I am sorry to be coming back to this so late but I just returned from a
trip abroad and only found the postings on this topic yesterday.
Fist of all, I will let out some venom for the makers of cameras who put
this polyurethane foam in their products. This stuff is predestined to
turn to paste, damaging the camera in the process. Considering the price
of a quality camera and the fact that a good camera SHOULD last for many
decades, the manufacturers ought to be forced to repair the damage without
cost to the owner of the camera. This foam is like a time bomb in the
machine.
It makes no difference what I think, a lot of you have cameras with this
paste in them and need a fix. As has been suggested, felt is something to
think about, but there are a couple other materials offering a lot of hope.
One is soft leather, like chamois. Generally this will be a little thin
if used as a single layer and multiple layers will not be as soft as PU
foam; however, consider forming a tube with the seam of the tube glued
down, away from the side getting slapped by whatever is falling on the
tube. You might even put a bit of something in the tube (see below!).
Unfortunately leather also does not offer an infinite lifetime and in time
it will get brittle and fail, but the mess will be easier to cleam up than
what you have when the PU foam reaches the end of its life.
There is a better longterm outlook for silicone foam (Sounds somewhat like
"silly cone", and not to be confused with "silicon", which many persons do,
because silicon is a hard element which is brittle and quite useless for
this task.) Look for this foam at your DIY shop. I have bought it as a
seal for doors and windows. The most convenient form is a long strip
about 50 mm wide to be used at the bottom of the door. This is 2 to 3 mm
thick and is fastened to the door to keep air from leaking under the door.
Its flexibility lets it follow the variation of the floor as the door moves
over the floor. There are other shapes offered. Some seal the door
around the edge when it is closed. Others are intended for sealing
windows. In fact, in a few cases, these other shapes may be better than the
flat strip.
My experience is that samples of this foam are in perfect condition after
20 years. The foam has a smooth outer surface with pores inside. This can
be useful in applications in which something slides over the foam. The
foam would last longer when the pores are not exposed. You can shave the
smooth surface away in cases where it does more harm than good. The real
problem might be in finding this material. I suggest anyone who locates a
source should tell us the brand and source of supply. (I bought mine
decades ago and treat it like a treasure. Furthermore, I buy in a market
to which most of you have little access, and I have little access to yours
so I do not know what you can buy. Sorry!) Another problem is that I have
only brown and white. Black would be nice if it can be found. Silicone
will absorb some solutions and might let in dye, but will such treatment
shorten the life? I have no idea, but brown is probably not all that bad
for absorbing light, and better a tight brown seal than a leaky black one
or one with a short future.
Good luck.
Dr. Robert Mueller
Institut f�r Festk�rperforschung, FZ-Juelich
D-52425 Juelich, Germany
phone: + 49 2461 61 4550 FAX: + 49 2461 61 2610
email: [EMAIL PROTECTED]
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