My First Classic

[Thomas Okken]

(08-21-2018 02:18 PM)sasa Wrote:  

(08-21-2018 08:32 AM)jebem Wrote:  - Cleaning the keyboard and face plate with agressive or even alcohol based products. This is the way to have the labels removed or just faded away if you are lucky.

Interesting. Do you know what exact paint (chemistry) and process was used to make labels on HP calculators in early 70s?

Many images shows they fade out after long usage, caused probably by oil from skin or a bit aggressive rubbing, especially around On/Off switch.

The labels printed on the face plate don't fade, as far as I'm aware, but they rub off very easily, and you don't need solvents for that to happen, either. I noticed this once while trying to clean the keyboard on my HP-25, when it was still new; after a bit of rubbing to remove a spot of grease between two keys, the INT label was half gone. Oops! Luckily my fingers are thin enough that I never hit the face plate by accident, and ever since I only clean the face plate by gently wiping it with a soft, dry cloth. The HP-67 and another HP-25 that I got more recently have good face plate labels, could be that they looked a bit crisper when those machines were new, but they look fine to me now as well.