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Author Topic: Renaissance Metal De-Corroder?  (Read 5060 times)

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Offline Jeff K

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Renaissance Metal De-Corroder?
« on: February 27, 2016, 01:15:55 pm »
Anyone ever try Renaissance Metal De-Corroder? It's supposedly made by the same company that makes Renwax it's marketed as a metal safe corrosion remover, I assume it would also eat patina, but I have a couple of coins that I have given up on.  Both have soaked for months in distilled water and Gringotts to little or no effect, scalpels and picks bounce off of the encrustation and even an over night soak in MSR failed to remove all of it (though it did do wonders).  Finally, in desperation, I let them soak over night in lemon juice, the one shows no difference at all, it is still covered in some sort of powdery looking blue corrosion and the other has now gone from a decent looking encrusted coin to a completely stripped, badly pitted illegible shiny encrusted coin; the lemon juice, I'm afraid may have completely trashed it, yet the dark green scalylookong corrosion that I can't seem to remove remains.  At this point I want to kill this stuff even if it takes a damned jack hammer, just on principle, then maybe try to restore what's left to something resembling presentable.

So I have two questions, the first is will Renaissance Metal De-Corroder work?  The second is will Jax help hide the stripped pitted illegible mess the lemon juice left and maybe at least partially restore some of the detail?

One more question, any idea what this green crap is that seems to be immune to everything?

Offline daverino

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Re: Renaissance Metal De-Corroder?
« Reply #1 on: February 27, 2016, 09:51:28 pm »
I looked at the adverts for this stuff which is described as an "amine complex of oxo-hydroxycaroxylic acid", pH 4.0. My guess is that it is a mixture of ethylene diamine (en) and citric acid. The latter is just what you find in lemon juice, which is a citrus fruit and the former is a mild organic form of ammonia. It is described as working on copper based metals like bronze as well as on iron rust. This is very reasonable since citric acid dissolves rust by complexing with iron oxide and en is good for dissolving copper oxides like verdigris. I think that the difficulty here is that what works for fresh corrosion on modern coins and other metals may not work so well with ancients. The encrustations on ancient bronzes have been mineralized and are not so easily dissolved. Also, as your experience with lemon juice suggests, the acidity will likely attack the patina on bronze coins as fast as it attacks surface deposits that you are trying to remove. The stuff may be worth a try but I would not expect any miracles.

regards, Dave

Offline Matthew C5

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Re: Renaissance Metal De-Corroder?
« Reply #2 on: February 28, 2016, 12:53:45 pm »
Hi Jeff, the green junk is either very hard malachite or hydroromarchite.  I'll attach a good link for you below.  This stuff will be only removed by a very sharp scalpel-type blade to the point you desire.  You might reach shinny metal underneath, especially if you don't know what to expect for the coin.  If you think  it's worth the risk, or want to experiment, give it a try and try not to cut yourself;)  It's loads of work though.

Matt

http://www.mindat.org/min-1985.html

Offline Mayadigger

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Re: Renaissance Metal De-Corroder?
« Reply #3 on: March 11, 2016, 06:26:47 pm »
Ave!

I have a vast experience with the same.

Never, ever, place any coin, no matter how corroded, in Renaissance Metal De-Corroder, trust me, I know. It will not only strip it down to the base metal, but entirely remove any and all details and legends.

But on the other hand, I do recommend it for cleaning ancient artifacts. Consider a Roman copper alloy buckle whose iron pin has rusted/degraded until it has, over time in the ground, become firmly affixed to the copper buckle.

Application of RMDC to the rusty parts via a cotton swab - Apply and allow to set in for at least 12-24 hours. Scrape and the remove the now emulsified rust with dull-bladed scalpel. Repeat until all of the rust has been removed. Once done, soak in DW for 24-48 hours...and Bob's your uncle!

Best to all,

Kevin
"Goodbye, Livia: never forget our marriage!"

Offline SC

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Re: Renaissance Metal De-Corroder?
« Reply #4 on: March 13, 2016, 02:06:15 pm »
After taking photos to note for posterity that the item once had certain iron parts…..

Shawn
SC
(Shawn Caza, Ottawa)

Michael C3

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Re: Renaissance Metal De-Corroder?
« Reply #5 on: September 29, 2019, 02:08:41 am »
Ave!

I have a vast experience with the same.

Never, ever, place any coin, no matter how corroded, in Renaissance Metal De-Corroder, trust me, I know. It will not only strip it down to the base metal, but entirely remove any and all details and legends... ...
Best to all,

Kevin

Thanks all for the valuable info and advice :-)

Has anyone experience with applying Renaissance Metal De-Corroder _only to the corroded spots_ on ancient coins—that is by first masking off patinated areas of the coin with impermeable wax?

Also, what about pure EDTA?—a presumably key component of this de-corroder. I work in a haematology lab where EDTA is routinely used to anticoagulate patient blood samples for blood-count testing without damaging the delicate human blood samples. Can anyone offer any further technical advice re EDTA and coins?

Thanks,
Mike

Offline TenthGen

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Re: Renaissance Metal De-Corroder?
« Reply #6 on: October 02, 2019, 07:28:47 pm »
EDTA also chelates copper, so I would anticipate that it would also corrode any copper or copper alloy coins. That said, I've never seen or heard of it being used.

Offline B-Chicago

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Re: Renaissance Metal De-Corroder?
« Reply #7 on: October 10, 2019, 01:30:49 pm »
NEVER use lemon juice on copper or bronze

worst thing ever

it's kind of hard to recover from that

have not heard of the other but have the wax but haven't used / tried it yet

I have also never tried MSR - looks and sounds like a bad idea

first thing you should stock up on is patience

sometimes it takes years for the surface crud to start breaking down

try soaking them is hot soapy water for an hour two when you pull them out of the water for rinses / scrubs

sometimes that helps

don't be afraid to boil in water with a healthy dose of baking soda - try with lower grade frustrating coins to get a feel for it

sometimes that puts a dent in the verdigris - it does break down some hard as rock dirt

and if you haven't seen me mention this before make sure you clean the containers you soak them in every swap out of coins and water

they get real grimy

only change the water when its clear its done something - visible goo or an oily surface muck are good indicators







 

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