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Metal de-coroder

Anyone had experience of this product

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Plasma22/06/2019 10:23:33
387 forum posts
45 photos

Hi all,

I've been looking around at renovation products for use at Wentworth and came across the stable mates of Renaissance wax polish. One of which is metal de-coroder liquid.

It is for ferrous and some non ferrous metals and is safe to use.

Initial results are pretty encouraging based on some simple tests.

Just wondered if anyone had used this stuff before.


Mild steel plate and a well rusted drawer lock after a couple of hours dipping in a solution of the product.

Regards Mick

pgk pgk22/06/2019 10:55:41
1721 forum posts
287 photos

Looks like some good derust products about.

2 relevent search links re rennaisance:

data sheet pdf

Wikepedia re active priniciple

An interesting vid here using wd40 rust remover wd40 rust remover

Speedy Builder522/06/2019 11:00:55
1981 forum posts
139 photos

Very French !! de-coroder , English de-corRoder

Phil Whitley22/06/2019 11:05:57
1146 forum posts
145 photos

I use home brewed cider vinegar, and it is VERY effective, and free, and doent seem to attack the base metal. I have managed to save things that I had really written off due to rust, like some old thread guages, which are now like new, apart from some pitting where the rust had gone deep, but prefectly readable engraving on them, which was invisible before. Electrolysis in a bath of washing soda is also good, but gives off hydrogen, so beware of flammability. Some people also use white vinegar, or vinegar and salt.

Plasma22/06/2019 11:13:46
387 forum posts
45 photos

That chuck refurb is a pretty amazing piece of work! There is hope for a lot of scrap out there lol.


Barrie Lever22/06/2019 11:27:20
462 forum posts
38 photos


Looks good, I have used alloy wheel cleaneer to do similar but your gear looks better to me, I will get some of that and hold in reserve.



Bazyle22/06/2019 12:00:01
5131 forum posts
199 photos

So the whole bottle in top picture is equivalent to a couple of lemons.

The cider one is a good idea. Who doesn't have a few apple cores and rotten ones in the autumn. Dump in a plastic container with a little water, leave open to air to ferment, then it will oxidise to vinegar. A few years ago I was filling the wheelbarrow with windfalls, mostly bird pecked and rotting, when a downpour drove me inside. Next day the galvanising was stripped up to the water line.

Salt only helps further the rusting after treatment if not washed off. Its use comes from the old grandmother's use in cleaning teas stains off china where it is just a super mild abrasive that quickly disperses. It has zero chemical contribution.

At the end of the day phosphoric acid is by far the best for low cost and leaving a slight layer of phosphate for on-going protection.

Kiwi Bloke22/06/2019 12:21:54
398 forum posts
1 photos

There's a lot about de-rusting on this forum, and others. Some is true, some isn't. Some is frankly magical beliefs.

Although vinegar and dilute citric acid have been advocated - both certainly work - some users report etching of the base metal under certain conditions. Phosphoric acid will certainly attack - especially if used in a high enough concentration to please the impatient. My experience is that the phosphate coat is too fragile to be worth the risk. Electrolysis is probably the ideal, although some warn of the risk of hydrogen embrittlement.

Molasses, improbable though it sounds, really works - albeit slowly - with no risk of attacking the base metal - and it tastes good! It acts by chelation, not acid attack. Other chelators work, but can't be easier to obtain than molasses. Tubs of the stuff can be got from country stores servicing the horsey brigade. I presume it goes into the front end of a horse, but what for I don't know (de-rusting?). Evaporust is believed to be a commercial (ie expensive) chelator. That works very well too.

Scrape crud off first, and de-grease with a strong detergent wash, then into the molasses (all sorts of dilutions are suggested; I use about 1 molasses : 2 water - or not - it's not critical. Leave, fully submerged, for a few days (longer if thick rust) and gently scrub off the grey residual coating. Rinse and repeat, if needed. When all done, oil immediately.

It's all been said before, but the message clearly hasn't got out...

Plasma22/06/2019 13:30:27
387 forum posts
45 photos

This stuff is used by museums to restore old metal so it is safe to use on delicate items they wouldn't be happy dunking in a tank of vinegar, lemon juice or molasses. laugh

It is concentrated so diluted in water for normal use, the small sample bottle will still go a fair way.

