What Is Xylol? A Complete Guide to Uses, Properties, and Safety
eugene-a-xylol Xylol is the traditional name for xylene, a clear, sweet-smelling liquid hydrocarbon (dimethylbenzene, C8H10) and one of the most widely used industrial solvents in the world. If you have ever thinned oil-based paint, degreased machinery, or worked with printing inks, you have almost certainly come across it. This guide covers what xylol is, its properties, what it is used for, and how to handle it safely.
Key Facts About Xylol
- Also known as: xylene, dimethylbenzene, xylol solvent.
- Chemical formula: C8H10 (molar mass about 106.2 g/mol).
- Appearance: clear, colorless liquid.
- Odor: sweet, aromatic, solvent-like.
- Primary use: solvent for paints, coatings, adhesives, and cleaning.
- Flammability: highly flammable, flash point around 27-32 °C (81-90 °F).
- Water solubility: practically insoluble, so it floats on water.
What Is Xylol, Exactly?
Xylol is an aromatic hydrocarbon in the same chemical family as benzene and toluene. Chemically it is dimethylbenzene: a benzene ring with two methyl (CH3) groups attached. Those two groups can sit in three different positions on the ring, so xylol exists as three closely related forms, called isomers: ortho-xylene (o-xylene), meta-xylene (m-xylene), and para-xylene (p-xylene).
The xylol you buy in a hardware store or drum is almost never a single pure isomer. It is usually sold as “mixed xylenes”: a blend of all three isomers, often with a little ethylbenzene in it. That mixture works well as a solvent and costs less to produce than any isolated isomer.
Xylol vs. Xylene: Why Two Names?
“Xylol” and “xylene” name the same substance. Xylene is the modern chemical name used in most English-speaking countries. Xylol is the older, traditional name, still common in industry, in German-speaking regions, and on many paint and solvent labels.
Both names trace back to the Greek word xylon, meaning “wood.” Xylol was first obtained in the mid-19th century from the distillation of wood tar. Today it comes almost entirely from petroleum, through catalytic reforming, and from coal tar. The woodsy name has stuck for more than 150 years.
Chemical and Physical Properties
Exact figures vary a little between the three isomers. Commercial mixed xylol falls in these ranges:
| Property | Typical value |
|---|---|
| Chemical formula | C8H10 |
| Molar mass | About 106.2 g/mol |
| Boiling point | 137-144 °C (279-291 °F) |
| Density | 0.86-0.88 g/cm³ (lighter than water) |
| Flash point | 27-32 °C (81-90 °F) |
| Vapor density | About 3.7 (heavier than air) |
| Solubility in water | Practically insoluble |
| Miscibility | Mixes with most organic solvents (alcohols, ethers, oils) |
Two things matter in practice. Because xylol is lighter than water and insoluble, a spill floats instead of mixing in. Because its vapor is heavier than air, fumes sink and can collect in low, poorly ventilated spaces.
What Is Xylol Used For?
Xylol is a strong, relatively slow-evaporating solvent that dissolves oils, resins, and many synthetic polymers. Common uses:
- Paints and coatings: a solvent and thinner for oil-based paints, enamels, varnishes, and industrial coatings.
- Cleaning and degreasing: removing grease, tar, adhesive residue, and paint overspray from tools and surfaces.
- Printing inks and adhesives: a carrier solvent that keeps formulations workable.
- Rubber and leather processing: a processing solvent.
- Laboratory and histology: a “clearing agent” when preparing tissue samples for microscopy.
- Chemical feedstock: para-xylene is a raw material for making PET plastic and polyester fiber.
For painters and DIY users: Xylol is stronger and slower to evaporate than mineral spirits, which makes it useful for tough oil-based enamels and for cleaning up cured paint or tar. That strength cuts both ways. Test it on a small hidden area first, because xylol can soften or lift some plastics, sealants, and finishes.
Is Xylol Safe? Handling and Health Basics
Xylol is useful but deserves respect. It is flammable, and its vapors can affect the nervous system. Short-term overexposure to fumes causes headache, dizziness, and irritation of the eyes, nose, and throat. Repeated skin contact causes dryness and dermatitis.
In the United States, occupational exposure is regulated. OSHA sets a permissible exposure limit (PEL) of 100 ppm as an 8-hour average, and NIOSH recommends the same 100 ppm average with a 150 ppm short-term limit. Basic safe-handling practice:
- Use it only with good ventilation, or an organic-vapor respirator where the air cannot be cleared.
- Wear chemical-resistant gloves and eye protection.
- Keep it away from heat, sparks, and open flame, and store it in a cool, closed container.
- Never pour xylol down a drain. Dispose of it as hazardous waste.
Read the product’s Safety Data Sheet (SDS) before use. Exact hazards and first-aid measures depend on the specific formulation.
Did You Know?
The plastic in a typical clear water bottle owes its existence to one xylol isomer. Para-xylene is oxidized to make terephthalic acid, the building block of PET, the polyester used in drink bottles and clothing fiber. A solvent named after wood tar helps make some of the most common plastics on Earth.
Frequently Asked Questions
Is xylol the same as xylene?
Yes. They are two names for one chemical, and “xylol” is simply the older, traditional term.
Is xylol the same as paint thinner?
Not exactly. It can thin oil-based paints, but it is stronger and slower to evaporate than standard mineral-spirits paint thinner.
Does xylol dissolve in water?
No. It is practically insoluble, and being lighter than water, it floats on the surface.
Is xylol dangerous?
Its vapors can be harmful if you inhale a lot of them, and it burns easily, but it is safe to use with proper ventilation, gloves, and eye protection.