First off, there is a difference between a thinner and a solvent.   A solvent dissolves things.    A thinner thins things DUH (reduces the solids and alters the viscosity).  What makes thins even more confusing is they way they name things.   Lacquer thinner both dissolves and thins (because it contains both solvents, co-solvents, and thinners).  Paint Thinner thins varnishes, but dissolves waxes.    But anyway,  (chemistry lesson)

 

1. Distillates generally of petroleum.   Common ones are mineral spirits and naphtha.  Less commonly used ones are kerosene, xylene (xylol), toluene (tolulol), benzene  (a carcinogen), and benzine, and even turpentine (a distillate of pine sap).  These have different evaporation rates, oiliness, and smells.  These generally thin (oil-based) varnishes and are in some lacquer thinners.  Xylene will soften cured water-borne finishes.  Most of these will dissolve waxes, oils, and some adhesives.  d-Limonene is a distillate of citrus rinds; it's found in some cleaners/polishes/degreasers/adhesive removers.

 

2. Alcohols and Ketones.   Alcohols include ethanol, methanol, and isopropyl.   "Denatured alcohol" is ethanol (grain alcohol - everclear booze) with enough methanol (wood alcohol) added to make it poisonous to drink (and so it does not need to be taxed as booze).   Chemically, a ketone is an oxidized alcohol.  Common ones are acetone and MEK.   Alcohol is a solvent for shellac and alcohols and ketones are often part of lacquer thinners.

 

3. Glycol Ethers are a large class of chemicals and are in water-borne finishes.  Two major classes are ethylene glycol or propylene glycol.  They soften and make sticky the large resin molecules.   As the glycol ethers evaporate the resin molecules bond together.  Cellosolve is a trademark for a glycol ether.

Thanks, I learn something from each of these posts!