I'm not so sure those disks are made of rubber (and judging from Candace's 
original post, neither is she ... lotsa room between dried-out rubber and 
ceramic) ... especially the one on the left seems to show deteriorated 
ligneous fibers ...

... also, one of the things missing from all the published 
accounts/discussions/webpages is the EVOLUTION in the invention & 
development of the "ligneous disk" or "pog" type closure (mid-1880s to circa 
1910... into the standard "paper" or "cardboard" one of later years > 1910) 
... there were several different types of materials tried/used before 
settling on the standardized wax-impregnated paper/cardboard insert (that 
were still around during the childhoods of several subscribers on this 
list)... and your illustration (p3 - Fig 6) appears to be of the later 
cardboard type.

Candace's dates puts this artifact in the early range of the milk bottle 
caps, so the ones from that era are not gonna look like the prettily printed 
"paper" and "cardboard" versions, which are the ONLY ones apparently found 
illustrated anywhere. I've actually seen examples of (very badly 
deteriorated) rubber gaskets used under the bail-type metal milk bottle 
closures, but none looked anything like Candaces' artifacts. HOWEVER, I have 
seen (in junk shops, and private bottle collections, but not any museum 
collections I can remember) examples of what I construed as gaskets in the 
same context, that appeared to be rather similar to Candace's artifacts.

Anybody got a list of historic dairies (or bottlers ? might not be milk, but 
still could be a bottle closure gasket ... someone suggested ink ... and 
I've seen a LOT of ink bottles that came from school privies) in LA during 
that period? Any "M & Ms" or "HQs" ?

Bob

PS - by-the-way, that was a most excellent SHA article on Thatcher
~~~~~~~~~~~~~
"There is also an artificial aristocracy founded on wealth and birth, 
without either virtue or talents ... The artificial aristocracy is a 
mischievous ingredient in government, and provisions should be made to 
prevent its ascendancy."

- Thomas Jefferson (1743-1826)

>
> And NOWHERE in Lockhart's article does it mention RUBBER disks....which
> is my point - since Candace's disks are not wood nor fibrous.
> I really don't care how many times a milk lid was used...before
> breaking/becoming unuseable.
>