It's a solvent for a prototype.・It's an essential element used to adjust the viscosity of a paint solution, to clean air brushes and pens. There are special types of paints, such as lacquer, acrylic and enamel systems, that make the finish even and bring out a beautiful gloss and color. It can also be used to wipe where you've been over-painted or exposed, so it has a lot of potential for widespread consumption, so large-scale applications are popular.