Coppercoat on stainless steel

tolhurstorganic

tolhurstorganic

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The Coppercoat applied to stainless rudder fittings has lasted 3 years but is coming off in big flakes. everywhere else it is sound.
Spoke to Coppercoat who tell me that CC as it is an epoxy will not stay on s. steel for more than a few seasons, they have no suggestions. Roughing up the steel is the only thing I have come up with other than cleaning of CC and doing with conventional anti-foul
Anybody know of any treatment that may help CC to adhere?
 
tolhurstorganic said:
The Coppercoat applied to stainless rudder fittings has lasted 3 years but is coming off in big flakes. everywhere else it is sound.
Spoke to Coppercoat who tell me that CC as it is an epoxy will not stay on s. steel for more than a few seasons, they have no suggestions. Roughing up the steel is the only thing I have come up with other than cleaning of CC and doing with conventional anti-foul
Anybody know of any treatment that may help CC to adhere?
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Nope. And I've tried.
 
It is possible, and done frequently, to apply epoxy coatings to props and saildrives. I'm not quite sure why stainless would be different. Speak to International as they have instructions for applying Interprotect - and if you can apply Interprotect I cannot see why not CC (nor CC over Interprotect?)

But its all about preparation, getting a good keyed surface, then clean, clean and clean. For saildrives (I know aluminium) but same with props, grind with 60 mesh, it has even been suggested 40 mesh, wash with degreaser, wipe with dilute acid, wash with water, final clean with acetone - do not touch with bare hands (wear surgical gloves) and then paint (or coat). The acid wash is approved by some not others - edit: but cannot do harm on stainless?

Jonathan
 
J Neeves said:
It is possible, and done frequently, to apply epoxy coatings to props and saildrives. I'm not quite sure why stainless would be different. Speak to International as they have instructions for applying Interprotect - and if you can apply Interprotect I cannot see why not CC (nor CC over Interprotect?)

But its all about preparation, getting a good keyed surface, then clean, clean and clean. For saildrives (I know aluminium) but same with props, grind with 60 mesh, it has even been suggested 40 mesh, wash with degreaser, wipe with dilute acid, wash with water, final clean with acetone - do not touch with bare hands (wear surgical gloves) and then paint (or coat). The acid wash is approved by some not others - edit: but cannot do harm on stainless?

Jonathan
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Tried all sorts of keying methods and epoxies. The best types are solvent free. It lasts a while but will come off in a big sheet.
 
Elessar said:
Tried all sorts of keying methods and epoxies. The best types are solvent free. It lasts a while but will come off in a big sheet.
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From memory - you ought to know:). But what then is your recommendation - for stainless.

But it also beggars belief that International, or someone else, have not mastered the problem. Stainless is hardly exotic and it does find application, under water - and thus needs AF (of some sort).

What, if anything, is special about stainless?

Jonathan
 
J Neeves said:
But it also beggars belief that International, or someone else, have not mastered the problem. Stainless is hardly exotic and it does find application, under water - and thus needs AF (of some sort).
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I'd be interested to know the number of steel hulls in use in the market. If the market is not very big why would any company spend time and money researching something for no return?
 
Camelia said:
I'd be interested to know the number of steel hulls in use in the market. If the market is not very big why would any company spend time and money researching something for no return?
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I am sure I have seen stainless props around, though confess have not seen any stainless hulls.

I have been assuming PropSpeed are making money, they could simply be altruistic of course.

Jonathan
 
J Neeves said:
Good stuff - though I'm not sure that about the comment regarding zinc and embrittlement - but I am sure a metallurgist will set me straight:(

Jonathan
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Paints that contain metallic zinc should not be used on stainless steel as embrittlement of the stainless steel substrate can occur in the event of severe fire damage.
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Correct, but note the words "severe fire damage"
 
Just rambling here... Before the advent of solvent free epoxies, I would often use (my favourite) screwdriver to mix and apply araldite for a multitude of jobs. Of course it stuck so hard that it had to be ground off in the end. Considering that CC advise the use of an epoxy tie coat on GRP prior to application, would an old style epoxy work for this on SS?

Rob.
 
rob2 said:
Just rambling here... Before the advent of solvent free epoxies, I would often use (my favourite) screwdriver to mix and apply araldite for a multitude of jobs. Of course it stuck so hard that it had to be ground off in the end. Considering that CC advise the use of an epoxy tie coat on GRP prior to application, would an old style epoxy work for this on SS?

Rob.
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Unfortunately PBO missed a trick here. They recently (last month) did a piece on sticking epoxy to aluminium and mild steel but ignored stainless, which I would have thought far more useful. We used to mount metallurgical specimens in epoxy where we could not use a conventional hot press and it always seemed to stick to stainless reasonably well. I would think that with good abrasion there should be a reasonable chance.
 
'Better' yacht builders often have a steel frame around which the yacht is built, X-Yachts being a nice example. I appreciate not stainless but I had fondly imagined the frame was bonded to the fibreglass (with epoxy).
 
J Neeves said:
...I had fondly imagined the frame was bonded to the fibreglass...
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It would be nice to think so, but consider reinforced concrete as a parallel. So long as the metal remains sealed in contact with the surrounding material it carries the load and remains protected from the elements.

Rob.
 
I suspect the real problem is that stainless steel (like all steels) expands and contracts with a combination of stress and temperature.

Epoxy on the other hand is extremely brittle when applied muck like a paint with reinforcing material. I do not think that adding cloth to the resin would fix this problem, but it might improve it.

So, based in the above a flexible layer (rather than cloth) between the steel and the resin may provide the required flexibility for the steel to grow/shrink but not effect the epoxy.

Just wondering if a layer flexible sealant would be enough?

Any thoughts.

Good luck and fair winds. :)
 
oldsaltoz said:
I suspect the real problem is that stainless steel (like all steels) expands and contracts with a combination of stress and temperature.

Epoxy on the other hand is extremely brittle when applied muck like a paint with reinforcing material. I do not think that adding cloth to the resin would fix this problem, but it might improve it.

So, based in the above a flexible layer (rather than cloth) between the steel and the resin may provide the required flexibility for the steel to grow/shrink but not effect the epoxy.

Just wondering if a layer flexible sealant would be enough?

Any thoughts.

Good luck and fair winds. :)
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Your suggestion (thank you) of a flexible layer on s.steel is worth a try. Nothing much to loose, so thinking I will coat fittings with 2-3mm of waterproof mastic allow to dry then epoxy over the top.
 
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