rusty old galvanised deck fittings: bollard, cleats, tabernacle etc

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retsina

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My 37 year old Macwester Wight has a lot of original galvanised fittings: bollard, cleats and tubernacle. The tubernacle and the bollard have lost the galvanised coating and therefore rusty but solid and plenty of metal left. It will be easier and cheaper to protect them rather than to change them. Paint does not last long and is not hard wearing. I am thinking to use two part epoxy heavy coating, but I can only find it in black colour. Any ideas how to give the fittings new life?
 
have them regalved do a search for bods near you down here the local indespension trailer people do it.
 
Re: rusty old galvanised deck fittings: bollard, cleats, tabernacle et

Get them re-galvanised. Most galvanisers have a minimum charge (or minimum weight) but if you find a local blacksmith who regularly sends stuff off to a galvanising company, you may be able to add yours to his next consignment.
I did this for all the fittings on my last boat - mast bands, goose neck, all the steel stuff inside the original blocks etc, and they came back like new. Don't forget your anchor if you need to make up some weight. I also letter punched mine to identify them.
 
Epoxy coating is in effect paint. It won't work for long as it gives only a barrier protection and no electrolytic protection like galvanizing does. And you need both.
Any barrier coating is good until its perforated (scratch etc), then the rust starts underneath like cancer and pulls the rest of the coating off. And its not just scratches. MOst paints are porous to a degree, so they'll rust.
Re-Galvanizing is the only sensible option to refurbish galvanized steel.
 
To date - there is still no paint or other coating that will remove rust or coat it well enough to prevent the rust breaking through again within a short time. If someone can prove me wrong I and he (she) could end up very wealthy. Why were all those fittings galvanised to begin with?
So to prevent further troubles, as has been said remove them and get them re-galvanised.
 
I had a Macwester 30 and I guess the fittings were identical to yours. I cleaned them up as well as I could with emery/wet + dry and the steel wool. I then applied about 2 or 3 coats of silver/grey Hammerite. Make sure you apply them as per the instructions and let the paint go hard before you use the fittings. This lasted well for about 4/5 years and then I cleaned them up again and repainted. This worked well enough for me.
 
I've sprayed the anchor-end of my anchor chain with cold galvanizing spray this year and I am surprised and very impressed with the quality and strength of finish. Worth a try, you have little to lose, and I think you'll be happy with the finish.
 
Re: rusty old galvanised deck fittings: bollard, cleats, tabernacle et

I used an anti rust epoxy paint to paint a launching trolley that is continually wet. Doubled the repainting time from every year to every second year. From the look of the ingredients it has aluminum particles in it.
 
There is no such thing as "cold galvanizing". If its not hot its not galvanizing. Zinc melts at about 419 degC, and galvanizing normall is done at about 450C.
There are products which claim to be "cold galvanizing", but are really zinc rich paint.

This type of product (Galvafroid is one such, just a brand name) has the advantage of zinc particles suspended in paint, and so some electrolytic protection is afforded as well as barrier protection. They have the disdvantage that the zinc is bound in a resin and not electrically available to the electrolyte (sea water), and so somewhat ineffective until the paint is abraded, revealing the zinc.
The biggest advantage of zinc rich paints is that application can be done insitu (except for the underside of mountings, bolted connections etc). The finish is paint however, and is as hard (soft) as paint, and not as hard as real galvanizing.
Real galvanizing has all its zinc continually exposed to the electrolyte, and so all effective (until all consumed). The alloy layers that make up a galvanized coating (there are 4 layers to this coating), are both soft (outer layer) and therfore impact resistant, and hard (inner alloy layers) - in fact harder than mild steel, and this combination of hard and soft gives abrasion resistance about 400 times paint, and impact resistance.
Real galvanizing also has the advantage that where scratched, even right through the coating to reveal steel, will "self heal". That is the surrounding zinc protects the exposed steel, even up to about 5mm wide scratches. It might go brown, but won't severely corrode.
 
