Metal De-Corroder and its effects

[RDGAC]

Howdy all; forum's been a bit quiet of late on the gun front, but I have here a technical question which is puzzling me a bit.

Firstly, some background. Recently I persuaded my boss to cut loose on the string and buy some Renaissance Metal De-Corroder (please read the information therewith before responding), a handy little compound which seems to be very effective in killing rust without killing your object in the process and rather less deleterious to its appearance than wire wool. Full of cautious enthusiasm I set to work with this stuff on one of our swords. This particular sword was in a dire state; it had sat in its scabbard for something like 15 years, and the centre of the blade was one solid cloud of rust for about half the total length of the blade. It was a sorry thing, and I held out little hope of improving its lot in life. This was made especially sad by the fact that this particular blade was visible a fine example, inscribed with (just about visible) battle honours one one side and what turned out to be the 4th Dragoon Guards' regimental emblem on the other.

(And yes, I realise this is a European weapon - bear with me, neh? )

So I went to work. Ideally one should simply immerse the affected metal in the solution, but being run on a shoestring we neither have, nor can afford, a tank of such a capacity (let alone the volume of solution to fill it), making it necessary for me to paint the solution onto the sword. This obviously necessitates constantly re-applying a thin layer to the metal, as well as accepting much greater evaporative losses. But still, it couldn't hurt, frankly. The photos included show a view of the untreated blade; all that brown gunk is rust. It wasn't at all pretty.

The results, therefore, surpassed all my expectations. As you can plainly see if the post-treatment pictures (the more normally-proportioned ones), the sword is one more legible, the text almost unmarred by more than a decade (at least) of neglect. All in all I was very, very happy - and extremely glad I'd bought that superb product. End of intro; more in post 2.

[RDGAC]

Now, on to the Ethnographic bit! As you may be aware (dear reader) we have in our museum a jezail, with what looks like a watered barrel. "Aha", says I - "a prime candidate for de-rusting. It's a melancholy thought, that no-one shall again see the beautiful metalwork hidden beneath the mottled ugliness of rust, bearing witness to (inadvertent) neglect stretching over years." But wait - how will this stuff affect the very steel I seek to preserve, the wonderfully patterned wootz (or Damascus, or whatever it is - I'm still not wholly clear on this point)? Full of my increasingly typical circumspection, I rang up the chaps at Picreator and was told that it should be fine - Renaissance Metal De-Corroder shouldn't affect sound steel unless you leave said steel in the fluid for about a month or two, at which point you're just asking for trouble. Deciding that this would do, I filled a mug with the solution, rested the (clamped-up) barrel's breech end therein, and went home, fretting. I had already treated the hammer, trigger, trigger spindle and two of the barrel bands, with good results - but I still worried about that pattern.

The end result of this has been... interesting. What's undeniable is that the solution has removed a whole bunch of corrosion. It's not just removed it - it's devoured it. Sections of metal that haven't seen the light of day for decades are once more staring happily at me. Huzzah! But all the same, I'm a tad concerned. As you can see in the photographs, there is a clear boundary layer between the treated and untreated areas of steel. Treated steel seems to lose at least some of its lustre; it becomes very, very clean, but doesn't seem to shine as it once did. In addition, the area around the breech plug now has patches of orange colour, which I assume to be copper. This I find mystifying and more than a little worrying. I'm additionally not sure whether the solution has affected the watering, simply because - surprise, surprise - it was buried under rust heretofore.

Included are pictures. Note difference in colour and patina between the hammer and its lock; the clearly defined layers between different sections; and the strange deposits towards the very back of the barrel. Any ideas as to what they are, what the effect of this stuff on the watering might be, and what's making the steel so grey and lifeless (if very, very clean)?

[Atlantia]

Hi,

Sounds like your rust eater is a somewhat acidic product. This is not umcommon of course, and most rust removers are by nature highly corrosive.
The results on the sword blade looks quite good in the pictures.
The results on the gun parts are perhaps not quite as desirable.
Thing is, oxidisation goes through several stages, and having some stable oxidisation in pits is sometimes more desirable than 'cleaning' those pits out.
On an old steel/iron surface, what can look like a mottled dark shiny 'patina' (not rusty and flaky just dark and obviously slightly oxidised), will often be hiding a multitude of small, tiny and microscopic corroded imperfections which will all be revealed if using a corrosive solution to eat the oxidisation out of them.
even an undamaged polished steel surface can be affected by the acid and mildly etched. Which can leave a grey looking colour.
Of course it all depends on the type of steel/iron, how its treated with the etching solution etc.
Try some tests with scrap pieces of ferrous metals.

