What should I use to remove rust from Anchor Chain?

[McIntoshUSA]

I have read allot of suggestions. Use CLR, use pool hydrocloric acid, vinegar, drag it behind a truck, sand blast it, use http://www.westmarine.com/buy/ospho--rust-converter-metal-primer--P012222196

Has anyone had good results in cleaning rust from your anchor chain?

Thanks

 

[thinwater]

Why? Unless you are in the process of re-galvanizing, you are going to loose zinc. If you are re-galvanizing the chain, the shop will do that as part of the price, whether you have done it or not.

 

[woodster]

We used to drag them in the sand to get them ready for IG inspection

 

[rgranger]

Do you own a battery charger? You can put the chain in a plastic tub (kiddie pool?) with some salt water, hook the negative lead (black) to your chain and the red lead to a piece of sacrificial iron (rebar works well). Don't let the rebar touch your chain and both the chain and rebar have to be in the same solution and the solution has to be isolated from ground (why we use plastic tub). Put it on 10 amp and let it sit for several hours. The rust will turn into a blue/black soot-like material (Fe3O4) that you can easily remove with a wire brush.

 

[JamesG161]

Do you own a battery charger? You can put the chain in a plastic tub (kiddie pool?) with some salt water, hook the negative lead (black) to your chain and the red lead to a piece of sacrificial iron (rebar works well). Don't let the rebar touch your chain and both the chain and rebar have to be in the same solution and the solution has to be isolated from ground (why we use plastic tub). Put it on 10 amp and let it sit for several hours. The rust will turn into a blue/black soot-like material (Fe3O4) that you can easily remove with a wire brush.

Wow! I had to think about that one. rgranger, quit making me think.

Fe3O4 is found in nature and is call Magnetite. Guess why? Normal red rust (Fe2O3) is NOT magnetic.
But be careful with this technique because...

You should be bubbling Hydrogen gas (inflammable)...

My chemistry may be a bit "rusty"

Jim...

 

[JamesG161]

Has anyone had good results in cleaning rust from your anchor chain?

Ask the US Navy. They use Naval Jelly which is different from Navel Jelly.
Most people who chemically remove rust quickly are using Phosphoric Acid (which in a milder, easier spread form called Naval Jelly).

Caution again...

All acid treatment also remove some galvanization from the non-rusty links.

If you make the link, bare clean iron, you have a very short time to re-prime it before rust begins again.
Check this link for what I have used for minor rust fixes.
http://forums.sailboatowners.com/index.php?threads/learning-about-anchor-gear-locker.174762/
Jim...

 

[rgranger]

Wow! I had to think about that one. rgranger, quit making me think.

Fe3O4 is found in nature and is call Magnetite. Guess why? Normal red rust (Fe2O3) is NOT magnetic.
But be careful with this technique because...

You should be bubbling Hydrogen gas (inflammable)...

My chemistry may be a bit "rusty"

Jim...

Rusty....
Yes it is magnetite.... a similar process of using super heated steam on hot iron will "blue" the surface... which is what is done to preserve the metal in steel girders used for construction.... also magnetite.

 

[centerline]

Rusty....
Yes it is magnetite.... a similar process of using super heated steam on hot iron will "blue" the surface... which is what is done to preserve the metal in steel girders used for construction.... also magnetite.

I know that I dont know it all, so I cant argue this... but I want to know it all, so in my quest to learn more I must ask the question, where and how is this process you speak of completed?... is it something that is done by somebody or some company after it leaves the steel mill?

I have been working with steel, steel beam/girders, bridges and high rise building construction most of my working life and have never heard of it before. galvanize or paint is the usual and most common protection for steel against the elements.

rust is NOT magnetite, but is iron oxide.... magnetite is just one of the minerals that Iron is made from, (actually a form of iron in its natural state) and the steel used in construction is the iron that has been alloyed with other minerals, but magnetite is not added back in.

it is correct that new steel is blue, but this blueing is in no way a purposeful intent, but a by product of the heat needed to form it to shape as it passes thru the rolling mill. the blue is commonly called "mill scale" and when a rust protection coating is needed, the blue mill scale has to either be sandblasted off or chemically removed so the coating will adhere to the bare metal without scaling/flaking off...

sometimes (almost always) the smaller metal shapes will be sprayed with a very light coat of vegetable oil as it leaves the mill for immediate rust protection, but this process makes the metal look almost black....

to answer the OP's question, no matter what you use to remove the rust will also inadvertently remove some of the galvanizing that may be on the chain... the quickest and easiest way to remove the rust is to soak the chain in a strong acid overnight, as it will remove ALL the rust on the chain. then rinse it very well.
the real challenge is how to keep it from rusting again after removing the rust....
the easiest to obtain "strong" acid is muratic acid which is sold anywhere concrete supplies/products are sold.... home depot, lowes, ect...

