solution (a job for someone who knows what they are doing = not me). This solution was introduced post-water pump and I imagine it would not necessarily be kind to rubber seals etc. It resulted in quite a significant improvement in the amount of water coming through the system. At the same time the guy took away the water pump and some other parts and cleaned them up at his workshop, I imagine with a similar solution.

 

None of the above will assist with what is going on with your intake but it might suggest that it is worth spending a bit to find out if it is having an effect elsewhere. And it wasn't an expensive job, can't quite remember because there was other work taking place at the time but I am thinking around $350 at the upper end.

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Salt crystals can only get there from Saltwater. It could be that the weep is very slow or is it even possible that Salt water in the bilge may slap against the thing when it is a little ruff. Then it dries. Fresh water rinse every now and then will be worth the effort I think and probably all you can do really. As for removing at some date in the future, they are a pain anyway and most likely you will have to wreck it to remove it. A good thread sealant at time of assembly is the only safeguard against future freezing up of the threads. Just make sure you can and do turn the Seacock on and off to ensure the Valve inside does not freeze up. Providing you see no pink spots on the Bronze, the thing will last many years. Don't get caught in that snake oil Salt remover product. Salt is one of the most easily dissolvible minerals on the Planet. It is why it is dissolved in such huge quantities in Oceans. Calcium and Rust are a different beast as Murky has pointed out. Hydrochloric Acid is often used to flush these contaminants out. But two other more friendly acids are Phosphoric and Glycolic Acid. These are both non-toxic and will work well at removing deposits.

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Thanks again Wheels

 

Could be a slow weep or result of salt water from a clean out I do (see below)

 

Anyway not exactly keeping me awake at night and will continue with a periodic fresh water bath.

 

The acid thing is interesting and I have noted it

 

Since discovering I had a marine farm between the intake grill and top of seacock I give a periodic clean out with sail batten plus close the seacock after use - I also keep the key by the seacock - and that was the result of a forgetfull moment resulting in a melted exhaust silencer, engine room full of melted plastic and exhaust smoke - turned on seacock which enabled the engine room to now fill up with ocean, through melted silencer etc etc - a complete weekend cleaning plus many $$ for silencer was a lesson!!

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Oh yeah, been there, done that, Twice!!!!....still need to get me the T shirt though. Those plastic Vetus silencers and lift boxes are stupid expensive and a rip off in my view. There is a guy in Auckland making Fibreglass ones. Powerflow I think the name. Well worth the expense as they don't melt.

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