Classical Numismatics Discussion
  Welcome Guest. Please login or register. STORE WIDE SALE!!! 10% OFF EVERYTHING!!! WE ARE OPEN AND SHIPPING!!! We Are Working From Home, Social Distancing, Wearing Masks, And Sanitizing To Pack Orders!!! Please Call Us If You Have Questions 252-646-1958 Welcome Guest. Please login or register. STORE WIDE SALE!!! 10% OFF EVERYTHING!!! WE ARE OPEN AND SHIPPING!!! We Are Working From Home, Social Distancing, Wearing Masks, And Sanitizing To Pack Orders!!! Please Call Us If You Have Questions 252-646-1958


FORVM`s Classical Numismatics Discussion Board  |  Numismatic and History Discussions  |  Coin Photography, Conservation and Storage  |  Topic: Fighting Bronze Disease 0 Members and 1 Guest are viewing this topic. « previous next »
Pages: [1] Go Down Print
Author Topic: Fighting Bronze Disease  (Read 90 times)
otlichnik
Tribunus Plebis 2016
Procurator Monetae
Caesar
*****
Offline Offline

Posts: 4295



« on: March 19, 2020, 03:33:48 pm »

I recently read a short paper on bronze disease: Corrosion Risk Assessment Approach in Archaeological Bronze Collections: From Burial to Long-term Preservation Environments, by Iranian professor Omid Oudbashi.

https://www.academia.edu/28911095/Corrosion_Risk_Assessment_Approach_in_Archaeological_Bronze_Collections_From_Burial_to_Long-term_Preservation_Environments

The findings are very interesting and confirm much of what we already believe.

First, the chloride content of the soil is critical.  Bronze objects that come from a high chloride content soil are in effect already doomed.  A chloride content of less than 10mg/kg of soil is ideal as items are safe even in a wet environment.  A content of 10-100 mg/kg is ok in dry and semi-dry environments but is bad in more humid environments.  Higher chloride content is bad.  Above 1000mg/kg is very bad.

Second, the humidity of the modern storage environment is critical.  At less than 40% humidity even high risk objects should be safe from deterioration.  The 40-55% humidity zone is bad as that allows for the bronze disease reaction to begin or continue.  Over 55% humidity is really bad....

Invest in those de-humidifiers.

SC

Logged

SC
(Shawn Caza, Ottawa)
Dominic T
Caesar
****
Offline Offline

Posts: 408



« Reply #1 on: March 19, 2020, 03:51:40 pm »

I know Potassium Chloride is use as agricultural fertilizers. Probably the modern soil where coins are sometimes found are saturated with this chemical, explaining the problems found on some bronze pieces.
DT
Logged
otlichnik
Tribunus Plebis 2016
Procurator Monetae
Caesar
*****
Offline Offline

Posts: 4295



« Reply #2 on: March 20, 2020, 01:33:27 pm »

Exactly.  It seems that there are areas where the soils simply has a high chloride content - especially in certain desert or arid regions - but then there are areas where the chloride content has been anthropomorphically increased, such as due to fertilizer use.  Also, I recall reading somewhere that some forms of vegetation, such as evergreen needles, can cause the chloride levels to spike.

I think that the fertilizer explains the crappy conditions of some UK, French and Austrian uncleaned coins I have had in the past....

SC
Logged

SC
(Shawn Caza, Ottawa)
Dominic T
Caesar
****
Offline Offline

Posts: 408



« Reply #3 on: March 20, 2020, 02:20:01 pm »

In a publication brought to the publics attention by news release from the University of Illinois several years ago, the Department of Natural Resource and Environmental Sciences at the University of Illinois challenged a number of basic tenets of soil fertility, especially practices related to use of potassium (K) fertilizer. Citing hundreds of references and thousands of reported studies, they asserted that: K fertilizer is generally unnecessary in soils like most of those in Illinois; the soil test is not a reliable way to know how much K the soil will supply to a crop; K used as fertilizer can cause crops to have lower nutritional value; using K fertilizer can damage soil structure; and potassium CHLORIDE (KCl), which is the most commonly-used (and lowest-cost) K fertilizer material, is harmful to crops. They didn't know it's also harmful for coins!
DT
Logged
Pages: [1] Go Up Print 
FORVM`s Classical Numismatics Discussion Board  |  Numismatic and History Discussions  |  Coin Photography, Conservation and Storage  |  Topic: Fighting Bronze Disease « 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 0.508 seconds with 28 queries.
Forum Ancient Coins
PO BOX 1316
MOREHEAD CITY NC 28557


252-497-2724
customerservice@forumancientcoins.com
Facebook   Instagram   Pintrest   Twitter

zoom.asp