 

[McIntoshUSA]

Do you own a battery charger? You can put the chain in a plastic tub (kiddie pool?) with some salt water, hook the negative lead (black) to your chain and the red lead to a piece of sacrificial iron (rebar works well). Don't let the rebar touch your chain and both the chain and rebar have to be in the same solution and the solution has to be isolated from ground (why we use plastic tub). Put it on 10 amp and let it sit for several hours. The rust will turn into a blue/black soot-like material (Fe3O4) that you can easily remove with a wire brush.

I tried this for about 6 hrs yesterday and it did not seem to really do very much. My battery charger is an automatic battery charger so it it normally pulls the amount of amps it needs. Hence; It was pulling near zero amps I guess since it did not register a battery needing the amperage. Could this be the problem? There is not a way on my battery charger to manually set the amperage.
Thanks

 

[McIntoshUSA]

to answer the OP's question, no matter what you use to remove the rust will also inadvertently remove some of the galvanizing that may be on the chain... the quickest and easiest way to remove the rust is to soak the chain in a strong acid overnight, as it will remove ALL the rust on the chain. then rinse it very well.
the real challenge is how to keep it from rusting again after removing the rust....
the easiest to obtain "strong" acid is muratic acid which is sold anywhere concrete supplies/products are sold.... home depot, lowes, ect.

I had thought about using muratic acid. I did not know if the acid would actually weaken the chain leaks? If it would then I was wondering if it is best to just leave the surface rust and not worry about it? I have had several people say that the surface rust is normal and really not a problem.

 

[thinwater]

Yes, it will remove much of the zinc and some of the steel, causing it to rust even faster. The only reason to remove rust is just prior to painting or other coatings. The rust does not hurt anything per se, it is only evidence that the zinc is going and your are starting to loose steel.

Basically, the rust slowly eats the chain, an either now or soon you will need a new chain. You might try wire brushing 1-2 links to get an idea of how much metal is missing. I'm guessing you have a relatively small amount of small chain, so re-galvinizing probably does not make sense.

 

[JamesG161]

Is your objective cosmetic or remove surface corrosion and slow down corrosion?
Chain...
1) Each link is made from steel bar stock, bent and welded. 1/2 inch bar stock = 1/2 inch chain link.
2) You size your link/chain by the force you want to hold.
3) Standard hold strengths are designed to 140% of rating. Why? Corrosion/Erosion
4) Common boat chains are "hot dip coated" with zinc... or galvanized to reduce corrosion by water by letting the zinc corrode first. Once zinc is gone, the steel ( mainly iron ) "rusts" (Fe2O3).
5) We bang, scrape, dump and jerk chain in its use for an anchor.
6) Famous saying, but true... "A chain is only as strong as its weakest link!"
Corrosion...
1) You can only reduce the corrosion rate.
2) Acids corrode.
3) Sea water corrodes faster than fresh water.
4) Constant water on chain will corrode faster. Anchor locker should be just in air and not have water standing in the locker (most lockers have a drain to NOT plug) nor rain/bow spray constantly bathing the anchor.

Post a picture of your chain and also measure the diameter of the bar stock on a good link and worst link and reply for more help.
Jim...

PS: In my post#6, I show a forum link that has some Loctite® and Rustoleum® trade mark products web links I showed. The one that has Naval Jelly as a picture of a tall can of spray for rust remover/primer that works!

 

[capta]

You want to be very careful how much you remove from your chain if you are using a gypsy. Once you have removed this rust what do you plan to use to keep it from rusting again? There isn't anything you can spray or paint on it if you actually use it, that will stay for any length of time.
Save yourself all the hard work, time and expense of a job not worth doing and just replace the chain.

