On Feb 8, 6:03*pm, " Moonraker" wrote:
wrote in message

...
On Feb 8, 4:57 am, pantagruel wrote:

by making jars I mean especially how the lids of jars are threaded,
tools for doing so.

Thanks,
Bryan Rasmussen

I believe that molten glass is poured into molds that have the threads
and any raised logos already made into the mold.

volume produced jars are more likely pressed?

Bryan,

All jars with threads are made in molds (old-style "moulds"). The
mold provides all of the shape and features of the finished product.
A gob of glass is placed in the mold and the molten glass is pressed
into the sides of the mold by air and/or with an insert.

Liz Scott, Manager
Glass Factory Directory of North America
http://www.glassfactorydir.com/Education.html