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Cold Galvanising

jddevel

By jddevel
in Boat Building & Maintenance

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dmr Veteran II

dmr

Posted
Posted

In Hot dip galvanising there is an interchange of atoms at the steel-zinc interface, a sort of local zinc-steel alloy is formed which is said to be even harder than the parent steel itself.

Cold galvanising is a fancy name for painting.

................Dave

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Bee Veteran

Bee

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Posted

I'm not sure what this is, it does mention cathodic protection quite a lot, presumably that means the body of the hull but then an anode is just a big lump of zinc or something similar fixed to the hull. I'm not very convinced to be honest. Years ago I used a Sigma zinc rich two pack primer as a first coat on a hull, that was a straightforward paint and the last time I looked most of it was still there, I think I would trust it above the galvatech but I am not a scientist.

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cuthound Veteran II

cuthoundDonate to Canal World

Posted
Posted (edited)

My boat, built in 2007 was treated with Zinga and then expoxy blacking up to the first rubbing strafe above the waterline. Never been retreated to date.

At its survey when I bought it in 2014 there was zero corrosion, flaking or pitting. There was however a thick layer of freshwater mussels.

She is due out of the water early next month for inspection, possibly reblacking. 

I will let the forum know what I find.

Edited by cuthound
To unmangle the effects of autocorrect.
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Neil2 Veteran

Neil2

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The problem with a lot of the "new" approaches to narrowboat hull protection is there isn't enough feedback yet from owners who have gone down the Epoxy, Zinga, Hot Zinc spraying, Keelblack, etc route.   

For example, we had our boat hot zinc sprayed at Debdale a couple of years ago, (it was also epoxy coated) and IIRC they said maybe 60 boats had been through this process at that time.  So it's going to be some time before the claims made for this treatment are proven.

At the moment the suppliers of, and those who apply, the variety of coatings on offer these days can make all sorts of claims for them that may take many years to properly scrutinise. 

The reason we went down the hot spray route is when you see the investment that has gone into the plant at Debdale it is very clear that the company is in it for the long haul.  You have to consider this with any treatment that is supposed to last ten years or more.

 

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Chewbacka Veteran

Chewbacka

Posted
Posted
15 minutes ago, Neil2 said:

.............................The reason we went down the hot spray route is when you see the investment that has gone into the plant at Debdale it is very clear that the company is in it for the long haul.  You have to consider this with any treatment that is supposed to last ten years or more.

 

Very wise, but probably more accurate to say they 'hope to be in it for the long haul', if it turns out to be as good as they think maybe I'll give it a go.  Any idea how much per foot?

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Neil2 Veteran

Neil2

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Posted
4 hours ago, Chewbacka said:

Very wise, but probably more accurate to say they 'hope to be in it for the long haul', if it turns out to be as good as they think maybe I'll give it a go.  Any idea how much per foot?

When ours was done it was £24 per square metre for the zinc spraying, and the same rate for the grit blasting ie £48/sqm altogether plus VAT I think.

Of course that doesn't include lifting, preparation etc.  that's all extra.  There's a choice of what to put on top of the zinc, - black, epoxy, comastic etc most people seem to have something although it isn't strictly necessary.  There's also stuff like repainting the tunnel bands.

It does seem very expensive, but when you compare it to the cost of a say a professional cabin repaint I think it represents far better value for money.  I've not had the boat slipped since it was done, but I will post a report when I do, maybe later this year. 

 

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Detling Rising Star

Detling

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Posted

Not a boat, but I painted a trailer with Gavlafoid many years ago (20ish) maybe 2-3 coats, It has been in and out of sea water and fresh water a few dozen times a year and left parked out in the rain all year. It still has almost no rust, only where it has been scraped, so my verdict is it does work.

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Flyboy Experienced

Flyboy

Posted
Posted (edited)
1 hour ago, Detling said:

Not a boat, but I painted a trailer with Gavlafoid many years ago (20ish) maybe 2-3 coats, It has been in and out of sea water and fresh water a few dozen times a year and left parked out in the rain all year. It still has almost no rust, only where it has been scraped, so my verdict is it does work.

Galvafroid was made by Expandite  but I don't think it is available any more. It was used a lot on electricity pylons so must have been effective.

Edited to add that is still made by a different company.    http://www.fosroc.com/product/show/galvafroid

Edited by Flyboy
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Neil2 Veteran

Neil2

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1 hour ago, Flyboy said:

Galvafroid was made by Expandite  but I don't think it is available any more. It was used a lot on electricity pylons so must have been effective.

Edited to add that is still made by a different company.    http://www.fosroc.com/product/show/galvafroid

I'm amazed they sell it at all with a name like that.  Why choose a name that begs the question how do you pronounce it?

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peterboat Veteran II

peterboatDonate to Canal World

Posted
Posted

My boat is zingered as well, it was also zinger blacked which went silver! I took it out the next year and keelblacked it, the zinger was totally intact no marks nothing and we all know that at the waterline after a year with conventional blacking deterioration occurs. So is it worth it ask me in 20 years when the best of the rest are putting new bottoms on

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Flyboy Experienced

Flyboy

Posted
Posted
2 minutes ago, WotEver said:

Well, the oid in sangfroid isn't pronounced 'oyd', is it? 

Correct, Neil2 asked if it was pronounced like sangfroid and I replied 'no, it's like the oid in celluloid. I 

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WotEver Veteran II

WotEverDonate to Canal World

Posted
Posted
2 minutes ago, philjw said:

Could it be that the froid part is from the french for cold? If so then it would sound like "galvafwa"

I would think that is indeed the derivation of the name - cold galvanising / Galva Froid

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Flyboy Experienced

Flyboy

Posted
Posted
2 minutes ago, philjw said:

Could it be that the froid part is from the french for cold? If so then it would sound like "galvafwa"

I think that is true and that the name was derived from French.. The original manufacture Expandite called it with a pronounced D. I used to have a lot of dealings with Expandite so know this to be true.

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