I wasn't aware that steel was widely used. I ran into a few War era disks that originally thought were lacquer. A few of them had one crushed edge from rough handling in a steel cabinet and we determined they had a fiberboard base. Glass was more commonly used, especially from '42-'46. Glass was usually carefully marked as such because of the breakability. If not marked, glass is heavier and has almost no "flex" to it. Another giveaway is that if a glass disc is gently tapped on the edge, it gives slight ringing sound.
Aluminum discs usually show a metallic cross section where the hub was punched for the spindle. I've heard rumors that some glass discs were bonded to an aluminum hub, though.
Hope this helps.
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>>> John Dawson <[log in to unmask]> 4/23/2012 3:36 PM >>>
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.
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