Reply to Thread

Message:: [QUOTE="Jimski, post: 2968211, member: 77373"]Looking at the coin below, one probably would think it is grossly environmentally disfigured.  But I don't think the bubbly surface is due to environment.  References below support the idea that coins with that bubbly effect, left the mint that way. Below, an example of the blistered, bubbly surface found on some of Wood’s Rosa Americana coins.  My poor, dear Rosa.  I bought this coin because I thought that the bubbly appearance was an example of Wood’s difficulty controlling his minting process. [ATTACH=full]727763[/ATTACH] [ATTACH=full]727764[/ATTACH] The following 2 references well explain the bubbly appearance of the posted coin.(Text in curly brackets {} are my additions to the author’s content, which is in italics.) 1)  From Walter Breen’s Complete Encyclopedia of US and Colonial Coins, 1988:The patent represented Wood as the inventor of a new alloy in which the {Rosa Americana} coins were to be struck. Woods coinage metal … is a form of brass under the euphemism “Bath metal” = 75% copper, 24.7% (zinc), and 0.3% (silver). …{Breen continues …}the blanks were heated before striking, presumably to soften them enough to minimize die breakage.  This explains why many uncirculated survivors are discolored, showing local porosity and bulges from trapped gas bubbles. 2)  And from the archives of the British Numismatic Society’s British Numismatic Journal (BNJ)  <a href="http://www.britnumsoc.org/publications/Digital%20BNJ/pdfs/1903_BNJ_1_14.pdf" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.britnumsoc.org/publications/Digital%20BNJ/pdfs/1903_BNJ_1_14.pdf" rel="nofollow">http://www.britnumsoc.org/publications/Digital BNJ/pdfs/1903_BNJ_1_14.pdf</a>THE COINAGE OF WILLIAM WOOD FOR THE AMERICAN COLONIES, 1722 - 1733.By PH1L1P NELSON, M.D., member of the Numismatic Society of LondonPublished by Brighton, W. C. Weight, 1903.The blanks for these coins were heated prior to being struck by the die, which was elevated to some height and then allowed to descend, and this no doubt accounts for the many specimens which appear blistered, as though they had been subjected to the action of fire. Notice that Breen says that many “uncirculated” (Rosa Americana) coins are discolored, and show bulges.  So the coins were minted with the bubbly defect. I think these bubbly coins are due to Wood’s failure to fully understand or control his unusual metal and minting process.  I presume that some factors of incorrect final temperature before striking, properties of the individual planchets, or impurities in the metal … sometimes led to, as Breen states, porosity (if gas escaped from the coin), or bulges (i.e. blisters/bubbles, if gas was trapped).  Wood’s bath metal was only used on the Rosa Americana coinage.  His later Hibernia coinage was struck in copper.  I don’t see the bubbly condition on Wood’s Hibernia which supports the idea that Wood’s bath metal and/or his minting process caused the bubbly appearance. This bubbly appearance is not uncommon among Rosa Americana coins. Here are some other examples of Rosas with similar appearances (not my coins). [ATTACH=full]727768[/ATTACH] [ATTACH=full]727771[/ATTACH][ATTACH=full]727773[/ATTACH] On this next coin, some of the bubbles are broken revealing the void created by the trapped gas. [ATTACH=full]727777[/ATTACH] And one photo of the porosity that Breen noted. There is extensive porosity from 8:00 to 12:00. [ATTACH=full]727778[/ATTACH][/QUOTE]

Create my FREE Account!

Log in or Sign up

Reply to Thread

Useful Searches