[ QUOTE ]
There is no such thing as "cold galvanizing"

[/ QUOTE ]This is a term in common use to describe the application of zinc paints to the surface. The term has been used for decades or longer - e.g. the brand 'Galvafroid'.

Also, electroplated zinc is also 'galvanising' and is very common on components such as shackles. Unfortunately plated Zn tends to be very thin and that's why so many galvanised shackles don't last the season.

I agree with you about the possible problems with cold galvanising and agree that it does not replace hot dip galvanising but it does have its place especially when used over previously galvanised parts that cannot easily be removed - which was the OP's situation. I suspect that some zinc paints are better than others - mine shows zero ohms on a multimeter when I hold clips gently on the surface, some centimetres apart.
 
I guess its hard for a real galvanizer to accept the term "Galvanizing" for all these half measures.
Electroplated zinc is much thinner (typically 8-10 microns) than hot dip galvanizing (80-100 microns), and the life expectancy is directly proportional to the thickness.

Zinc rich paints vary hugely in quality. Many contain much aluminium to brighten them, and that metal doesn't do much in this context. A simple way to tell the corrosion protection quality of zinc rich paint (ie zinc content) is to feel the can. If it doesn't feel extraordinarily heavy, then its not much good.
Very good zinc rich paint will have over 90% Zinc in the dry film.

Your Ohm-meter test isn't a bad one, but remember that the Zn particles aren't connected, so you can't expect continuity. They are individually bound up in the paint's resin. If they were electrically conected, then there would be far better corrosion protection from that system.
 
I've dug my can of spray zinc out and yes, it is very heavy indeed. It is branded Maurer part No. 88376 "Zincante Freddo Spray" "Cold Zinc Spray" distributed by Ferritalia. I bought mine in Spain. It is very quick drying and while the don't state the ingredients they tell you to clean spills with acetone. It is very easy to use, has low ohms, and gives a very pleasing finish. To those who have difficulty in getting things hot-dipped (it is almost impossible here, cheaper to buy new) I would say give it a try.

Edit:- Just to reiterate, these zinc particle must be in direct contact with each other since the ohms read zero. Presumably when the solvent evaporates they come into contact, but surface finishes isn't my subject.
 
I agree galvafroid paint is very good for touching up, I've used it for touching up boat trailers where the galvanising has worn away and its a quick and easy way of giving it extra life.
 
I Galvafroid my deck fittings and a couple of coats will last about 4 years. Which for a couple of hours work I think is good going.

I urb em down with sandpaper or wire brush, mask off and cover deck to preven spashing. then slap it on.
 
Theres a map of Spanish Galvanizing plants here
http://www.ateg.es/FRMiembros.htm

Paints mostly don't dry just by the evaporation of the solvent. (A few do, but these are becoming rare). Most dry by either a chanmical reaction between 2 components (as in 2 pack), or by a reaction activated by moisture content of the air. There is still solvent to thin the paint. So the resin that set the paint solid, (could be polyester, polyurethane, epoxy etc) is what binds the filler (zinc particles) together. Its this that seperates the particles of zinc, insulating them from each other (electrically).
 
Thanks for the list. There is a minimum quantity acceptable to the most local ones I'm told that in the past several people have clubbed together to have their chains glavanised but it hasn't caught on here in Almerimar.

As for metallic paints, many metallic paints conduct. As I mentioned, the zinc spray I have conducts (I suspect that it is very zinc rich and the solvent evaporates). As a young engineer in the early 1970s we had silver paint - genuine silver - that conducted very well indeed, and could be used to repair pcbs so there is nothing new about it. Re-reading your posts I am not exactly what you are saying but if you are saying that (all) metallic paints do not conduct then you are mistaken.
 
Lemain

I misread your comment about conductivity. You said "zero ohms", and I read zero conductivity! My error.

Some metallic paints conduct, some don't, depends on the binder and the metal, and metal content.
Conductivity of the cured paint is a good sign of effective corrosion protection potential.
 
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