A funny thing happened to my 29C...


I have an HP-29C that has been in storage for a few years. It seems to have absorbed some of the "black" from the inside of it's case into the tan/yellow outer shell. Warm water, kitchen cleaner, and a toothbrush didn't budge it. Looks like it's stained for good. It's faint, but bothersome as this was my mint-in-the-box 29C. The inside of the case was padded black fabric, whereas most of my other woodstocks have a tan fur lining. So, if you have a woodstock with a case with a black interior - beware.


Try white gas (Coleman camping fuel). Removes most sticky stuff. Will not affect plastic cases. Also, toss that zip case into the washig machine. Your shedding goo problems will go down the drain,


I know I have read somewhere, that the white gas will surface damage the plastic. However, I assume you have used it with good results.


I was mistaken. I had read on a Curta site not to use the Coleman fuel on the outside of a Curta.


Well, it's not really gooey, and the case isn't shedding. I used to test E series cases by tapping the unzipped case over a sheet of white paper. Almost all would leave a black dust residue. I'm not getting that from this case. Maybe it's just getting ready to go. It has been stored in a low pressure environment for the past few years - perhaps there was some outgassing. Maybe I'll switch to dry nitrogen... Dammned oxygen. Can't live with it, can't live without it.


Actually the residue is gooey and the case is shedding... it's a dry goo. You just can't feel it. I have seen the problem numerous times.

Coleman fuel does not affect most plastics. It is the best thing for removing sticker residue, etc. Also works fairly well for markers and ink. Keep it off the keyboard. My standard way of fixing badly scratched display windows is red jewelers rouge dampened with Coleman fuel. As with all commercial products, Coleman may get a wild hair up their alien probe hole and change their formula without notice. Test in an inconspicuous place if you are worried.


Ahhh... interesting. I suppose very tiny particles of goo would behave differently than a larger blob of goo. Like the way a very fine powder behaves as a liquid - a lot depends on the particle size. I'll try the Coleman fuel. I also noticed the rough texture of the case is much more evident than a typical woodstock - presumably from close to zero handling since manufacture. I have a 25C that's almost slick compared to it. I suppose that rough surface would provide better nooks and crannies for the goo particles to take up residence and avoid being washed away without using a solvent (like Coleman fuel) to actually dissolve them.



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