Thinners are not interchangeable. Each is a carefully balanced blend of solvents designed to match a particular type of paint. Use the wrong one and you can get blushing, wrinkling, poor adhesion or a finish that simply never hardens.
Acrylic thinner
For acrylic lacquers and most 1K automotive paints. It is balanced for a smooth flow and a controlled, even dry. This is the everyday choice for spray-painting acrylic colours and clears.
Epoxy thinner
A stronger, slower blend made to thin two-pack (2K) epoxy and polyurethane coatings and high-build primers. It also cleans equipment after using these tougher products. Do not use it to thin standard acrylic — it is too hot.
All-purpose / multi thinner
A general-purpose thinner for enamels, cleaning equipment and removing fresh overspray. It is the handy all-rounder for the shed, but for critical finishes you should match the dedicated thinner to your paint.
Gunwash
Not a thinner at all — it is an aggressive cleaning solvent for flushing spray guns and equipment between colours. Fast and cheap, but never use it to thin paint that is going on a panel.