Sulaiman - 12-7-2018 at 02:09
Yet again I have a partially used, solid, unusable cartridge of silicone sealant 
This time I opened it up:
The long tapered part can be cut into a series of small stoppers,
the large round rod may have a use ?
BUT
For some uses such as adapting ground glass to other materials it may not be too difficult to cast a re-usable stopper using fresh silicone rubber.
D.I.Y. could be cheaper and more versatile.
Just thought I'd air the idea here in case it is of use to anyone.
j_sum1 - 12-7-2018 at 02:44
I have three or four of these at present. Different products. I deliberately left them open after the last couple of jobs to see if I could get
something useful. I have seen them converted to stoppers on a yt video - on a lathe I think. But I can't remember where.
Sulaiman - 12-7-2018 at 03:13
I just cut a length of the large rod as it fits my 2l Erlenmeyer almost perfectly 
the Erlenmeyer that I just last month bought a white rubber stopper for 
Irrelevant:
I won the flask via eBay in April for £1.00, listed as
"60 corks from wine bottles and champagne bottles in decorative glass flask ",
Pyrex brand, even the base is hardly scratched
From the same seller I also won
5x 25ml volumetric flasks with ground glass stoppers for £1.00
and
2x 250ml glass bottles with ground glass stoppers for £2.60
- that my wife thought were too cute for chemistry so they are now in the kitchen
so I even got combined postage for £7.50
... a good hobby day
[Edited on 12-7-2018 by Sulaiman]
zed - 12-7-2018 at 15:28
I have applied this type of Silicone sealant, and the solvent in it, as I remember by smell, is Glacial Acetic acid.
So, it has good chemical resistance, but perhaps not to everything.