Our professional additives are used to permanently adjust the chemistry and character of your acrylic color. Made without acrylic binders, these four formulas are very different to the rest of the mediums family. Most mediums contain high proportions of acrylic resins, but additives do not. Instead, they offer unique changes - from the aerated, sponge-like effects of Liquithick, to Flow-Aid's water-like fluidity which makes it ideal for watercolor techniqes, staining and flow art. When you don't want to change your colors opacity levels but find you need longer working time, Slow-Dri Additive - in gel and fluid formats - helps you extend it by 40%.