 

[centerline]

I had thought about using muratic acid. I did not know if the acid would actually weaken the chain leaks? If it would then I was wondering if it is best to just leave the surface rust and not worry about it? I have had several people say that the surface rust is normal and really a problem.

maybe you should do a bit of research on steel and rust to help you understand some of the answers given.
its steel chain... and whether it ever had any galvanizing on it, or if it is bare steel, its very obvious there is no longer enough protection to keep it from rusting. so removing any of the rust, will just create a clean steel surface that will allow more rust to form....

the rust is only a problem in as much as it stains the gelcoat.... rusting is a slow erosion process of the chain, but this slow erosion is greatly speeded up when the rust coating is continually removed and allowed to rust again... this is because the coating of the rust is an oxide that does its best to protect the metal that the oxide grows from/on. when the oxide is continually removed, there is nothing to protect the steel and so it erodes away at a quicker pace as it trys to get its protective coating back. its the continual erosion that makes the metal of the steel links thinner, which weaken the links.

the rust vs steel will be removed in acid, depending on its specific alloy, will be close to a rate of 25:1, so the thin layer of rust can be removed overnight, where the same thin layer of steel will take 25 times as long.... BUT...as the rust is removed, the acid is used up and the solution is weakend, so by the time the rust is gone, the "eating" properties of the acid are much reduced and may not affect the steel at all, even if left for weeks afterwards... but keep in mind this is dependent on how much acid is used and how much rust it has to "eat"... a fully rusted chain in a 5 gallon bucket just covered with the acid will be fine for at least 3-4 days, but there would be no need to leave it that long as even heavy rust would be gone within 12-24 hours...a normally rusted chain like you would find on old tire chains or tiedown chains can be completely rust free in 6hrs....

an acid bath does not change the alloy of the chain so the strength remains.... but again, the rust will begin to return in a couple hours.. so if you still think you need to remove the rust from your anchor chain, start reading from the top again about what happens when the rust is continually removed from steel...

this is not just my recommendation, but it is a fact of nature... if you want to stop your anchor chain from rusting, have it galvanized.
paint may protect it only until the chain is used again, because paint is NOT durable on chain and will scratch/rub off easily due to the way a chain is used.

 

[zeehag]

drag it thru sand a while. then vinegar then paint or galvo

 

[JohnShannon]

My anchor chain is all rusty, I am thinking of using a credit card

 

[centerline]

My anchor chain is all rusty, I am thinking of using a credit card

I think that should work just fine... and its a lot less work.

 

[rgranger]

I know that I dont know it all, so I cant argue this... but I want to know it all, so in my quest to learn more I must ask the question, where and how is this process you speak of completed?... is it something that is done by somebody or some company after it leaves the steel mill?

I read about this in a book on a chapter on metallurgy... The citation specifically mentioned the girders used in high rise and bridges but I don't know if that is common... Sorry I don't know more than that....

I have used the battery charger method to clean up an old trailer winch once. Worked fine. I got that idea here a long time ago.

 

[JamesG161]

I had thought about using muratic acid. I did not know if the acid would actually weaken the chain leaks?

After wanting to kick rgranger in the shins for making me think....
I thought about and reviewed the chemistry and reread all the posts. Everyone is right.

Muratic acid or HCl is a bit too harsh on galvanized metal. It does little to remove rust, but goes after the Iron and Zinc metals.

Phosphoric Acid (H3PO4) is used by professional painters, and of course the US Navy.
It actually reacts with the rust and not so much with Zinc and Fe.

Well is it is dang hard to brush on Naval Jelly on each chain link.

Where can I buy Phosphoric Acid?

You can use that old Muratic Acid to make it!
Go to you Home Improvement Center and buy TSP concrete cleaner (TriSodiumPhospate), dissolve 2 cups in few gallons of water, and carefully pour in about 1 cup of Muratic acid. Mix well. You should not smell any Muratic Acid in the mix. If you do, add some more TSP. This makes Phosphoric Acid and cheap too.
Put your rusty chain in the mix.
2 H3PO4 + Fe2O3 → 2 FePO4 + 3 H2O
You react the rust and NOT the Iron or Zinc so much.
Watch the rust change colors from red to yellow brown as it makes FePO4.

Now if your eyes didn't glaze over and you had an urge to drink a beer and watch TV, then blame rgranger.
Jim...

 

[Kings Gambit]

I've used the Naval Jelly to remove rust from a motor mount beneath a leaky water pump on my diesel. [Pump is now fixed.] Worked well, but took more than one application to get all of the rust off. It's tough to imagine doing a whole chain that way--expect slow work to get it "clean." There's the rust-treatment product Ospho that you mention above which was described in the January issue of Sail, where one soaks the item to be treated. See also at URL below but the product can be purchased in small quantities from Amazon [rather than WM]. I'd probably try sand blasting. However, I have SS chain so I have not had to deal with it personally.

http://www.ospho.com/