ENLARGING POLYMERS AND COUNTERFEIT DETECTION

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V17 2014 INDEX E-SYLUM ARCHIVE

The E-Sylum: Volume 17, Number 19, May 4, 2014, Article 9

Bob Van Arsdell submitted these thoughts on implications to the hobby of enlarging polymers, reported here by Dick Johnson last week. -Editor

The post about the "enlarging polymer" offers a solution to a counterfeit detection problem I've been working on.

I have a 1887 Victoria Crown which appears to be a good quality lost wax casting. It even has the sprue phonied up as a "rim ding". The only problem is the coin is full weight (within the remedy of the 1870 British Coinage Act), and the diameter of the coin looks OK (within a few 100s of a mm of what would be expected). However, if it's a lost wax casting, it should be 2-3% underweight and the diameter should be similarly undersized.

By using the enlarging resin, and soaking it only long enough to increase the mould 3%, the problem of differential shrinkage is solved.

I don't see how mentioning the name of the product could somehow "let the cat of the bag" in this day of instant access to everything. The company's website shows coins being made.

The sooner that authenticators know about this material, the better. Up to now most would assume that lost wax castings have to be underweight and undersized. That old crutch no longer holds, folks.

I agree with Bob that withholding the company's name is probably unnecessary, but I'll respect Dick Johnson's wish and not mention it here. I did locate the firm's web site and watched their product video. I captured the above image where the narrator is holding a Morgan dollar in one hand and a greatly enlarged copy in his other.

Bob's note solves one additional mystery for me - the material expands in water at a known rate, so to expand something by a given amount, you remove it from the water at a precise time. This still allows for some variability, but at a decreased level of inaccuracy. -Editor

To read the earlier E-Sylum article, see: HONEY, I SHRUNK THE MEDALS! (www.coinbooks.org/esylum_v17n18a12.html)

Wayne Homren, Editor