Xylene is an aromatic hydrocarbon, an organic compound created along with benzene and toluene by extraction and distillation in the petroleum refining process known as catalytic reforming. Xylene is also created from coal carbonisation in the manufacture of coke fuel. Xylene is mainly produced as part of the BTX aromatics. Xylene is used as a solvent. It is a common component of ink, rubber and adhesives. In thinning paints and varnishes, it can be substituted for toluene where slower drying is desired, and thus is used by conservators of art objects in solubility testing.