A ceramic term, it refers to clay, which has great plasticity and can be added to drier clay to make it more workable. Ball Clay and Bentonite are fat clays. Source: Ralph Meyer, "A Dictionary of Art Terms and Techniques"<br><br>A term used to describe paints which have a high oil content.<br><br>Describes an oil paint having a high proportion of oil.Also see fat over lean and lean.