Grades and Purity: What the Labels Mean

Not all xylol (xylene) is the same, and the difference is grade. Two cans can carry the same name yet differ in purity, water content, and which isomers they contain, and that can matter for the job and the price. Here is what the grade labels mean.

The common grades, from most general to most refined:

• Technical or commercial grade: ordinary mixed xylenes, the standard solvent grade for paints, coatings, and cleaning. Good enough for almost all trade and DIY work.
• Reagent or laboratory grade: higher purity with tighter limits on water and impurities, used where the chemistry has to be clean.
• Histological grade: a purified grade sold for laboratory tissue processing, where residue would spoil the sample.
• Single isomers: ortho-, meta-, or para-xylene isolated on their own, sold as chemical feedstocks or for specialized use, and priced well above the mixed grade.

For most buyers, technical-grade mixed xylenes is the right and economical choice; paying for lab or isomer grades buys purity you will not use. The place to confirm what you are getting is the Safety Data Sheet, which states the composition and any specification. If a job is sensitive to water or to a particular isomer, check the grade before you buy, because the label name alone will not tell you.