Water based acrylic. Use 20%-30% MMP thinner to 1 part paint. (2-3 drops thinner to 10 drops of paint thinner). Mission Models paint thinner is very powerful and only the smallest amount of thinner is needed. In the mixing cup your reduced paint will appear thicker than what you may be used to: this is normal. MMP paint will dry smooth, thin and level. It will not hide the finest of details. Mixed properly you will find a beautiful opaque finish which requires minimal coats. TIP: add one or two drops of MMP Polyurethane Intermix for additional reduced tip dry when spraying straight from the bottle. MMP Poly increases flow, lowers drying times, gives added leveling , increases blending when brush painting, improves durability and adds a slight eggshell finish. As modelers we highly recommend this as an option. Polyurethane Intermix should be mixed 1-2 drops to 10 drops of paint. All paint should be stirred not shaken in the paint cup. 1 oz bottle (29.57ml)