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Removing hard glue from HP-28S? - Printable Version

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Removing hard glue from HP-28S? - Holger Weihe - 01-03-2003

Hello,

I recently got a 28S. It is in good condition except some glue in the cover. It is very hard glue, not like from textile band. The glue is above the alpha-keypad and covers the onprinted documentation.

Do you know any good method of removing such glue without damaging the calculator? I tried to cut it away with a knive, but only some sand-like parts came off. How durable is the printed documentation in the cover? Can I continue scraping on it and try several chemicals or better not?

Are there any chemicals which soften the glue but not the calc?

A bit of the same glue is on the calculators backside. Because of the bumpy surface there, it will be impossible to mechanically remove the glue without removing some of the calculators plastic. What could I do here?

Thanks for any advise...

Holger


Re: Removing hard glue from HP-28S? - Vieira, Luiz C. (Brazil) - 01-03-2003

Hi;

I tested an "all-glue removal" once, from Loctite, the same co. that produces SuperBonder. I still have it, and it is composed by Propylene Carbonate. Maybe you can find it easier, because I bought it in a small supermarket. Also, all inscriptions are in Portuguese, so I do not have the original names in English, just the translations.

Unfortunately it not only dissolved the glue (SuperBonder) but also melted the plastic where it was. Anyway, if I understood it well, your HP28 has glue over the upper left-shell, the one with the ALPHA keyboard, where you read some information about the different object types that the HP28 can deal with, right? This printed portion of the shell is protected by a rugged, transparent coat (acetate?). MAYBE this material is not melted by the all-glue removal, you should try. The worst is that I am not sure about what material is this protective coat made of, so you could test it before using in the calculator itself.

If you have any success, let us know, please.

Best regards.


Re: Removing hard glue from HP-28S? - David Smith - 01-03-2003

I have found that Coleman camping fuel (white gas, cigarette lighter fluid) works very well ad removing most adhesives, paint residues, and sticky gunk from calculator cases. It does not seem to affect the case or labels. I can leave some "water marks" on the keyboard backgrounds.

Also strong (91%) isopropyl alcohol works well. Unfortunately it can cause some clouding of clear display windows (which can be cleaned off) and on a few labels it can remove the ink. Whatever solvent you try, first test it in a hidden area.


Re: Removing hard glue from HP-28S? - Holger Weihe - 01-04-2003

Thanks for your hints so far. Until now I tried everything I found at home but no success. (desinfection spray, terpentine, Isopropyl, lighter-gas, barbeque-grill-cleaner, rust-solver... I will buy some aceton next week.

By the way - the HP28 is very durable! The above chemicals did not damage it. (I wouldn't try that with a more valuable calc of course!)

Maybe I should burn it off? ;-)

Holger




Re: Removing hard glue from HP-28S? - David Smith - 01-04-2003

DON'T use acetone. It will definitely remove the label paint and damage the plastic.


Re: Removing hard glue from HP-28S? - Vieira, Luiz C. (Brazil) - 01-04-2003

I'd say the same about acetone! Do not use it. Definitely will damamge the painting (even the cover) or leave watermarks. (cloudy white spots)

But burning it out? Oh, boy! ;-D


Re: Removing hard glue from HP-28S? - Holger Weihe - 01-05-2003

Hello David and Luiz,

UH, thanks for your acetone-warning! I will let it in the shop. Maybe it is the best to leave the calculator as it is.

I have another HP-28S without glue, but with a broken battery compartment. Maybe I'll try to exchange some parts between the two.

Holger