One thing to remember is that there is no 'magic bullet' for cleaning up a neglected piece of rusty metal.
Slow is best, as removing patina is much easier than restoring it.
If a piece is pitted, then a decision has to be made as to if the oxidisation is to be totally removed, stabilised, left alone, repolished etc, etc.
Total removal might make a piece look 'sandblasted', repolishing might make it look new.....
The two 'best' solutions are often:
Stabilise and conserve, removing loose flakes but essentially leave 'as is'.
Or partial removal of oxidisation (down to or close to the level of the surface) while preserving the dark stable oxidisation in the small pits so as to maintain a 'natural' flat shiny surface (even if it is mottled).
So perhaps a wipe over with your solution to start to remove the loose, surface stuff, then neutralise and repeat if needed.
Never a good idea to treat a piece with different techniques in sections as you might get very different results. Or worse, you might get 'rings' where the top of the liquid level was.

[Rick]

I have used the stuff ; so far only on monosteel .
I noticed the effect you mention .
Some pretty crusty stuff was on this kukri .

I just applied with a brush to the affected areas .

[RDGAC]

Interesting to hear that, Rick; I've found that the stuff dries out far too quickly, when applied with a brush. Ten, maybe fifteen minutes between coats are the maximum I can get. Even at the end of that the solvent has almost entirely evaporated.

Atlantia: Yes, it's acidic. It's not too acidic, which seems to be its chief selling point; it's generally much gentler than your average acid when it comes to getting rid of corrosion, so much so that you can handle it without gloves.

The plan with this barrel is, as it stands, just to try and remove the heavy mottled rust present all over its length. I realise that it may prove to be even more unsightly if it is removed, only to leave behind deep pitting and unevenness upon the barrel surface, which is the main reason I'm proceeding cautiously. The loose stuff has already been removed; it took me nearly two months to get rid of it, in fact, the old-fashioned way. The breech end seemed a reasonably sensible test area since it's heavily rusted and the small areas visible indicate that it's lightly grained; those areas which have been shielded from moisture, further up the barrel, show off a very attractive watered pattern and thus I didn't want to ruin them inadvertently.

I have found that careful, light use of the Renaissance product called "Pre-Lim" can help restore the sheen of the metal, but since it's still abrasive (even if it's a very gentle abrasive) I'm not sure if I'd be happy using it on the watered barrel.Perhaps I'm just underestimating the durability of the pattern itself.

[Tim Simmons]

If the surface is badly rusted and removal has left a heavy etched surface then repolish and get a steel blackening chemical to restore the visual appeal. You could get advice from a "gunsmith" sporting shotgun maker, they must do lots of refurbishing jobs.

[Rick]

Originally Posted by RDGAC

Interesting to hear that, Rick; I've found that the stuff dries out far too quickly, when applied with a brush. Ten, maybe fifteen minutes between coats are the maximum I can get. Even at the end of that the solvent has almost entirely evaporated.

Atlantia: Yes, it's acidic. It's not too acidic, which seems to be its chief selling point; it's generally much gentler than your average acid when it comes to getting rid of corrosion, so much so that you can handle it without gloves.

The plan with this barrel is, as it stands, just to try and remove the heavy mottled rust present all over its length. I realise that it may prove to be even more unsightly if it is removed, only to leave behind deep pitting and unevenness upon the barrel surface, which is the main reason I'm proceeding cautiously. The loose stuff has already been removed; it took me nearly two months to get rid of it, in fact, the old-fashioned way. The breech end seemed a reasonably sensible test area since it's heavily rusted and the small areas visible indicate that it's lightly grained; those areas which have been shielded from moisture, further up the barrel, show off a very attractive watered pattern and thus I didn't want to ruin them inadvertently.

I have found that careful, light use of the Renaissance product called "Pre-Lim" can help restore the sheen of the metal, but since it's still abrasive (even if it's a very gentle abrasive) I'm not sure if I'd be happy using it on the watered barrel.Perhaps I'm just underestimating the durability of the pattern itself.

Yes, I had to refresh the areas about that often; a little picking and scrubbing then reapply .

I'm wondering if your barrel might benefit from a prolonged soak in Pineapple juice .

[Dmitry]

I bought a sample bottle of this stuff, and used it on a worthless blade. It removed the rust, and etched the steel to a dull, lifeless color, like the percussion cock and barrel on the photos above.
I put it away, and haven't used it again.

[Battara]

There is a difference between patina and rust. I would use this stuff sparingly and take off the rust but not the patina.

As far as the copper is concerned, make sure that what is in the solution is not copper or brass - the acid with steel probably creates an electrolysis with copper or brass, making the copper ions to migrate onto the steel, a natural result with many acid solutions.

Finally, I would suggest polishing and then adding a patina to the "lack luster" surfaces.

