Case study – Instrumental method development for the study of cosmetic powder compacts and brush interactions

Industry: Cosmetics

Internal R&D project

Project duration: 6 months

Cosmetic powders compact are usually handled with a brush or finger and the covering properties is commonly studied through sensory analysis.

We developed a scientific method based on mechanical and optical techniques for the study of powders compacts dynamic response to “brush-like” constraint and the understanding of brush/compact interactions. The system is implemented on a rheometer apparatus.

Steps for the development of an instrumental scientific method for the study of brush loading and compact application

RHEONIS holds combined expertise regarding instrumentation design, measurement protocols development and physical interacial sciences, that proved useful for this medium-term project.

  1. Literature study
  2. Functional analysis and brainstorming
  3. Mechanical design of a specific expertimental system on rheometry
  4. Preliminary testing
  5. Study of brush loading protocols and loaded-brush application on paper
  6. Development of image processing routines
  7. Adjustment and validation on various brushes
  8. Systematic study and correlations analysis
  9. Data interpretation and conclusions on the internal validity of the test
  10. Complementary trials and validation

Systemic stocks chart

Product & Ingredient 40%
Process & Application 70%
Measurement & Instrumentation 100%
Methods for Industry 100%

Scientific method for the analysis of powder compacts with respect to brush-like constraints


The testing system is mounted on a rheometer, allowing a fine control of applied constraints and measured responses. Interactions between the compact and the brush (loading and friction) can be quantified, but also the unloading of the brush on an application support. Combined mechanical and optical analysis allow various refinements of the interpretations, leading to a this method to be used as a predictive tool of sensory analysis of powders compact application.

The strengths of this innovative experimental approach

Apparatus and protocols validated

Implemented on rheometry systems (thus open for transfer)

Adapted to powder compacts study and application systems independently

Adapted for objectification of sensory analysis

If you have any question regarding this method or any issue with powders and compacts, feel free to contact us.

Last Updated on September 29, 2021 by Vincent Billot