Mainly I have standard orange rubber bungs and tubing, the kind which is typically used in laboratories for bunsen burners and vacuum lines etc. Some
of the tubes in particular have turned to resembling a clay pipe.
I have searched online and found various suggestions, such as treating with a warm 5% NaOH solution; rubbing on glycerol; oils; adding a plasticiser
from an oil solution.
If someone has experience with this issue, I would be pleased to receive any advice. Preferably I would like to 'repair' the rubber, rather than just
make it temporarily supple.Praxichys - 13-8-2014 at 10:39
I have a whole pile of "fossilized" erasers that were given to me many years ago by my high school. They are about as useful as small bricks now, but
I have held on to them in the event that I ever found a way to render them supple again.
I am hoping it is not a consequence of continuous and slow vulcanization over time. In that case, the change may be irreversible.forgottenpassword - 14-8-2014 at 02:32
Having looked into it a bit more, I think that adding a plasticiser will be the best method. This doesn't seem to be a topic of much interest.Texium - 14-8-2014 at 05:22
I'm definitely interested, because I have quite a few
crusty old stoppers myself, but I don't know anything about fixing them either.vmelkon - 14-8-2014 at 07:05
Plasticized PVC is pretty good.
If you look at some door frames and windows frames made of PVC, you will notice that it was coformed with some cold barrier that looks like rubber.
It isn't rubber. It is plasticized PVC.
http://www.pvc.org/en/p/plasticisers
"The most common are: diisononyl phthalate (DINP), diisodecyl phthalate (DIDP) and di-2-ethylhexyl phthalate (DEHP, sometimes also referred to as
DOP)"
I imagine the trick is to heat this stuff at sufficient temperature and dip the part in. The small molecules get in between the large polymer
molecules.
If you don't have those chemicals, perhaps you can try with glycerol, like you wrote.forgottenpassword - 14-8-2014 at 08:16
Vogel's 3rd recommends glycerin, perhaps try that first...forgottenpassword - 15-8-2014 at 10:46
Thanks. First place I looked - must have missed that.
Tried a small piece of tubing today. Broke cleanly before any treatment. After soaking in room temperature glycerine for about 8 hours was still
stiff, but could be bent with some gentle pressure. Longer soak necessary, but definite improvement - temporary or permanent I don't know.
Will try putting a rubber bung to soak in warm glycerine, and see if it remains supple after washing and drying.
