Thus in non-casting bodies it is often not possible to achieve enough plasticity employing kaolin alone. Additions of ball clays, bentonites and other plasticizers are thus common where translucency and whiteness are not paramount. Kaolins are whiter and cleaner than other clays because they are mined near the site where they were weathered and altered from the parent rock. Kaolin ore is thus mixed with all kinds of other rocks and impurities which have to be separated using various wet and dry processing methods. For this reason kaolins tend to have much lower soluble salts than other sedimentary clays.
Kaolinite mineral has a much larger particle size than ball clay and bentonite type materials.
Thus kaolin and other clay material mixes often produce a good cross section of ultimate particle sizes. This imparts enhanced working and drying properties. Another advantage of the larger particle size of kaolins is that they are more permeable to the passage of water. Thus kaolins, especially the larger sized ones speed up casting rates in slurry bodies poured into plastic molds. Kaolins appear in almost all glaze recipes because they are white and thus color-neutral and they impart suspension properties to keep all the flint, feldspar, etc.