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 Post subject: Re: Straigtening warped 78s
PostPosted: Sun Apr 15, 2018 4:46 pm 
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Victor III
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Does anyone know if there is a safe way to flatten laminated disks?

S-B-H


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 Post subject: Re: Straigtening warped 78s
PostPosted: Sun Apr 15, 2018 5:54 pm 
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Victor Monarch Special
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Who is John Galt?
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If a laminated record such as Columbia were put between the glass plates, put into the oven at room temperature, then brought up to 175 degrees, I don't understand why it would be any more at risk than a solid disc.

Please educate me, as I wouldn't have hesitated to do this with a laminated disc.

George P.


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 Post subject: Re: Straigtening warped 78s
PostPosted: Mon Apr 16, 2018 2:56 am 
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Victor III
Joined: Sun Mar 15, 2009 6:18 am
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phonogfp wrote:
If a laminated record such as Columbia were put between the glass plates, put into the oven at room temperature, then brought up to 175 degrees, I don't understand why it would be any more at risk than a solid disc.

Please educate me, as I wouldn't have hesitated to do this with a laminated disc.

George P.

The only fragility I see in laminated records is the difference in thermal expansion between the layers (paper and shellac). This creates tension between the layers and may create wrinkles and superficial cracks. The difference in moisture absorption between these layers also creates such stresses, but some experimentation would be required to figure out which of them is the most important environmental factor.


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 Post subject: Re: Straigtening warped 78s
PostPosted: Mon Apr 16, 2018 8:40 am 
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Victor Monarch Special
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Who is John Galt?
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Location: New York's Finger Lakes
CarlosV wrote:
The only fragility I see in laminated records is the difference in thermal expansion between the layers (paper and shellac). This creates tension between the layers and may create wrinkles and superficial cracks. The difference in moisture absorption between these layers also creates such stresses, but some experimentation would be required to figure out which of them is the most important environmental factor.


Agreed, but bringing the temperature up gradually (starting with a cool oven) should minimize any expansion differential, shouldn't it?

I'll need to dig out a junk Columbia and try this.

George P.


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