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-   -   How to clean rust over gold or silver (http://www.vikingsword.com/vb/showthread.php?t=23039)

Kubur 25th August 2017 07:04 PM

How to clean rust over gold or silver
 
Hi Guys

I need some help for this long week-end.
How to clean a hilt or a blade with rust over silver or gold decoration without removing everything?
Especially when the rust is thick...
Thanks!!!!

Kubur

shayde78 25th August 2017 07:58 PM

PLEASE, PLEASE, PLEASE wait for more knowledgeable responses before you try this method, but I have had some luck with wrapping aluminum foil around an eraser and gently rubbing away the oxidation. Using oil would reduce friction further, and serve to protect the underlying precious metal.

Again, I offer this as a suggestion, but wait until someone with actual conservation experience endorses it, or offers something far more sophisticated. I would hate to see you ruin your piece.

mariusgmioc 25th August 2017 08:52 PM

Cleaning a rusted damascened piece is a very tricky task.

For very little rust over gold koftgari, I used Picreator's Metal Decorroder, then gently wiped off the rust. I managed to leave most of the koftgari in place but there were some losses.

For a more heavily corroded piece, it might be a completely diferent story and I would like to know the answer myself. :shrug:

PS: What about some electric rust removal?!

Kmaddock 26th August 2017 06:57 AM

Hi Kubur

I have reclaimed a good few rusty blades and guns

Below are my experiences, personal opinions and maybe the methods might suit your job

I am aiming for rust free but not polished in all my cleaning, I suppose knowing what you want as an end result is the first question you need to ask yourself.

I have used electrolysis on some bayonets.
It works great but the platina is gone and the metal turns a very grey colour and totally lifeless, my bayonet turned a zinc like colour. looking at the amount of bubbling I think if there was any rust under the gold the gold would come off.

With the Picreators metal de coroner the rust is removed but again the steel looses its platina and takes a grey look, I tried this on an English etched cavilary sabre and did not like the end look of lifeless steel but the rust was gone.

My most successful method is soaking in diesel for a few days then gently polishing with oooo bronze wool, and repeating the soaking in diesel over the week or two With cleaning in between, Messy work and not suitable for in the kitchen. I recommend nitrile gloves and a bench you do not care too much for. With some metals a redish hue can develop on the steel but v careful oooo wire wool will remove this.

I have a scissors katar, search my posts from a few months ago and you will see my cleaning, you can see the silver on the metal work which was completely hidden by rust and was exposed by my cleaning, not a beautiful end result but this is what I go for in my cleaning.

Best of luck.

Ken

Philip 26th August 2017 07:27 AM

Quote:
Originally Posted by mariusgmioc
Cleaning a rusted damascened piece is a very tricky task.

For very little rust over gold koftgari, I used Picreator's Metal Decorroder, then gently wiped off the rust. I managed to leave most of the koftgari in place but there were some losses.

For a more heavily corroded piece, it might be a completely diferent story and I would like to know the answer myself. :shrug:


Your method is perfectly safe when the underlying crosshatched iron surface is uncorroded and there is a direct bond. Where you tend to get losses is when rust goes under the overlay metal. But the decoration is eventually doomed in such case because as the corrosion advances it will flake anyway. For the heavier corrosion you mention, I carefully use dental picks of various shapes, plus small horsehair brushes, to remove the rust BETWEEN the elements of the design (i.e. where the iron was exposed to begin with), working around the precious metal. Of course when the rust has spread under the overlaid design, the adhesion is poor and there is the real risk of loss. You just avoid hitting the deco, and hope for the best.

Note that gold koftgari tends to be more stable than silver. This is because gold does not oxidize or tarnish. Silver will, and moisture seeping underneath from adjoining rusting of the iron will accelerate the tarnishing and hasten the deterioration of the bond.

CharlesS 26th August 2017 11:46 AM

Ammonia is good for removing oxidation without damaging what is underneath.

Kubur 27th August 2017 08:43 AM

Thank you Guys
Well I'm not sure of what to do...
I might use the Picreator's Metal Decorroder, but I'm still afraid for the gold under...
Best,

kai 27th August 2017 10:20 AM

Hello Kubur,

Quote:
Well I'm not sure of what to do...
I might use the Picreator's Metal Decorroder, but I'm still afraid for the gold under...

