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Ignatz · 11-21-2019, 10:05 AM

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HP25 HP45 by Tim Danaher, on Flickr[/img]

Will have some questions about these two lovelies later...

Maximilian Hohmann · 11-21-2019, 12:06 PM

Hello Tim,

A nice pair, congratulations for your find. If you want to get rid of the superficial scratches in the displays I can recommend a product called "polyWatch". It is a very mild polishing paste for watch glasses, which are often made from plastic, but works with these calculator displays equally well. You can buy it cheaply on the internet. It will not remove deep scratches but I can't see any in the pictures.

And be careful when cleaning the keyboards. Don't use solvents, not even alcohol. 40 year old sickscreen paint is very fragile and you can easily end up with an entirely blank keyboard... apart from the main labels on the HP-25 because these keys are "dual shot injection moulded" and almost indestructible. Just use liquid soap (I use the stuff for washing dishes) and water.

Regards
Max

Ignatz · 11-21-2019, 08:38 PM

Excellent! Cheers, Max!!!

Ignatz · 11-21-2019, 08:54 PM

I took these into work today, and mentioned the injection-moulded key caps: a lot of my colleagues flat-out refused to believe that they could have made something that fine and so precisely moulded “back in the Stone Age”, as one of them put it ???

And, yes, I look at the screen-printed rubber keys on my HP35S and think about what might have been...