DIY Zinc Plating on Anchor Chain

You need (working A and B in centimetres)

A diameter of the wire from which the chain is made
B length of wire in one link (measure several to get a good average)

C Surface area of ONE link is Pi x A x B in cm sq.

Then you need

D number of links in 1 metre
E total length of chain in metres

That gives you
F (D x E) number of links in the whole chain

Use C x F for total surface area.



It looks a nasty and complicated process, and I am uncertain how passivated zinc will have enough thickness/hardness to resist the rough and tumble of an anchor chain. Do they give you any thickness of the coat achieved ?
 
nigelmercier said:
I'm considering DIY Zinc Plating my Anchor Chain, I've just got an email from Classic Plating that mentions this product.

Any thoughts on this?

It says it can zinc plate 43,000 sq cm, how do I calculate the area of my chain?
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Do consider that zinc plating (electroplating) only puts a thin layer of zinc onto the surface of the steel where as galvanizing puts a thick layer and alloys the zinc into the surface of the underlying layer.

In a marine environment zinc plating will only last a very short time.

Don't waste your money.
 
AntarcticPilot said:
With a VERY rough calculation, based on 6mm chain and guesstimates for the length of a link, it will do about 10m of chain.
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Thanks, I'll forget it then. I don't know why I didn't do the math myself...

[EDIT]
Circumference of 10mm chain is (π x d) = π cm or about 3 cm
Length of link, no idea, say 10 cm
So each link is about 30cm²

Pitch, 2 links give about 6cm [Ref]
So for 6cm of chain there are 2 links, or 60cm²
So 100cm of chain there is 1000cm²
So kit will do 43m?
Oh.
 
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There's another reason NOT to zinc plate an anchor and or chain.
The life expectancy of a zinc based coating is proportional to the thickness of the coating.
Zinc plating is often about 6-10 microns (a micron is 1/1000 of a mm)
Hot dip galvanizing is typically 100 microns. (10 times the life at least)
 
I echo the above comments about electroplating underwater boat stuff.

I do lots of little bits for old motorbikes and it works very well. I have also tried it with shackles and saltwater sees it off in no time. BTW you don't need an expensive kit, a low voltage DC source, a few plastic tubs and household chemicals do the job pretty well. Not so bright as the commercial item but fine for what it is.
 
I once used an electro plated chain hook, looked pretty when new, and it dragged on the seabed overnight. It had started to rust before I used it again. I had it sand blasted and then galvanised, it now works a treat.


Surface area of chain - look to Mr Google

One link - the Surface area of 2 cylinders + surface area of a toroid for the curves, times the number of links per metre x number of metres.

I think it works out at 4 x Pi (squared) Rr + 2Pi x r x H

Where r is wire size, H is length of straight of the link and R is the radius of the average of the crown.

But I'd check as I'm working from memory.

6mm chain (EN818 2 similar to DIN) worked out at 0.00103949 square metres per link

Its quite commonly used to calculate the thickness of gal on chain (weigh chain before and after acid washing, SG of zinc is known etc)

Jonathan
 
nigelmercier said:
I'm considering DIY Zinc Plating my Anchor Chain, I've just got an email from Classic Plating that mentions this product.

Any thoughts on this?

It says it can zinc plate 43,000 sq cm, how do I calculate the area of my chain?
Click to expand...

Calculate the length of steel rod making up the chain by taking weight of your chain in Grammes and dividing by the cross sectional area of that rod (in sq. cm.) and also by the density of steel (appr. 7.5 g/cu. cm.). You can then get to the surface area of this rod (in sq. cm.) by multiplying this length by pi times rod diameter.
 
It might be possible to do a short length of chain with the kit but it would be tricky.
The plating is not deposited evenly so that areas which are "line of sight" to the anode plate well, masked areas not so good and hidden areas (between the links) not at all. So you really need multiple anodes distributed around the bath and to move the work regularly in order to achieve and even plate.

I think a one foot length would be doable, in a fashion, but quite a task.
 
zinga - or similar spelling. Shop around the prices did vary a bit.

http://www.zinga.eu/

Clean the chain enthusiastically and then paint on a couple of coats. Lasted 5 years so far.

Carefully applied to the chain and not the surroundings I did about 50m of chain with 2 coats from 1 litre. Used it with their thinners for the first coat.
 
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If you want to use paint on your chain, this is probably the best one.
The downside of zinc rich paints is that the zinc particles are not electrically connected, and so the proper electrochemical protection doesn't happen. There are other paints, like Galvafroid and similar. A good way to tell if they're "good" is to lift the can. If it doesn't feel extraordinarily heavy, then put it back on the shelf. Zinc is heavy, about the same as steel, so if it doesn't feel like the weight is approaching that of a solid block of steel, it doesn't have enough zinc in it. Some paints add aluminium t make the coating brighter.

The upside of paint is low price and ease of use.

Watch out for zinc that's combined chemically with other "stuff". For example zinc silicate. Only metallic zinc gives the cathodic protection that you will need.
 
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Gwylan said:
zinga - or similar spelling. Shop around the prices did vary a bit.

http://www.zinga.eu/

Clean the chain enthusiastically and then paint on a couple of coats. Lasted 5 years so far.

Carefully applied to the chain and not the surroundings I did about 50m of chain with 2 coats from 1 litre. Used it with their thinners for the first coat.
Click to expand...

Thanks. I've used Zinga satisfactorily on an anchor but it's interesting that it has lasted well on your chain, with the mechanical wear between links.
 
Its the internet so I'm guessing :)

But painting steel for corrosion protection is going to be very dependent on the surface preparation and cleaning chain of any residual or current corrosion is going to be very difficult. A common method is to tow the chain behind a vehicle on a beach. You then have to ensure each links is coated, also difficult, given that all the links are interconnected. Finally longevity will depend on usage - the less you use it, obviously, the longer the paint will last. If you can fresh water wash and air the locker, after each use that will encourage lower corrosion.

If you use it frequently - then rust is not the issue, usage will keep it clean. Reduction in steel, abrasion, will be an issue - normal gal (in addition to reducing corrosion) also offers abrasion protection as the gal is harder than the underlying steel.

Knowing how long the paint lasts when marking a chain, for length, if it were us we would need to think of painting annually. It is very difficult to get a decent length of chain (it is inordinately heavy) off a yacht, especially on a swing mooring. When it gets to the point where rust is a real issue I'd take the easy option and have it regalvansied or buy new chain.

Jonathan
 
I used to use paint marks on my previous boat's anchor chain, and found that I had to renew them two or three times a year. If Gwylan can get paint to stay on his chain for five years, either it's b****y good paint, or his chain never gets wet. :D
 
I'll simplify my earlier contribution regarding weighing the chain by cancelling out some pi s. Weigh the chain (bathroom scales?) and then take trice the weight in Grammes and divide by the chain rod diameter and also by the density of steel which is nearer 7.75 Grammes per cu.cm than my previously guessed 7.5. That will give you the surface area in sq. cm.
Re. paint versus hot dip, I once attended a lecture on the latter and I recall that the effectiveness of the process is dependant on forming an interfacial layer of a zinc-iron compound which forms a strong bond. I have a 1930's galv. watering can which has always been outside and still resists rust although admittedly it has never seen a marine environment.
 
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