Reference point
Smell a new tyre or a pair of just-bought rubber sandals.
Do this before you read on. An entry only works when you have just smelled the thing.
Pungent, with a clear sulphur note, a faint sweetness and a layer of smoke underneath.
The sulphur note is no accident — sulphur is what turns rubber into rubber. You are smelling the manufacturing process itself.
Natural and synthetic rubber give two different smells, and telling them apart is a skill of people in the trade.
How to smell it
Smell a new tyre, then an old one that has been driven for a few years — the sulphur has dropped a great deal and been replaced by a note of road dust. If you can find fresh latex, even better: it has almost none of that note.
Why this one is hard
Because it always appears in the setting of shops and vehicles, so it gets lumped into a general “repair-shop smell”.
Scientific note
Vulcanisation uses sulphur to form bridges between polymer chains, turning soft latex into a durable elastic material. Excess sulphur and the sulphur compounds formed in the process keep escaping from the material for months afterwards. That is the source of the characteristic note.
In Vietnamese life
Vietnam is one of the world’s largest producers of natural rubber, and the rubber plantations of the southeast smell of fresh latex, entirely different from finished rubber. Very few people have smelled both.