I think you maybe right, even though Acetone is a standard thinner it may be that the more common/cheaper chemical is Cellulose.
However, I grabbed this off of another forum and looks quite interesting: which can be read in its entirety here:
what's in cellulose thinners?
Q:
i've bought a couple of the cellulose thinners from halfords before, fine, they're convenient. but this time i decided to get a 5 litre drum of it. went to the paint shop, and the guy said it was fine for cleaning and spraying.
the halfords one smells quite nice lol and is perfectly colourless
this new one is rank, and slightly yellow. its says on the bottle 'contains toulene'. is toulene the main thing in cellulose thinners?
A:
Toluene, also known as methylbenzene, or Toluol, is a clear water-insoluble liquid with the typical smell of paint thinners, reminiscent of the related compound benzene. It is an aromatic hydrocarbon that is widely used as an industrial feedstock and as a solvent. Like other solvents, toluene is also used as an inhalant drug for its intoxicating properties; however, this causes severe neurological harm.
Toluene reacts as a normal aromatic hydrocarbon towards electrophilic aromatic substitution.[3][4][5] The methyl group makes it around 25 times more reactive than benzene in such reactions. It undergoes smooth sulfonation to give p-toluenesulfonic acid, and chlorination by Cl2 in the presence of FeCl3 to give ortho and para isomers of chlorotoluene. It undergoes nitration to give ortho and para nitrotoluene isomers, but if heated it can give dinitrotoluene and ultimately the explosive trinitrotoluene (TNT).
I think the fan should run constantly while the heating process is in effect !