Hydrogen peroxide gave me wonderful results. But like you said, it's
expensive. So I don't buy hydrogen peroxide. I buy hair bleaching gel.
Buy it at "40 Volume" or (even better) "50 Volume" concentration. That
means it's 15% hydrogen peroxide, plus some other chemicals to make it a
gel that stays in place when you apply it. I was able to get a liter of
that stuff for about $15US, and since it's not made for use in a
laboratory or anything, it's not too hard to find, and it's cheap. Smear
that on the yellowed plastic, put the parts in a clear plastic bag to
prevent evaporation, and put it outside on a sunny day. The ultraviolet
light from the sun reacts with the peroxide and pulls the yellow out of
the plastic with no damage to the original color, texture, or integrity
of the part. A full day in the sun cleans up most parts.
Hope this helps!
--Justin
On 10/21/21 3:36 AM, Jamil Alioui wrote:
Hello to all of you,
I have a small practical question, which will be my first on this
list. I quickly looked in the archives but found nothing about this. I
hope to knock on the right door.
What is the best method to whiten the yellowed plastic of a Model 100
without damaging the screen or sanding (=smoothing) the relief or
erasing the inscriptions? I found several possibilities on the
internet. One of them is to rub the material with a baking soda paste.
But the one time I tried this, the matte plastic turned shiny. I
considered dipping the case and keyboard keys in household vinegar,
but wanted to make sure it wouldn't affect anything else. I also
imagined bathing the yellowed parts in hydrogen peroxide, but this
product is very expensive in Switzerland.
Thanks in advance; kind regards,
Jamil Alioui
(Lausanne, Switzerland)
