John Page writes about Copydex glue.  He states that he has "used
Copydex for a some time and can vouch for is suitability on disc
valves.  However, as it is basically a rubber solution..."

I wonder if Copydex is the same glue as Pliobond, here in the USA.
Pliobond is a rubber based glue, usually golden brown with some
material that settles.  When stirred, it becomes tan colored.  It has
a very strong solvent and is thinned with acetone.  It can be used as
a glue or contact adhesive or as a sealer.  John, please comment.

Craig Smith