With apologies to Robert Duvall, I really do love the smell of shoe repair shops. It was only after I became a chemist that I realized just how nasty much of the stuff really is.
The main contributer to the great smell of a shoe shop is Barge cement. Wayne called it “Barges”. I have no idea why he made it plural, but to this day I still need to look at the label (or google it if I’m writing a blog) to see the correct name. We literally used it by the gallon, and I still use it for my leather work. It is the only thing available to glue on soles of shoes that are not also sewn. (It is still used to glue soles that are sewn, because if they aren’t glued first, your shoes will squeak like crazy when you walk.) We keep it in “glue pots”, and each person in a shoe repair shop will typically have his own that is close because it is used so much. The glue pots get a lot of drips on the outside, resulting in a thick yellow-orange-brown mass that grows over the pot and brush handle. When it gets too bad and there is a slow time in the shop, you can pull the mass off and clean the pot. If it goes too long, you need a knife or heel pry tool to work it off.
The glue also gets all over your hands, and to this day I love to pick at it. A shoe repairman does not have clean hands; leather dye and shoe polish are hard to remove, and there are always bits of dried glue stuck to various places.
The glue is generally used near one of the main machines in a shoe repair shop, the big and noisy grinder/finisher. This is where soles are heals are first sanded down and then finished and where all shoes are polished. We had a policy at Tip Top that every shoe got at least a quick polish when it came in for repair, even it is was just a small sewing job. People really noticed it and appreciated it. I polished A LOT of shoes.
When the grinder is on, it has ventilation, and at least some of the nasty fumes from the Barge get pulled out of the (small) room. However, when it isn’t on, the fumes tend to accumulate. Over the years, I worked in 3 different shoe repair shops and visited many more, and I don’t think I ever saw anything that would pass as good ventilation in a chemistry lab. Toluene is one of the main ingredients of Barge cement, and it differs from benzene by just one methyl group (a carbon with 3 hydrogens). Benzene is a carcinogen with several possible mechanisms of causing cancer. Some chemicals that are similar to benzene will intercalate into DNA, because the 4 bases in DNA (A, T, G, C in case you forgot your basic biology) are aromatic and have similar chemical properties to benzene. If a chemical intercalates into DNA, it can lead to a mutation, because the cellular machinery that copies the DNA won’t be able to read it correctly. There are many different ways to get cancer, and benzene likely has other mechanisms. Even though toluene differs from benzene by just a few atoms, it doesn’t appear to have the carcinogenic properties of benzene [see the comment below from an alert reader!], but toluene can cause severe neurological problems and is also very flammable. Nasty stuff!
A science lab in a major research university would likely be shut down if they used toluene the same way that shoe repair shops use it on a daily basis.