Crystal Effect IHC's

Hobo.. I forget. What was I going to say,, Oh yeah I forget.

 

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I encountered this crystalline pattern on a few IH 1c that were housed in old 2x2s. I am uncertain of the brand name of the holders but, they were made in the 50's-60's and had green font w/ a space for the the year and denomination.

In my case this pattern was a result of toning from the "cellophane" holder. I did a bit of research and found that the cellophane from this period was susceptible to and often suffered from a fungal degradation caused by it's storage environment.

The pattern was removed by a simple dip which confirmed that the pattern was a result of "toning" and not improper mixing of alloys.

 

Bumped the thread for those who are interested. I took my 1898 IHC to a well known expert in the field a few days ago. He said the pattern is uncommon, and that my example is rather extreme. It occurs due to excessive annealing of the planchet. He did not suggest that might be due to something post-mint. I looked through several hundred IHC's while at the show, and did run across a few more, but the pattern is difficult to see without using a 10x or greater magnifier.

 

Just got home from Long Beach, Acanthite, it was great meeting you at the show, I'll post more on the LB thread...

Actually, David Lange is the Lincoln Expert, who wrote the book on them. Dr Sol Taylor as well, but these days, it's Lange. I saw him at the LB show as well.

 

That was great to see you guys as well, good to know your trip back to AZ went safely.

I was referring to Richard Snow, I figured he was the about the best I could ask at the show. I didn't see David Lange, actually I don't know what he looks like.

 

I would say it is crystallization from the annealing of the planchets. Actually the woodgrain and the crystal patterns seen here have similar causes. The woodgrain is caused by the slow cooling of the ingots which allows the crystals to form (and form larger), They are then stretched out into streaks in the rolling of the strip. The crystals seen on these coins is from the annealing the planchets receive before striking.

The reason for the difference in the toning is because as the metal cools and the crystals grow the alloy tries to separate so some of the lighter crystals have a higher zinc content than the darker ones do. The two slightly different alloys do not tone at quite the same rate and it causes the different colors. Dipping strips the toning off of both types of crystal and we can no longer see the difference. (When they wee new the woodgrain planchets appeared homogeneous as well. The woodgrain is not that apparent until the lower zinc content tone. The higher zinc areas do not tone as readily and so retain their lighter color.)