Not sure if this should go into Cafe Society or GQ, but…
Recently, I was listening to an old B-52s song called Legal Tender. The song is about counterfeiting.
One line goes
“So I fixed up the basement
with what I was working with
stocked it full of jelly jars
and heavy equipment”
Ok, I get the heavy equipment, but what does jelly jars have to do with counterfeiting?
The easiest way to spot a counterfeit bill is by feeling it. The best counterfeits use paper that closely matches what the treasury uses. This is almost impossible to come by … unless you use the actual paper that the treasury uses:
One technique in counterfeiting involves bleaching the denominations off small bills and then printing the higher denomination on–an improved method of “raising” the bill.
Without getting into the details, the bills are soaked in a bleaching solution to remove the desired information from the bill. A photocopier prints the new information on. The counterfeit now feels like the real thing and at a glance looks fine.
… and the jelly jars are used as vessels for the bleaching process.
Just to wrap up a major loose end there.
ACK!!!
Too much information alert!!!
We don’t wanna be telling people how to do illegal stuff! 
FTR: the source of my post was “How Stuff Works.com” if you can believe that!
I take it as a juxtaposition of usual basement equipment (canning jars) and secret, out-of-place items (heavy equipment).
Like “…working amid the spiders and 50 ton presses…”