Anchor chain and zinc oxide.

[sarabande]

I have an anchor chain ( unused but with zinc oxide on the galv surface).

If I put it into dry domestic concrete mixer, and churn it for a few minutes, will that polish the chain and remove the white dusty stuff please ?

Connect the ends with a good shackle so the mixer doesn't tie a most humungous granny knot .

Thanks

 

[Neeves]

The zinc salt is soft and will erode quickly. You could put it in a concrete mixer but could equally use the chain as a rode and the zinc salt will disappear after one 'use'.

Zinc salts, Google 'white rust,' is commonplace - usually because the location in which it is stored is damp

Jonathan

 

[sarabande]

Yep, I'm familiar with the way that plain zinc galvanising is so soft (mohs scale) that it heals a scratch by "creeping" across the wound, but was hoping someone might have polished a zinc oxide chain in a mixer (perhaps with some plain water as the oxide is slightly soluble) to renovate the surface finish.

I'll give it a try later today and take some pics before and after. I just prefer shiny galvanised chain to dusty, gritty links.

 

[Neeves]

I'm not sure that it is only zinc oxide, it maybe a mix of oxide and hydroxide - not that it makes any different to what you want to do. But the gal is not soft - the zinc is soft (so any zinc on the chain will be soft) but the alloys that form during galvanising, alloy mixes of Zn and Fe, are harder than underlying carbon steel. These alloys are metallurgically bonded to the underlying steel - they are removed in the rode by abrasion. Considering these alloys are only, typically, 70 microns thick, and they will last on a liveaboard's yacht for 3-4 years its quite a stunning result - wear of approx 20 microns a year. With galvanising you want a thick, but not too thick, alloy level. There is a sweet thickness - too thick and the alloy bond weakens and the gal coating 'flakes'

Because the zinc is soft it does not last very long on the chain (in terms of the life of the chain) - its abraded off by the seabed - leaving you wth the hard alloys - that then will last for a long time. But you are correct the zinc being soft can take knocks and be self healing - but its not a big factor in galvanising of an anchor chain. White rust might be unsightly but once you use the chain it will be worn off and you will then have a chain coated with the meat - the alloys.

It is likely your cement mixer might be contaminated with.....cement, sand and fill - which will abrade the alloys - just process for a short period or you will remove the alloys (on which you depend for their resistance to oxidation (rusting).

It counter intuitive - its a rode, it gets wet - if you only use it once - perfect environment for white rust (until the zinc is worn off) - but if you clean, as you propose, wash with fresh water and then keep the chain dry- allow air to circulate - you should have a thin layer of polished zinc and most of the coating will be 'inert' gal alloys.

Jonathan

 

[LittleSister]

As my anchor chain is at any time either in the anchor locker or underwater, I haven't given a high priority to it looking smart.

For those of a more fastidious nature, I've heard people mention tying their anchor chain to a vehicle tow bar and taking it for a drag along a road or gravel track to clear off the worst of the oxidation. I've no idea how effective or advisable it is.

. . .
It counter intuitive - its a rode, it gets wet - if you only use it once - perfect environment for white rust (until the zinc is worn off) - but if you clean, as you propose, wash with fresh water and then keep the chain dry- allow air to circulate . . .

My own chain is somewhat oxidised. Most remiss of me not to thoroughly clean and dry the chain after every time I anchor.

. . . Connect the ends with a good shackle so the mixer doesn't tie a most humungous granny knot .

You are curiously confident of that. My own experience is that gremlins are adept at tying knots in any chain, rope or electrical wire the moment you look the other way, and I don't expect that tying the ends together would deter them one bit.

 

[Fr J Hackett]

I would be concerned about wearing some of the galvanising of the chain.

 

[Neeves]

As my anchor chain is at any time either in the anchor locker or underwater, I haven't given a high priority to it looking smart.

For those of a more fastidious nature, I've heard people mention tying their anchor chain to a vehicle tow bar and taking it for a drag along a road or gravel track to clear off the worst of the oxidation. I've no idea how effective or advisable it is.


My own chain is somewhat oxidised. Most remiss of me not to thoroughly clean and dry the chain after every time I anchor.

You are mistaken. The advice of pulling the chain along a beach or even a quiet road is to remove oxidation of the exposed steel when the gal has worn through. It has little to do with the OP's desire to remove 'white rust'. Iron oxide is harder than white rust and takes a bit more effort to remove. But the advice is given to those who are going to re-galvanise their chain - it would really not be sensible to drag good chain along a beach - you will simply shorten its life.

If you don't care about your chain looking smart and leave mud on the chain then the mud itself may host anaerobic creatures that exude sulphur containing product which will dissolve the gal. This is a major problem in muddy rivers

If you don't wash your chain, for example with the same frequency as you wash the deck, you are simply encouraging rusting of the chain (or acid attack of the gal) which will occur with greater rapidity if the chain is left with a coating of salt water and worse mud. Most owners seem reluctant to spend money unnecessarily and looking after your chain will allow it to last longer - if your wallet is fat you will not care.

As the OP seems a reputable member I would assume he will seize the shackle and mouse it with wire

Jonathan