Yellowed plastic case


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.



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).


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


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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