"screen mold"

[Dwight K. Elvey]

>From: "Vintage Computer Festival" <vcf at siconic.com>
>
>On Tue, 4 Oct 2005, Andreas Holz wrote:
>
>> I'm experiencing some monitors in the last time, mostly, but not only
>> from HP, with the effect of some kind of small bubbles or shell-like
>> failures in the flront part of the crt-tube. Somewhere I read the
>> description of "screen mold".
>
>Nowadays the consensus is leaning towards a delamination process.
>
>> Does someone knows this effect, has an explanation of it's source (is it
>> really temperature related?) or how to avoid this problem. Some of these
>> monitors (esp. of a HP9845) are looking so badly, that I don't dare to
>> power on.
>
>Most likely it is the protective cover over the CRT which is delaminating
>from the CRT face.  I don't currently know of a way to prevent this.  It
>seems to happen randomly.
>

Hi
 I think it is from evaporation of plasticizers in the layer.
As they evaporate over time, the material shrinks. This causes
a void. The void provides another path for the plasticizer to
evaporate and a local stress point. This forms the stem like
channel feature. As time goes on, plasticizer evaporates from
the edges of the channels. This causes new stems to radiate
outward. This makes the typical fern leaf look.
 I would guess the biggest difference between different
manufactures is either a different material or different
sealing of the edges.
 The fogging of the material is most likely moisture from
the air.
Dwight