[Ian Knight]

I have used this product on a few swords but use with caution. I too was shocked the first time that I used it. It leaves a horrible dull grey surface.
Be prepared to do a bit of polishing after treatment. I use very fine carborundum paper, used wet, and then polish with Solvo.
I wouldn't use on a sword with faint etching because the polishing will wear it further. Neither would I use it on any sword with blueing or gilding. On a plain blade it is fine but go carefully with the treatment. I apply the liquid with a brush, leave for half an hour and then wash in water using a brass brush on the rusted areas. Repeat if required.
I don't like seeing rust on any sword because it is damaging the metal underneath. Black patches also harbour red rust underneath so it isn't safe to leave that on the metal either.

I contacted the makers of De-corroder a year ago regarding the effect their product had on metal. Surprisingly the were quite taken aback and told me to stop using it.

Ian

[RSWORD]

An important step in all of this process to definitely not forget is to add plenty of oil after any form of etching, polishing or anything of the sort. I recommend WD-40 as the first coat after a good polish or etch as it does a great job of expelling water molecules from the steel and really sinks into the pores of the metal. After a day or two of a good WD-40 soak, wipe away, clean area with acetone and then apply a light coat of gun oil to the area to conserve for longer periods of time.

[Ian Knight]

I would personally recommend applying Renaissance Wax which is used by many museums to protect valuable objects.

Ian

[RDGAC]

I've bee steadily working my way through our collection, applying Renaissance Wax to the hard surfaced objects where it seemed appropriate, and the results are indeed good. It's a very highly regarded product, not least because the coating it gives is both attractive and durable. I'm still unwilling to use it on leather, despite being informed that it's safe to do so, but it's excellent for metal and wood, from what I can gather.

The etching of the metal is indeed troubling. The sword displayed in the first picture was treated with Pre-Lim polish after being treated with the de-corroder, which may go some way to explaining its better finish than the tested area of the jezail barrel, but I remain cautious. Perhaps, if I am to use this at all, I shall have to apply it to each spot of rust individually (which will mean taking about 6 months to get it off); or perhaps there's just nothing more to be done for this barrel, much as I'm very sad to admit it.

[Rick]

Pineapple Juice ??

[RDGAC]

Pineapple juice? I'm lost.

[Rick]

A very gentle way to remove rust .
Immerse and brush daily, then put it back in to soak .

Keris collector's standby .

[Battara]

You know if you use pure sulfuric acid it will just eat all that rust away, along with any steel, brass, silver, horn, etc.

[RDGAC]

That would certainly cut the Gordian knot; one is reminded of the Ameglian Major Cow from The Hitch-Hiker's Guide to the Galaxy: "I know many vegetables that are very clear on that point, sir; which is why it was decided to cut through the whole tangled problem by creating an animal which wanted to be eaten, and was capable of saying so clearly and distinctly. And here I am! (Baah.)"

[RDGAC]

In another classic exercise in Thread Necromancy, I've begun working with this stuff again after a considerable hiatus. Will have some photos to show soon; at present I'm conducting experiments. Watch this space

- Meredydd

[RDGAC]

I've returned to trying this stuff out on my much-prized, Damascus, rifled barrel, from the Khyber Pass jezail we acquired last year. The results are interesting.

Using RMDC demands a heck of a lot of attention - in stark contrast to the glib promises on the bottle, one is not "freed" from the process, simply because (unless one knows precisely what metal one is working with) one has to keep checking on the effect it's having on the object upon which it is used. This is especially so in this case, because of the importance of preserving the pattern on the barrel.

I have selected three specific areas upon which to experiment. One is a large, deep blister formation of corrosion; the other, a section of approximately 1.25 inches, which has been subjected to the formation of small, shallow patches of mottled corrosion. In both cases, a visible pattern remains in the area surrounding the corrosion, and presumably is also present beneath them. The third area, which was given one exposure of approx. 4 minutes, lay between these two; it consisted almost wholly of sound, patterned steel, which appeared unaffected.

In using RMDC I have adopted a seven-step process, viz.:

1) Apply a small amount of RMDC, using a fine-tipped paintbrush, to the relevant areas.

2) Leave the solution to work for between 4 and 8 minutes, with duration increasing if the sound metal appears undamaged.

3) Rinse away solution and dry exposed area/s.

4) Gently rub area/s with dry cloth.

5) Gently card area/s with small brass brush.

6) Probe any corroded areas with steel pick, being careful to avoid exposing sound metal. If sound metal is exposed, immediately stop.

7) Clean away any residues and return to step 1.

Thus far, I can report that:

1) RMDC still eats rust. (Not exactly surprising.)

2) The resultant finish is, at best, a tad dull.

3) The solution does not as yet appear to have any permanent effect on the pattern on the barrel. Though the metal is faded and dulled (indeed, pretty much matte), the pattern is still visible, if not prominently.

