using Oxalic acid

[bbg]

I need to clean some rust off some metal. Specifically off the internal spindle of a winch.
I intend to use oxalic acid (in the form of teak cleaner that I bought to brighten up our garden furniture).
It is in sort of a gel form that will dry within a few minutes. My question is - how long do I leave it on? Will I see the rust disappear before I rinse / wipe it off? Or do I have to wait and the rust will disappear when I rinse / wipe. If I wait, for how long?

 

[omega2]

I need to clean some rust off some metal. Specifically off the internal spindle of a winch.
I intend to use oxalic acid (in the form of teak cleaner that I bought to brighten up our garden furniture).
It is in sort of a gel form that will dry within a few minutes. My question is - how long do I leave it on? Will I see the rust disappear before I rinse / wipe it off? Or do I have to wait and the rust will disappear when I rinse / wipe. If I wait, for how long?

Not intended for use on metal, and if it's polished the shine will go,

 

[bbg]

OK - then how do I get the rust off the winch spindle?
Will this product really damage it?
The problem I have is that the winches have not been serviced for some time (possibly ever - they are 5 years old). I can take all the parts off, clean them in mineral spirits etc, and relubricate where necessary but I would also like to remove this rust from the spindle (i.e. the inner "barrel" of the winch after removing the outer barrel).

 

[Onyva]

Hi bbg - I'm certainly no expert but I have used some acid that a french speaking, flemish living Greek friend gave to me so I don't know what type of acid it was in fact. All I know is that he said to make sure I diluted it (10-1) and then rinsed it off quickly. BUT, I used it on all things metal e.g. the propshaft, gori prop, rope cutter etc and it was brilliant. So much so that, long having run out of the stuff (and my mate is sadly no longer with us) I have just bought some acid from a DIY here in France that says it is for metals and I have used it again (this week in fact) on my propshaft and rope cutter. I haven't dare risk it on my prop yet given the comments above but will try it on an old prop (at home) first.

The only other bit of advice my greek friend gave me was not to use it ON the boat as it would burn a whole right through the deck, through the hull right through to the sea so I only ever use acid (whatever type it is) OFF the boat just in case. Not sure if that's of any help but bon chance.

 

[Adamastor]

If the spindle's bronze or the likes, Hydrochloric acid might work well- I know it works on brass for removing verdigris, and it's about the only thing to remove alinumnum oxide from spotty anodising. Normal swimming-pool acid diluted 50% is about right. If you want to apply it in situ you need to mix wallpaper-paste into it to thicken it, and remember to passivate it with bicarb when you rinse it off.

 

[awol]

I assume that as you call it "rust", the metal is ferrous. IMO your best bet is fine emery paper or even wet'ndry to remove the excess oxide (iron oxides have a greater volume than the original metal) and to smooth out the inevitable pitting. Sort of depends how bad the rust is.
OTOH if it's some other metal the "corrosion" may just be the remains of the grease congealed and dried - scrape off the crud and then get the Brasso out. If the spindle and drum are aluminium - buy some proper winches!

 

[bbg]

I don't really know what the spindle is made from. They are Harken ST16s, so I assume they are "proper" winches.

 

[Ubergeekian]

OK - then how do I get the rust off the winch spindle?

If you want to get rust off there is really only one option: you're going to have to remove it physically. Steel wool, emery paper, wire brush - the choice is yours, but if it doesn't involve sharp bits it's not going to work.

After you have done that you might want to convert the remaining rust to something more stable. Phosphoric acid (jenolite etc) converts it to black iron phosphate. I've been using POR-15 Metal Ready more recently, which converts it to zinc phosphate.

However, since it's going to live its live greased - I presume - none of that is really necessary. Get it nice and shiny with abrasive and slap on the grease. Done.

 

[Trundlebug]

Try using Cillit Bang, or even diet Coke. It's phosphoric acid and it cleans up stainless steel a treat.

It also has the double benefit of being useful for other cleaning applications, (so it doesn't end up being yet another specialist chemical with only one purpose, saves storage space) and also will remove the grime if it turns out not to be rust after all.

Best used with a pan scourer / scotchbrite pad material, it'll scrub it up a treat

Best of luck