Plastic Restoration

TugboatEng · Dec 26, 2019

I have just aquirred one of the first tablet computers from the early 1990's. The plastic housing is softening to the point where it feels sticky and can imprint fingerprints. I have a hunch that, having been stored in a closed container with the NiCad battery, it has been exposed to potassium hydroxide fumes. I am guessing the housing is polycarbonate. Is there any way to reverse the softening?

3DDave · Dec 26, 2019

Since potassium hydoxide is basic then reversing the damage, if possible, would come in the form of an acid. I note that polycarbonate is resistant to acetic acid in moderate to high concentrations, but it may take as long to fix as it did to fail in the first place. Still, it might be good enough to solidify the surface. Try on a small area. See

https://www.calpaclab.com/polycarbonate-chemical-compatibility-chart/

I'd try plain white vinegar to start.

TugboatEng · Dec 26, 2019

It may also be ABS plastic. I had a bit of Ospho (phosphoric acid so I have applied some and am waiting for results if any.

Compositepro · Dec 26, 2019

You cannot reverse the chemical degradation of plastics.

TugboatEng · Dec 27, 2019

Yeah, I should probably part it out for someone who has a good case. It's an old EO 440 computer.

chicopee · Jan 7, 2020

Go on E-bay and see if there are any of those units on sale to replace the housing.

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