Abstract

The effective application of rheology helps to speed the formulation of personal care products to a profitable conclusion. Here John Duffy, Product Marketing Manager for Malvern Instruments, examines how rheology can be used to quantify key aspects of product performance such as texture and ease of application.

INTRODUCTION

Developing a detailed specification that defines and safeguards product quality through development and into manufacture is an essential aspect of product formulation. For personal care products quality is often defined by a range of functional and sensory attributes, some of which may be easily measured - such as color - and others which may not. Visual or textural appearance and ease of application exemplify properties in this second category. Ultimately these attributes are assessed subjectively via user feedback, but relying on such information to guide formulation is somewhat impractical, particularly in the early stages of product development. Metrics that reliably correlate with product performance are therefore essential.

Rheology adds value in product formulation and benchmarking studies by providing these product performance metrics. The resulting data can be used either to replicate the quality of an existing product, to compare formulations or competitor products, or to develop a specification for a brand new product. Rheological properties such as viscosity, yield stress and viscoelasticity can be used to determine ho ...