Corrosion pains

Joe R. rigdonj at cfl.rr.com
Mon Apr 4 15:17:11 CDT 2005


At 02:59 PM 4/4/05 -0500, you wrote:
>At 12:42 PM 4/4/2005, vrs wrote:
>>> I have been seeing the same thing with my C= GPIB cables (as well as
>>> certain tool handles from the same era).  AFAIK, it's inevitable with
>>> that sort of plastic.
>>
>>My RK05F has a white powdery junk all over the inside, and all the plastic
>>bits have hardened (some have shattered).  Is this the same problem?  I
>>figured something had caused all the plasticizer to boil out or something.
>
>Could be.  I thought it was either a mold from old finger-residue
>or the plastic decaying.  Any experts on plastic decay out there?
>Is it an out-gassing of plasticizer or infiltration of ozone, or both?

  None of the above. It's a fungus! It used to be common on just about
anything made of plastic* but must most companies include a fungicide in
their formulas to reduce/eliminate it. The plastizer also oozes out of the
plastic over time and the item becomes brittle. I don't know of anything to
prevent that except perhaps to refrigerate it to reduce the rate of the
chemical decomposition. The fungus is feeding off the plasticizer or the
plastic itself, I'm not sure which. STP and ArmorAll sell products in the
automotive stores that is supposed to reduce the rate of breakdown of
plastics and rubber in automobiles. You might try some of those. But I
think once the damage is done then there's nothing you can do about it.

   *Fungus on plastic was a huge problem in WW II in the pacific. The US
military finally started adding a powerfull fungicide to their equipment to
reduce it. That fungicide is that strong smell that you sometimes smell
when you first open military items that have been sealed up for a long
time. You still find a lot of military items marked "MRT". That stands for
"Mildew Resistance Treatment".

   Joe




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