de-rusting anchor chain

Binman said:
Is that the same chemical as brick acid, I would use.
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No "brick acid" is usually hydrochloric acid. It'll remove the rust and the rest of the galvanising and leave the metal in a very active state.

Phosphoric acid more suitable for rust removal as it will leave a protective phosphate coating but it will do the galvanising no favours.

10 to 30 % if you really want to use phosphoric acid
 
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Phosphoric acid is very nasty stuff. I would go a very long way to avoid using it.
Unless the chain is stainless then why remove rust unless you are going to stop it rusting again right away ? - and the best way to do that is to get it galvanised.
My thought would be to find a local galvaniser who can pickle the chain to remove rust and then re galvanise if necessary.
 
If you take it to a re-galvaniser you may find they have a minimum weight charge. Your chain alone may be nowhere near that minimum. If that be the case you could team up with local skippers to ensure a reasonable charge.
 
Thanks for your comments.
The chain is very rusty - certain shackles stuck to each other and would require a hammer to separate them. So, the galvanising is long gone. Difference with hydrochloric acid, which would indeed leave the surface highly reactive, is the phosphate layer that passivates the surface. What I like about that, is that I could do this on my own. Besides, most anchors have a grey colour which in my opinion is also a phosphate layer not galvanised.
 
After a recent experience with Italian? chain purchased from a well known Caribbean chandler that had rusted badly after 18 months I would be very cautious with rusty chain.

Mine had some galvanizing left on some of the chain. But after chipping away at the crusty bits I found this. These links were approximately in the center of the most used part of the chain.

View attachment 53228

It has been suggested that my chain was recycled Fiat and Lancia with the thinnest possible galvanizing.

BTW Towing the chain along the beach works. Just file the environmental impact statement first.
 
Thanks for the warning! We have to think out of the box. I think my chain is much too long anyway, sometimes clogs. What if I just cut off the worst part? How long should the chain be? I will make this a separate thread.
Erik
 
ErikKiekens said:
Not sure about anchors being phosphated but does not look like galvanised.
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Every steel anchor that I am aware of is galvanised. Hot dip galvanising is normally at least 50 microns in thickness. The galvanising process generates a series of iron-zinc alloys from iron below to pure zinc on top. Although the new zinc is shiny, once it wears or oxidises away the various alloys are revealed, grey to black in colour. Iron phosphate is normally only a few microns thick, with poor abrasion resistance.
 
if you want to de rust try Molasses. get it from your local equestrian supplies, its used to feed horses.. mix it 10:1 with water and leave whatever you want to derust in it for a few weeks.. i use it with old landrover parts to good effect. works faster if you knock off the thicker rust with a hammer..
 
If you want to get rid of the rust steep the chain in a 10% molasses solution for two weeks then treat it with phosphoric acid to stabilize the cleaned surface.
Then oil or paint it or galvanize it.
Molasses is by far the best way of removing rust from awkward shaped surfaces.
 
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