Maybe give a magnet a try!

Mark Shakarjian

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On Apr 23, 2012, at 12:36 PM, John Dawson wrote:

Hi everyone,

I was wondering if anyone had tips/resources about determining whether or not a the substrate of a laquer is steel or aluminum.  I have some WWII era discs and some are definitely heavier and sturdier than others.  I am wondering if these are steel. 

John Dawson
Indiana University
Media Preservation Initiative