4) Prolonged application does not appear to produce desirable effects; especially when used on older and/or softer steels, it is important to keep a very, very close eye on things.

5) Polishing may yield an improvement in finish, but may also adversely affect the patterning. Thus far, experimental use of Renaissance Pre-Lim polish has not noticeably affected the pattern, but has also not noticeably improved the overall finish - a 0-0 draw!

6) The dull, matte-finished metal has properties I did not expect; to be exact, it appears to be slightly soft, and can be burnished to an extent by polishing. Passing a brass brush over the metal appeared to yield some scratching, unexpected given that the metal is still steel.

More to come. Meantime, some piccies.

[Ibrahiim al Balooshi]

Originally Posted by RSWORD

An important step in all of this process to definitely not forget is to add plenty of oil after any form of etching, polishing or anything of the sort. I recommend WD-40 as the first coat after a good polish or etch as it does a great job of expelling water molecules from the steel and really sinks into the pores of the metal. After a day or two of a good WD-40 soak, wipe away, clean area with acetone and then apply a light coat of gun oil to the area to conserve for longer periods of time.

Salaams, For treating rust spots I use aluminium foil ... same as for using sandpaper ... it works at sub atomic levels apparently and the rust does vanish slowly. Use with just fingers and a few foil pieces folded in half... like a small wad.... and rub away. I get the same grey horrible result using lemon salt but the patina is coming back using olive oil and or gun oil . ( sewing machine oil )

[josh stout]

I have been working on a technique with decent results. First I wash the blade with soap and water using a plastic pot scrubber. This is to partially degrease and partially to remove any easily removed rust. Then I degrease with Windex following with a vinegar soak. This gives similar results to the product you are using. After that there is still some patina, the rust is almost entirely gone, and pattern welding shows with high carbon steel darker than the softer parts. The problem is the graying you have mentioned. So I polish the blade with 6000 grit micromesh (http://micro-surface.com/index.php?main_page=page&id=15). The micromesh gently brightens the gray areas without completely obscuring the pattern brought out by the acid.

Josh

[rand]

I have heard that the Met uses kerosene and sawdust in a slow turning barrel to clean mail.

Am very glad you posted these before and after photo's. Am interested in the renaissance liquid decorroder for cleaning mail. From the photo's that does not seem like the best approach because of the dull finish.

rand

[Ibrahiim al Balooshi]

The weird and wonderful cleaning agents and solutions for restoring and preserving ethnographic arms and Armour is a subject perhaps best placed in the margins of Forum activity ...and I respectfully request its placement in Miscellaneous ( Ethnographic Miscellania ) for concise referencing by members..

I suspect this form of aggressive rust remover will tear a good sword apart removing patina and sword blade at the same time. I find it reasonable to know the less dangerous chemicals and apply them first such as light cleaning with warm soapy water...then step up to cold coke cola... but to check every 8 to12 hours removing with soapy water and rinse at the first sign of action. The juices come next and any fruit juice will do ...Then comes the paste with Tomato being quite good...again check every 12 hours... etc The worst stuff is acid... and even worse than that hot solutions ... Hot acid will destroy your item if left too long ...and check every half minute ... its that fast...Dont use it is my advice. I put this de corrosion stuff in the same category...

The action suggested at #22 by Josh Stout is excellent...

[mariusgmioc]

Hello and forgive my late reply as I was very busy with work lately!

I have been using Ren. Met. Decorroder for years and I can confirm it is an excellent product. It is absolutely safe for healthy metal and much better than any alternatives suggested here.

For example pineapple juice that was recommended by some, is quite effective but it is acidic. Moreover, the acidity and thus, aggresivity depends on the brand used. Coca-cola is even more acidic than pineapple juice and definitely less effective than Ren. Met. Decorroder.

Yes, Ren. Met. Decorroder removes etching because etching IS a form of corrosion. Practically etching is a controlled and selective corrosion of certain areas of the metal surface. It's just that the oxidation is not brown and flaky like rust is but dark grey and in the form of a thin film that covers just some areas of the metal.

So after treating either Wootz Damascus or Pattern Welded Damascus with Decorroder, it must definitely be re-etched to get back its patterning.

The dull grey patination that remains after the treatment with Ren. Met. Decorroder is easily removed with Pre-lim or any other very gentle polish. However, the dull grey patination has a protective role as it prevents the formation of rust for several weeks, so if you decide to remove it, you should apply some kind of protection to the metal immediately afterwards (I normally use Ren. Wax and rarely, mineral oil).

And I tried Ren. Wax on leather with great results. I assume that can also be used as shoe polish, but it will be probably the most expensive shoe polish on the market.