Metal Cleaning Using Vinegar?

Sulphuric acid is still readily available. Just buy Oneshot drain cleaner.

Yes, no and maybe! Quick look at ebay:

• Lab grade (pure) Phosphoric Acid isn't what I call cheap!
• Dozens of useless Homeopathic "Phosphoric Acid" products.
• Hydroponic pH Control/Feed products that do contain a high proportion of Phosphoric Acid and are reasonably priced, hurrah! But I don't know what else is in them, so might be dirty or less effective than expected. However should be orders of magnitude better as a rust treatment than Coca Cola!
• Fertilizers that probably don't contain free Phosphoric Acid.
• Dental Etching products, a mix of Phosphoric Acid and Gum or Enamel. Pricey!

Anyone tried Bat Guano? If it doesn't work on rust, transfer to the kitchen. It's a taste improver...

Dave

I've heard it breeds a virus.

Thinking back to the days when I taught Chemistry, I recall that Oxalic Acid is Poisonous.

I advise caution.

.

The idea of putting a crusty part in a tub of something, and removing it a couple of days later when it's clean is way more appealing to me than using abrasives, wire wheels, power tools, elbow grease and time. I would prefer to use those on things that can't be done any other way.

I've had a Dremel for years and I don't think I've ever used it without thinking what a piece of junk it is, and that there must be a better option.

When dealing with many finishes even when they are not poisonous I tend to wear protective gloves not just to prevent any reactions but also to keep my hands clean especially with wood stains. I know that I also need eye protection and possibly a mask of some description depending on what I am using.

Why on earth would you need Lab grade pure phosphoric acid for ourk purposes ,ie removing rust or anodising. 5L of 30% phosphoric acid is available for £16-50 delivered and will dilute to 15 L and last most of us years .

Jenolite was / is a old name in rust removal and is  just dilute Phosphoric acid. 

I used a hot bath of the stuff some tears ago to treat rusty bits of a motorcycle I was restoring.  Things like the chain tensioner and some specialised but unobtainable nuts and bolts. After a few minutes they came out totally rust free and were rinsed , dried and painted with some silver paint ( nearest modern equivalent is Rustoleum) never rushed again in the years I owned it. 

Bat Gunano ?

Edited By Engine Doctor ( Phil ) on 19/02/2022 17:17:52

Is car alloy wheel cleaner (the stuff in the hand sprayer bottles) based on phosphoric acid? It has a similar smell as rust remover.

Yeah, that's my point: you don't need Lab grade Phosphoric Acid to treat rust! Earlier in the thread I questioned the interest in removing rust with home-made concoctions when commercial products like Jenolite are available. I recommend using them!

Bat Guano is a joke aimed at homespun experimenters. It's effective somewhere between Vinegar and fruit juice as a rust remover, so why not give rodent poo a go if you believe in that kind of thing?

Phosphoric Acid is effective, but buying the right stuff for a DIY rust potion needs a little care. There's not enough of it in Coca Cola or Homeopathic products while Food, Lab and Dental Grade acid is expensive.

Dave

acid on amzon

Alli wheel or lorry body cleaner is I believe lactic acid ! 10% phosphoric acid will work and as ferrous phosphate is insoluable in clean water will leave a protective coating. Methods that leave a chemically clean surface will start corroding INSTANLY ! I once watched a sandblasted cylinder head turn red in 20 mins.

Any strong acids in untrained hands are VERY dangerous ! Even diluting them is dangerous due to the exothermic reaction that will take place ! Noel.

In the States we have naval jelly, which is phosphoric acid. I see Loctite still makes it, but I'll bet only old timers have heard of it. "If it rusts, throw it away and buy a new one" is the thinking.

While restoring a bike I had five identical rusty nuts taken off a sprocket carrier so decided to do a little experiment. Keeping one nut back as a control item I tried 4 different acid solutions overnight in an unheated garage to see what the comparative results where.

The picture below shows the control item at the front and from left to right:

• 14% sulphuric acid solution;
• Gateros acid salts made to recommended solution strength;
• White vinegar (5% acetic acid); and
• Citric acid crystals made up to 3 heap teaspoons in 200ml aprox water.

The results show that the vinegar was the least effective with the sulphuric not much better. (As a side note sulphuric acid tends to be more reactive with organic materials than metals compared to hydrochloric acid. Harpic toilet cleaner contains hydrochloric acid and can be used as a mild metal cleaner.) The Gateros product left a dark tarnish.

The clear winner was citric acid. It was also the cheapest, costing £5.39 for a kilo from eBay.

As all four products reduced the rust there were no losers and leaving the nuts to soak for longer or in a warmer environment would also have improved the results.

That's useful, Graham.

I've been using citric acid, and the only downside is the thick sludge on really rusty items. The things I have derusted have finished matt black.

The 'patina' on the gateros one may be iron phosphate, which I tend to think is a 'good thing'.

Neil

Graham, purely on a note of safety, they look like nyloc nuts and as such should not be reused ! Noel.

You're right Noel. They were destined for the bin anyway so I thought I'd just experiment on them on their way there.

Do they?

And most homeworkshop jobs will allow a nyloc to be reused several times before it becomes loose enough to be just a plain nut. If you can't turn it by hand, the nylon insert is still doing something.

Graham, thanks for bringing some facts to the table.

A few years ago all the discussion seemed to be about the more 'passive' solutions for removing rust. I think even MEW did a piece on 'evaporust' telling us it was pretty good. Now, not a mention of such things.

I personally have used a lot of citric acid, it works but tends to etch the steel leaving it a bit dull. It can also produce some dreadful bad egg type smells if left too long doesn't go down well in the house, as you can imagine

For these reasons I also tried Arc's rust remover product which I imagine works in a similar way to 'evaporust'. It was totally hopeless. If you just let the parts soak in it for 24 hours nothing at all happened. If one followed the instructions and repeatedly scrubbed the part during the soak, one would eventually remove the rust. But after a few hours of this scrubbing nonsense one cant help thinking that it would have been a lot less mess to have got the rotary wire brushes and the flapper wheels out in the first place.

Gerry

I always use phosphoric acid from E bay, works well on badly rusted stuff, if heated. Despite Dave's inability to select the stuff on Ebay, most folk will find the 30 to 50% phosphoric acid without much trouble. It is a lot cheaper than the commercial de-rusting agents that are phosphoric acid based that Dave seems to recommend.

For metal that is not rusted too much, washing soda and a battery charger works wonders.

Andrew.

Arc sell Restore

I used restore on lot of tools that were rusted solid. I diluted the concentrate the recommended amount and used it in a heated ultrasonic bath.

The results were the opposite of Mr. Maddens!

One of the things was a radius gauge set - after some time in the bath, the individual leaves can move separately.

I don't know what components are in Restore - and guess that Shield Technology will NOT be keen to divulge that information! But the SDS may provide a clue!

MC