Use of specific solvents to coat materials for aesthetic and/or functional improvement has changed over the last hundred years. There are many different types of solvents used, and around 1920, the use of a specific group of solvents increased after it was discovered they were more functional than the previously used products. Prior to this time, n-butyl acetate was used as the primary coating solvent for industrial use. The introduction of a new class of chemicals allowed for a large void to be filled.
The glycol ether and glycol ether ester solvents filled this void. These are special in that they have a certain orientation of oxygen atoms in their chemical structure. These oxygen atoms are part of the alcohol (-OH) and ether (R-0-R) groups found in these chemicals. This makes for better coating solvents and allows for a perfect evaporation rate (how fast the coating will “dry” or evaporate, leaving the pertinent chemicals), which gives the solvent other good qualities, including the shine and protection it provides. This evaporation speed is much slower than the old standard of n-butyl acetate. Faster doesn’t necessarily mean better in the case of coating solvents. Finally, this class of coating solvents works well because they don’t have a very staunch smell, allowing for broader ranges of use.
A specific chemical containing glycol ether and/or glycol ether ester is used based on the specific coating needs of a product. One example is ethylene glycol monomethyl ether, which has an evaporation speed of 0.5 (20 times slower than n-butyl acetate). There are many other glycol ether/glycol ether ester chemicals, all of which only differ in the orientation or number of these oxygen-containing groups. The specific use for each was determined by experimenting to determine which would work best for a specific coating need. There are literally hundreds of coating solvents used today, but the introduction of chemicals containing these groups went a long way to replace the old and outdated standard of n-butyl acetate. This helped the industry move forward.