Classical Numismatics Discussion
  Welcome Guest. Please login or register. Please look at the RECENT ADDITIONS and PRICE REDUCTIONS at the top and bottom of the page. All items are guaranteed authentic for eternity! Please call if you have questions 252-646-1958. Welcome Guest. Please login or register. Point your mouse to a coin in RECENT ADDITIONS or PRICE REDUCTIONS on this page to see the the price. All items are guaranteed authentic for eternity! Thanks for supporting Forum with your PURCHASES!


FORVM`s Classical Numismatics Discussion Board  |  Numismatic and History Discussions  |  Uncleaned Ancient Coin Discussion  |  Topic: Renaissance Metal De-Corroder? 0 Members and 1 Guest are viewing this topic. « previous next »
Pages: [1] Go Down Print
Author Topic: Renaissance Metal De-Corroder?  (Read 2077 times)
Jeff K
Praetorian
**
Offline Offline

Posts: 23


« on: February 27, 2016, 11:15:55 am »

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?
Logged
daverino
Caesar
****
Offline Offline

Posts: 545


WWW
« Reply #1 on: February 27, 2016, 07:51:28 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
Logged

Matthew C5
Consul
***
Offline Offline

Posts: 373


« Reply #2 on: February 28, 2016, 10:53:45 am »

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
Logged
Mayadigger
Caesar
****
Offline Offline

Posts: 1651


Romans, lock your wives way!


WWW
« Reply #3 on: March 11, 2016, 04:26:47 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
Logged

"Goodbye, Livia: never forget our marriage!"
otlichnik
Tribunus Plebis 2016
Procurator Monetae
Caesar
*****
Offline Offline

Posts: 4114



« Reply #4 on: March 13, 2016, 12:06:15 pm »

After taking photos to note for posterity that the item once had certain iron parts…..

Shawn
Logged

SC
(Shawn Caza, Ottawa)
Michael C3
Auxiliary

Offline Offline

Posts: 1


« Reply #5 on: September 29, 2019, 12:08:41 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
Logged
TenthGen
Consul
***
Offline Offline

Posts: 173


« Reply #6 on: October 02, 2019, 05:28:47 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.
Logged
B-Chicago
Praetorian
**
Offline Offline

Posts: 55


« Reply #7 on: October 10, 2019, 11:30:49 am »

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






Logged
Pages: [1] Go Up Print 
FORVM`s Classical Numismatics Discussion Board  |  Numismatic and History Discussions  |  Uncleaned Ancient Coin Discussion  |  Topic: Renaissance Metal De-Corroder? « previous next »
Jump to:  

Recent Price Reductions in Forum's Shop


Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!
Page created in 1.395 seconds with 37 queries.