A superior powder form of a metallic soap for enhancing the properties of an invert emulsion drilling fluid may be prepared by a dry process saponification reaction. The process includes mixing a source of metal cations with the product of a Diels-Alder reaction of dienophiles with fatty acids and/or resin acids and allowing the mixture to react. Heating the mixture increases the rate of reaction. The solid product is ground to form a powder. The properties of the drilling fluid that may be improved by adding the soap include filtration control, fluid loss control, emulsification and emulsion stability, and electrical stability.