The Museum of HP Calculators

HP Forum Archive 15

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Yellowed plastic case
Message #1 Posted by Arnaud Amiel on 12 July 2005, 5:19 a.m.

Just got my hands on a nice (Non HP) adding machine however its plastic case is all yellowed. Does anyone know to restaure it to its original colour. Is it even possible. How can I avoid my other calculators turning dirty yellow. Thanks for your suggestions.

Arnaud

      
Re: Yellowed plastic case
Message #2 Posted by Frank Boehm on 12 July 2005, 8:21 a.m.,
in response to message #1 by Arnaud Amiel

Assuming it is not dirt, you probably can't do anything about it. It's a non-reversible chemical reaction (UV rays modifying plastics). It might be possible to use H2O2 (try it on a hidden surface) to bright it up, I doubt it though.

The only way to prevent yellowing is to hide the item in a dark, dry, cold place. If you want to create a showroom, there is special glas (UV blocking) available - you do need special lighting as well (UV free).

            
Re: Yellowed plastic case
Message #3 Posted by Chan Tran on 12 July 2005, 4:27 p.m.,
in response to message #2 by Frank Boehm

If the calc isn't too valuable I would suggest to try chorine beach.

                  
Re: Yellowed plastic case
Message #4 Posted by Gary on 18 July 2005, 5:30 p.m.,
in response to message #3 by Chan Tran

Some restoration may be possible by using using jewelers rouge to polish away a thin layer of plastic. If the yellowing is deep, this won't work. An alternative is vinyl dye or the new plastic bonding spray paint( assuming you can find a suitable color.).


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