Metal De-Corroder and its effects

[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