I've written to WD40 to ask why we cant get hold of their rust soak liquid over here just as an aside.

Best regards Mick

Kiwi Bloke24/06/2019 00:15:32
398 forum posts
1 photos

I don't want to flog a dead horse, but I can't think of any reason not to use molasses, except impatience...

Bazyle24/06/2019 00:43:51
5131 forum posts
199 photos

Because it stinks? We have been using molasses in the men's shed but moved it to the store shed. On advice from a member who had been using it for some time and carefully experimenting we used his suggestion for dilution which he had found to be significant. I don' t know the detailed chemical composition of molasses but I suspect its action is actually fermentation (it is basically raw sugar) to alcohol then oxidation to acid. The slow reactions make it gentle and unlikely to over react.
We also used electrolysis in the shed but before we got the fridge and burglar alarm were turning the electricity off when not there so it was rather slow.

Kiwi Bloke24/06/2019 06:40:43
398 forum posts
1 photos

No. Fresh molasses smells like molasses. Not to everyone's tastes, perhaps, but not a stink. If it is kept clean and not contaminated by microbes, a 'working' mixture won't start fermenting, and will stay molasses-smelling for weeks. Once the bugs get in, however, it can grow a disgusting crust and will stink. Presumably, alcohol may be produced by yeasts, and this may then oxidise to acetic acid, etc., and all sorts of other smelly products of microbial metabolism may be produced. Whether these also remove rust I don't know, but it's irrelevant. By the time it's offensive, anyone with any sensitivity would have slung the stinking mess away (and you don't need to worry about disposal methods). The important point is that fresh molasses removes rust, and it is by chelation. This process does not cause the base metal to be etched. The chelator EDTA also removes rust. Evaporust also works well, and is believed to be a chelator. It ain't magic or mystery.

pgk pgk24/06/2019 07:03:18
1721 forum posts
287 photos

I've seen vids of molasses being used and don't argue with the fact it works. However the claims of chelation need explanation. The only chelation i was taught about was for the treatment for heavy metal poisonings.. specifically lead with calcium versenate. I kept emergency stuff in stock for decades but never saw a lead poisoning case so never got to use it.
As I understand chelation it's the grabbing of metal ions and binding them to the substrate. That should depend on the metal being soluble to be in an ionic form and iron oxides aren't so (to my understanding) the molasses would first have to change the oxide to something else as a chemical reaction i.e not chelation.

Checking on google, molasses has a pH between 5-7 so it's essentially an organic acid....which may/may not soecifically bidn to the oxide rater that clean iron with 'chelation' being used to give it magical properties


Kiwi Bloke25/06/2019 02:50:25
398 forum posts
1 photos

Apologies to disinterested readers to appear to be flogging a dead horse...

Well, I don't know how chelation works at an atomic level, but it does appear to prefer to bind iron from the oxide than from the lump of the element. Probably something to do with the relative strength of inter-atomic bonds at the surface of the different material surfaces, etc., etc.. One thing I'm certain of, however, is that, at each higher level of scientific training, what one learned at a lower level is shown to be a lie. Now, it's all quantum-effects. Uncertainty rules!

Two perhaps pointlessly pedantic points: (1) '...the molasses would first have to change the oxide to something else as a chemical reaction i.e not chelation'; chelation is a chemical reaction, not a physical change. Perhaps you didn't mean to imply that. (2) A strong reduction reaction can reduce rust, with no ions in solution being involved - think thermit. But, of course, that's rather different from reactions in solution.

Evaporust info. pages discuss its function via chelation.

pgk pgk25/06/2019 07:31:07
1721 forum posts
287 photos

..if you want to be pedantic..
My objection is against the word 'chelation'. By using that uncommon word there is a sub-text of some unusual (almost magical) property ascribed to the process. My understanding of chelation is the removal and binding of heavy metal ions to another molecule which in medical terms then allows it's excretion and removal. That requires the heavy metal to be in an ionic form and then part of a new complex molecule.
I was simple stating that for iron in iron oxide to become ionic it first has to react with acids in the molasses and change to a soluble compound which may/may not then 'chelate' by becoming part of a greater complex. I suggest that the word is being misappropriated for the sake of sales promotion.
I agree that the stuff works.'