Well, the gold won't be hurt... ;)
If the iron/steel is badly corroded, chances are high that the gold will get loose though. :(

If the rust really has grown over the koftgari a lot, most likely it will also have crept under it extensively and already detached much of it. Thus, considering that badly pitted blades are also tough to clean and achieve a decent visual appearance afterwards, too, one might prefer to stabilize the rust first (and try to preserve the piece as relic by controlling the storage environment). Extensive tannic acid treatment?

Has anybody tried to reattach gold remnants to a thoroughly cleaned/polished blade? Probably a hell of a job for thin koftgari, I guess! Still, it might be worth to try to document any remaining koftgari/motifs in detail and then to decide whether to go for stabilization of the status quo (and accepting possible further damage to the blade or attached parts due to storage conditions) or long-term preservation/restoration or even redoing the koftgari in traditional style.

Kubur, I believe it would be good to post some pics of the very piece you contemplate to restore for getting more targeted responses! ;)

Regards,
Kai

Martin Lubojacky 27th August 2017 11:26 AM

Hello Kubur,
My opinion is that this is task for the experienced restorer/conservator who has been working in some (army) museum for a longer time. already. It would be a pity to learn on some nice, old and valuable piece. If you donīt succeed, than you might have one piece as an "exclamation mark" (how not to do it next time) in your collection. I think it is worth to establish good relationship with such an expert and instead of buying another piece to invest in his work on your current piece. But, based on my own experience, I would only believe proofed expert (i. e working for the good museum longer time /two-three in the town/)).

In the case of a heavily corodated item, the silver and gold decoration, probably, is "undermined" with corrosion. If you do not stabilise this corrosion, the silver or gold coud fall off either immediately (when you clean it chemically without conversation/protecting/deactivating of undermined areas), or it could fall off after a years (if you just clean it mechanically, which may not touch you, but your successors).

Nevertheless I also tried to clean such items myself. I degreased the coftgari inscriptions with aceton or alcohol and covered it with a transparent lacquer, then (the lacqure should be removable with solvents). Than I tried to remove the rust mechanically with a special steel brushes used by goldsmith, around the inscriptions. If this did not help I used Chelaton III (trade mark used in the Czech Rep.) to remove the rust chemically - this is the most dangerous phase and I did it only when the inscriotion was covered by lacquer (which, probably, and I do not know if it was good or bad, soaked to the microscopic capilaries around and below . The result was acceptable (for me). But, still, I have doubts - I think that the corrosion below had also had to be pasivated chemically (e.g. by tanin), which I did I think only once. This definitely is not any "manual" or recommendation, jus a description how I did it. But, IMHO, you will never reach such result as a skilled museum worker, who has been restoring both for the deposit and the exhibitions. So it also depends how valuable is the piece, how you evaluate it.
Best,
Martin

Roland_M 1st September 2017 08:35 AM

Hi Kubur,

my favorite method is very simple. Just applying a thick layer of Ballistol-oil onto the rusted surface and wait. Once a week replace the old oil with new one. After a few weeks or months the rust slowly disapperars by itself.
This is the mildest method I know.
I would not recommend to use transparent lacquer, because it can rust under the lacquer.

Roland

Helleri 2nd September 2017 12:05 PM

I think you mean gold-tone. Gold is 99.8% chemically inert. True gold does not tarnish or rust under normal circumstances (it pretty much takes a laboratory). A gold coin in burnt and salted earth under a pile of corpses in a mass grave of an ancient raided village would look like newly minted pulled out of the ground 2000 years later. Gold also tends to be rather slick. SO any grime collected in deep crevices is not likely to be bound to it's surface through something like galvanic corrosion which effect lesser noble metals. It's merely cradling it and it should wipe clean with dry soft bristled brushing.

As for true silver. Wood ash and warm water. 1:1 ratio mixed into a slurry and a soft bristle brush. Flushing away the slurry afterward can be a bit annoying and a careful process depending on the nature of a piece. If that is a concern let it first dry fully (and naturally with no applied heat) and then dry brush it away. Nothing will reveal it's prime luster better.

But really I wouldn't personally want to do much more to silver then to dry buff it. As it is at it's most beautiful with a nice patina. A characteristic that tends to raise value in all respects.

Kubur 9th September 2017 11:26 AM

4 Attachment(s)
Hi Guys

Thank you all for your help
Here is the maximum that I can do.
I didn't want to go too far as there are bits of gold everywhere...

Kubur


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