A gravimetic blender is an item of industrial equipment used in the plastics industry to accurately weigh two or more components and then mix them together prior to processing in an injection molding machine, plastics extrusion, or blow moulding machine. There are two types of gravimetric blender. Loss in weight Gain in weight (sometimes called a batch blender) A typical application of a gravimetric blender would be mixing virgin plastic granules, recycled plastic, and masterbatch (an additive used to colour plastics) together.