Kiwi Bloke25/06/2019 11:15:45
398 forum posts
1 photos

Poor old dead horse - the flogging continues...

The problem with parcipitating in this forum is that it's too interesting, and it becomes difficult to resist being drawn into discussion. It's also fun to be provoked into finding out more about things.

Chelation seems to be commonly (usually?) discussed in applications where its purpose is to sequester metallic ions from (aqueous) solutions. Does the metal have to be ionized, in solution? Why do (some?) chelators act preferentially on iron III oxide, rather than the bulk metal? Is the presence of an acid also necessary to promote dissociation (oxalic acid and citric acid are also chelators)? I don't know the answers - it's decades since I was taught chemistry, only touched on chelation, and poking about the 'net to try to find the answers only confuses me...

However, from Wikipedia's Iron (III) oxide page: ' Iron(III) oxide is insoluble in water but dissolves readily in strong acid, e.g. hydrochloric and sulfuric acids. It also dissolves well in solutions of chelating agents such as EDTA and oxalic acid.' [ my italics ] Unfortunately, the whys and wherefores are not provided. Tantalizing.

The point is that molasses and other chelators do not act by indiscriminately making inorganic salts from both the oxide and the metal as acids do. Clearly, it's magic.

Any chemists out there who could enlighten? At least two of us would like to know...

SillyOldDuffer25/06/2019 12:28:58
5607 forum posts
1153 photos
Posted by Kiwi Bloke 1 on 25/06/2019 11:15:45:

Poor old dead horse - the flogging continues...

The problem with parcipitating in this forum is that it's too interesting, and it becomes difficult to resist being drawn into discussion. It's also fun to be provoked into finding out more about things.


The point is that molasses and other chelators do not act by indiscriminately making inorganic salts from both the oxide and the metal as acids do. Clearly, it's magic.

Any chemists out there who could enlighten? At least two of us would like to know...

Three maybe!

Decades since I did Chemistry and as usual I wasn't paying attention. As a result "Any sufficiently advanced technology is indistinguishable from magic."

In my simple understanding there are two types of chemical bond. Ionic bonds consist of positive and negative ions sticking together like magnets, except the bond is electrostatic. Covalent bonds are more subtle - they form when atoms share orbiting electrons. Of course my understanding is a simplification only one small step up from noticing that some 'stuff' reacts with other 'stuff' and generalising a few rules.

The common feature of bonds is that atoms interact with other atoms to form stable, rather than unstable, combinations. Pauling got the Nobel Prize for his work on 'The Nature of the Chemical Bond'. His understanding gets well into the 'Several Electronic Configurations' that attract atoms together, not just two. Chelation seems to be a species of covalent configuration but talk of Wave Equations and Resonance leaves me in the dust.

Renaissance liquid looks to be a concoction of a mild acid, something like Vinegar, Citric or Oxalic, plus a chelating agent. It's probably been formulated to be more effective than simple acids alone and less messy than Molasses. The acid breaks the rust up and the chelating agent gobbles the residue, fast, clean and unlikely to damage metal. How it works at the electronic level is quantum chemistry, completely out of my league.

Ignorance is bliss!


Plasma25/06/2019 13:31:14
387 forum posts
45 photos

I only asked if anyone had used it!

Anyway, molasses, vinegar, apples, lemons, magic and atomic chemistry aside... it works. That's all that matters to me.

By the by, WD40 got back to me and said the magic rust soak was only available in America at present, would not be drawn on future possibility of it being available here. Must be tariffs, trade agreements and euro regulation or some such.

Regards Mick

Kiwi Bloke26/06/2019 07:49:59
398 forum posts
1 photos

'I only asked if anyone had used it!' Now look what you've started! Where's Michael Gilligan when you want him? Link to enlightenment required! cheeky

Edited By Kiwi Bloke 1 on 26/06/2019 07:53:15

pgk pgk26/06/2019 09:20:47
1721 forum posts
287 photos

The obvious conclusion here is that one should coat one's car in black treacle and let the rain protect it from rustdevil

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