"T i m" wrote in message
...
On Thu, 21 Aug 2008 22:32:59 +0100, "Spamlet"
wrote:


See what you have around. Note that swelling may take several hours, but
check at first that your sample is not going to turn into a sticky mess.

Right, so far I've soaked the rubber valve for several hours in:
lighter fluid, white spirit and panel wipe with no affect at all?

If that means anything to anyone (from their likely chemical content)
what sort of things should I try next please?

All the best ..

T i m

Not sure what the 'panel wipe' is, but all the others are 'non-polar'
paraffin solvents. So you now move on to the other kinds - your ketones like
acetone, and mixtures like 'cellulose thinners'; and the chlorinated
compounds. If you don't have any chlorinated solvents in your rather
enviable list of what you have to hand, getting some methylene
chloride/dichloromethane containing brush cleaner may be as near as you can
get in 'off the peg' availability. Dichloromethane is pretty much the most
aggressive of the 'off the peg' compounds when it comes to dissolving
organics, which is why it is first choice in paint stripping applications,
where cost and fumes are not an issue. This would have been my first
suggestion if I wasn't concerned that you might simply dissolve the thing
before you could get it out of the solution!

Pencil 'rubbers' seem to be silicone based these days, if the smeary mess
many of them leave on the paper is anything to go by. I'm afraid, I don't
know enough about these to know if they can be swelled, but, if this is what
you do have, then you ought to be able to mould a new piece as someone
suggested earlier. Sorry if my suggestions have delayed your 'final
solution'.

Cheers,
S