[NHCOLL-L:2263] Taping

[Paul Callomon]

Re: sealing alcohol jars with tape - my 10 cents' worth:

My predecessor as collections manager spent a great deal of time wrapping plumbers' tape (PTFE tape) around the outside of every one of our roughly 20,000 alcohol jars. I can't say whether this did anything to slow evaporation, but in many cases it did successfully hide signs of physical deterioration - cracks in Bakelite lids, rusting in steel ones - until it was too late. 
Wrapping plumbers' tape around the threads before closing the jar is not likely to help at all, as this tape is intended to 'smear' and close gaps in fine pipe threads with breadths in the order of microns. The threads on glass jars are so coarse that the tape will not bridge the gaps. 
We too now use foam-backed Teflon liners in ABS lids, and this seems to work pretty well. I think it's a better idea to spend a bit more money on preventing vapor getting across the sealing face in the first place than on wrapping tape around the outside of jars.
Incidentally, we have a large number of old bail jars (Atlas Wholefruit and so on) that have held up just fine for over 80 years. The alcohol in most of them is still in the 65-70 per cent range, which is pretty good considering that it started at 70 before water-bearing flesh was placed in it. The natural rubber seals have hardened right up, but in the majority of these jars there is no sign of leakage.

PC





Paul Callomon
Collections Manager
Malacology, Invertebrate Paleontology and General Invertebrates
Department of Malacology
Academy of Natural Sciences
1900 Parkway, Philadelphia PA 19103-1195, USA
Tel 215-405-5096
Fax 215-299-1170
Secretary, American Malacological Society
On the web at http://erato.acnatsci.org/ams/