Re: How to remove yellowing from monitor?

["Hilary M. Turner" <hilarymichael@ozemail.com.au>]

Mark Cummings wrote:

> Hilary,
>
> I like your Vaseline idea very much, it sounds like it will work well.
> And I'm glad you pointed out the short falls of using bleach, I had the same
> thought myself. I know if it's left in a plastic spray bottle it will
> greatly reduce the life of the bottle and it's rubber parts. I wonder if the
> person who suggested this had any experience or was just taking a wild guess
> at someone else's expence.
> I have some severe oxidisation and stains on a non-Apple monitor (a clone
> actually) and was wondering what you think of the idea of using a sand
> blaster to strip it back while possibly maintaining a matt non-reflective
> surface, prior to hitting it with Vaseline.

    If you have a sandblaster of a rather small variety and use a low pressure
with a very fine grit sand and work very fast with great care it should work.

> I don't really like the idea of
> using sand paper (cross hatching or otherwise), because I doubt I could ever
> do it in such a way as to make an even pattern over the whole surface.

    Try a hot iron over say 40 grit sandpaper. this requires a lot of
experimentation so you need some plastic of the same type or work on the inside
surface and don't forget to support the other side well or you probably will
before the plastic.

>
> Another approach that I was seriously considering was repainting it in
> Acrylic paints,

    As far as paints go you must find one that has a compatible solvent or you
risk the same process as with bleach. Again experiment on a piece of plastic of
a similar type and leave it for a longer time period then you would if you were
painting it. If the plastic becomes very soft after about twice the normal
trying time then the solvent in the paint is to harsh. To do this drop a large
size drop with and eyedropper or straw on a small area to achieve the extended
time.

    REMEMBER:  Plastics are made from crude oil. Any chemical used in its
manufacture will either parish or melt the plastic.

> colour matched to the original. Although I havn't done this
> for any plastic cases, I have already restored two metal cases to their
> original colour and finish. One was a Generic CDROM external case that was
> badly scratched. And the other was the metal casing for an AMR 3.5" floppy
> drive which was also scratched. To get the colour match I took the original
> case to the local paint shop who used a colour matching device/computer. The
> inside of the case was still like new, so that's where the colour was
> derived from. Their computer tells them how much of what colours to add to
> how ever much paint you need. In my case they were happy to just make up a
> small 250ml (1cup) can, and it cost less than $10AU ($5US) for the paint.
>
> Mark
>

    Here's a little tip on matching joining parts. If one side is worded ,using
a hair dryer to worm the plastic and a couple of smooth pieces of board clamped
over the warp can restore the flatness. To ensure that the plastic does not
shrink the piece of board on the inside must be fitted so that as the plastic
cools it will not shrink along the length but rather in it thickness. So from
the start the length of board used to maintain the length is in place before you
start heating the plastic.

Hilary