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XRF ANALYSES $5 PER SCAN!Jonathan Brecher has been reaping the research benefits of a very affordable service offered by author Winston Zack. Others may want to give it a try. -Editor
XRF is a non-destructive method that can measure metallic composition without risk even for valuable objects. It's not a new technology, mentioned in E-Sylum as early as 2012. The main drawback to XRF has been the price. Commercial XRF machines have been available for more than 20 years, but the price has never fallen to the "hobbyist" level. A new machine typically costs $20,000 or more. Some people may know someone with an XRF machine who is willing to run some tests for them as a favor. I don't have that option. Commercial services may charge $150 or more per scan. As a collector of tokens and medals, I have many pieces in my collection where I wondered about their composition. I would have continued wondering, rather than pay those prices. When I saw that Winston was offering XRF analyses through his website https://www.badmetalcoin.com, I jumped at that. I can satisfy a lot of curiosity at his rate $5 per scan! I ended up testing over 100 pieces, mainly So-Called Dollars. The results were fascinating, and I've written them up at https://www.so-calleddollars.com/XRF_results.html, with lots of pictures and discussion. The "yellow-colored" medals provide good examples of the sort of questions that can be answered by XRF. The So-Called Dollars book originally by Hibler and Kappen described HK-694 as bronze, HK-481 as gilt bronze, and HK-415 as gilt brass. XRF shows that all three varieties are actually brass (85% copper, 15% zinc) with no hint of any sort of gilding. The book lists HK-69, HK-245, and HK-304 all as gilt bronze. XRF confirms that all three of those varieties indeed are gold plated — but only HK-245 is gilt bronze. HK-69 is actually gilt copper, while HK-304 is gilt brass. 
HK-694 (brass) and HK-481 (brass) 
HK-415 (brass) and HK-69 (gilt copper) 
HK-245 (gilt bronze) and HK-304 (gilt brass) I know a lot more now that I've seen the XRF results. I also see how much more could be learned. It would be great if others could test their own pieces, and share the results! Many thanks to Winston for offering this service and Jonathan for helping get the word out. What discoveries are waiting to be made? -Editor Jonathan adds: "A recent thread on the PCGS Message Boards discusses some limitations of XRF. Because XRF analyzes the surface of an object to a microscopic depth, it can give confusing results for plated pieces. The XRF results will usually include both the plating and the base material, with the plating over-represented in terms of percentages. For the pieces I tested, gold plating typically registered at 1-3%, while nickel, cadmium, or chrome plating registered at 5-25% and silver plating in some cases registered at 30% or more. The results are still useful for plated pieces, just with a little more interpretation. "Unsurprisingly, XRF also gives poor results when the surface is obscured. It's not a good idea to analyze pieces that are already slabbed. That thread points to an interesting analysis from the British Numismatic Society, showing clearly how the thickness of a slab interferes with the scans. Raw coins are certainly the best way to get accurate XRF results."
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To read the earlier E-Sylum article, see:
Wayne Homren, Editor The Numismatic Bibliomania Society is a non-profit organization promoting numismatic literature. See our web site at coinbooks.org. To submit items for publication in The E-Sylum, write to the Editor at this address: whomren@gmail.com To subscribe go to: Subscribe All Rights Reserved. NBS Home Page Contact the NBS webmaster 
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