Fluid coke consists of spherulitic grains with a spherical layer structure and is generally less graphitizable than delayed coke. Therefore, it is not suitable as filler coke for polygranular graphite products and is also less suitable for polycrystalline carbon products. Because of its isotropy it is less suitable to produce an anisotropic synthetic graphite. All cokes contain a fraction of matter that can be released as volatiles during heat treatment. This mass fraction, the so-called volatile matter, is in the case of fluid coke about 6 wt.%.