Have just bought my first Curta, which works well and I'm very pleased with it.

However, the previous owner had left it for some time out of the case and in a dirty environment, with the result that the zero digits on the upper registers are soiled and hard to read. I'm looking for info about the best way to clean them.

My instinct is to disassemble until the digits are exposed, but that looks like a reasonably tricky operation. Is it possible to do a good clean through the little digit windows? I'm concerned about fibres and solvents escaping into the inside of the calculator.

What solvents are recommended (or warned against!) for cleaning Curta parts?

Hi Austin

Yes, the best way for cleaning is a total disassembly... but... that's not so easy.

The other way is to clean the digits from outside - you need
- patience
- alcohol (or a similar solvents - not critical because all parts are metal)
- toothpick
- q-tips
- soft rubber (like plasticine)
- patience

Then you start with a wet q-tip the battle against the dirt... never too wet so that nothing drops inside. Then drying and - repeat until the digit is blank. In case you can remove some harder dirt with the toothpick and the rubber.

That's it... happy cleaning

Thanks for that; I'll give it a go.

murff wrote:

- alcohol (or a similar solvent - not critical because all parts are metal)

I was thinking maybe the numerals are painted on, and so the solvent used would be important?

The dials are made of black anodized aluminum, engraved



So no worry...

murff wrote:

The dials are made of black anodized aluminum, engraved ... So no worry...

OK, thanks for that.

Yup, a wet toothpick is the way to go. And a lot of patience... good luck!