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Expert has expertise in applied research and product development combining the fields of rheology and colloidal chemistry. He is experienced with the formulation and rheological classification of dyes and pigments. He has investigated the rheological properties of magnetic and carbon black pigment suspensions as they effect coating processes (including knife, gravure, 3-roll, and slot coating). Expert has also conducted applied research on consumer products such as suspensions, dispersions, surfactant- and polymer-thickened cleaning products, pastes, and foods (particularly salad dressings and sauces). He developed a rheological technique for measuring the phase inversion temperature of nonionic surfactant/oil/water emulsions and for tracking phase changes of surfactant systems. This is the only technique available that can follow both a cloud point and a lamellar phase transition in dilute surfactant solutions. He has established several rheological laboratories and purchased the associated equipment.

Expert served as an expert consultant to product development groups on issues of stability, phase behavior, viscous and wetting behavior, and processing needs. In conjunction with product development, he ascertained the effects of soluble polymer binders, surfactants, lubricants, and processing conditions on the stability and coatability of metal oxide and metal dispersions. His work in this area has led to improved quality control and yields by controlling the rheological properties of the magnetic dispersions.

Much of Expert's career has concentrated on dispersions (solid-liquid, liquid-liquid), both concentrated dispersions and low volume-fractions (such as inks). Because of his earlier work with laboratory formulation and processing of flame-retardant coatings, Expert has gained strong working knowledge of dispersion equipment and techniques. He developed a 3-dimensional dynamic rheological technique to predict the long-term stability of concentrated suspensions. He also discovered and patented surfactant mixtures with extensional properties useful for reducing misting in spray applications.


While most of the extensional viscosity work has been done on plastics and extruded melted polymers, much of Expert's work has centered on low-viscosity fluids (such as cleaning sprays) and especially on salad dressings, where he has used the extensional viscosity measures to correlate mouthfeel. Expert believes this area remains relatively unexplored because of the difficulty of the experiments and lack of knowledge as to its importance.

Expert's work has taken him to the extremes of rheological measurement, from fluids with viscosities close to water, to pastes with viscosities in the millions of centipoises. His range of experimental experience varies according to the material and the properties of interest, but he has run oscillatory experiments as well as creep, viscosity, relaxation, and extensional tests and combinations of these to mimic production or processing conditions.


Because of the various materials he has studied and the differing requirements of each, Expert has gained extensive experience comparing rheometers of the major rheological equipment suppliers. He is familiar with the leading equipment designs, controlled strain and controlled stress rheometers, as well as extensional rheometers. He is also familiar with their strengths and weaknesses, especially for research versus quality control needs.

Expert understands how the viscosity of a material can be controlled by its temperature, concentration of actives, or by additives that can interact with the mobile solvent phase or with the particles in a dispersion. He has improved production processes by indicating where the viscosity was most useful at a particular temperature, or by the addition of thickeners (with and without gel forming properties). The colloidal chemistry can also play a huge role (as in mineral oxide dispersions) where precipitation and thickening can occur at the right pH. By determining the rheology as a function of pH, Expert was able to help manufacturing personnel understand the process of dispersing these oxides and how to control the viscosity.