Trefor Evans

Institute Fellow, Director of Research


Dr. Trefor Evans has worked in the Hair Care industry for almost 25 years. The majority of this time was spent as a scientist and manager in the product development labs of large consumer goods companies (Unilever, Helene Curtis); he joined TRI in 2007 where he served as Director of Measurement Services for 5 years. He now holds the title Institute Fellow and is responsible for TRI’s Research Program.
Dr. Evans is highly active in the hair care industry through many working relationships with companies of every shape, size and background. He is a regular presenter at International hair conferences and has been an invited speaker at many technical meetings and symposia. Most recently he served as Chairman of the 6th International Conference on Applied Hair Science in Princeton, NJ. He has published numerous articles in trade magazines and the scientific literature and is co-author and co-editor of the book “Practical Modern Hair Science” by Allured Books. He writes a regular column on hair testing and hair science for Cosmetics and Toiletries and serves on the magazine’s Scientific Advisory Board. He is also a member of the Expert Reviewing Panel for the Journal of Cosmetic Science.
Dr Evans possesses a Ph.D. in the area of physical analytical chemistry and has spent his career using instrumental testing approaches to support the development, launch and maintenance of many internationals cosmetics
products and brands. Such approaches also continue to be at the heart of fundamental research programs that have twice been awarded by the Society of Cosmetic Chemists. He moderates and teaches TRI’s Hair Science and Hair Claims Courses which have been held in both the US and Europe. He also lectures on Hair Science and the Hair Care Industry as part of Master of Business and Science program in Personal Care Science at Rutgers University, and has instructed at educational events organized by the Society of Cosmetic Chemists. 
Recent Publications

T.A. Evans, Body Talk: Defining Volume, A Technical Dissertation on Hair Body and Volume. Cosmetics & Toiletries, Vol. 133(6), 48-55, June 2018

T.A. Evans, New Ideas on Hair Breakage: Mending Existing Flaws. Cosmetics & Toiletries, Vol. 132(8), 46-53, September 2017
T.A. Evans, How Damaged is your Hair? – Part 3: Better defining the problem. Cosmetics & Toiletries, Vol. 132(7), 58-67, July/August 2017
T.A. Evans, How Damaged is your Hair? – Part 2: Internal Damage. Cosmetics & Toiletries, Vol. 132(6), 36-45, June 2017
T.A. Evans, How Damaged is your Hair? – Part 1: Surface Damage. Cosmetics & Toiletries, Vol. 132(4), 38-48, April 2017
T.A. Evans, A unifying theory for visualizing the causes of hair breakage and subsequent strategies for mitigation. Journal of Cosmetic Science, 68, 137-140, Jan/Feb 2017


T.A. Evans, The Perplexing Topic of Hair 'Type': How Do We Classify Hair? Cosmetics & Toiletries, Vol. 131(8), November 2016.


T.A. Evans, A Sunny Proposition: The Effects of Sun on Hair. Cosmetics & Toiletries, Vol. 131(8), August 2016.


T.A. Evans, Nonreactive Paths to Internal Changes: Modifying Hair’s Structure from the Inside, Part 2. Cosmetics & Toiletries, Vol. 131(6), June 2016


T.A. Evans, Modifying Hair’s Structure From the Inside, Cosmetics & Toiletries, Vol. 131(3), March 2016

T.A. Evans, Coiffed Conundrum: Equating the Measurement of Hair Shine, Cosmetics & Toiletries, Vol. 131(2), February 2016

T.A. Evans, Beating the Damaging Effects of Heat on Hair, Cosmetics & Toiletries, Vol. 130(5), June 2015
T.A. Evans, Defining and Controlling Frizz, Cosmetics & Toiletries, Vol. 130(4), 46-53, May 2015
T.A. Evans, Quantifying Hair Color Fading, Cosmetics & Toiletries, Vol. 130(1), 30-35, January/February 2015
T.A. Evans, Hair as a Test Substrate, Cosmetics & Toiletries, November 12, 2014
T.A. Evans, Quantifying the Performance of Hair Styling Products - Part 2, Cosmetics & Toiletries, September 2014
T.A. Evans, Quantifying the Performance of Hair Styling Products, Cosmetics & Toiletries, Vol. 129(5), 46-49, June 2014
T.A. Evans, Measuring the Water Content of Hair, Cosmetics & Toiletries, Vol. 129(2), 64-69, March 2014
T.A. Evans, Measuring Hair Strength, Part 2: Fiber Breakage. Cosmetics & Toiletries, Vol. 128(12), 854-859, Dec 2013
T.A. Evans, J.M.Altland, R.Burch and J.Horsager, Glycolic Acid, No Longer Just for Skin – Changing the Internal Properties of Hair. Cosmetics & Toiletries, Vol. 128(11) 816-820, Nov 2013
T.A.Evans, Measuring Hair Strength, Part 1: Stress-Strain Curves. Cosmetics & Toiletries, 128(8) 590-594, Aug 2013
T.A. Evans, Consumer vs. Scientific Language: Relating In vivo to In vitro. Cosmetics & Toiletries, Vol 128(5), 300-304, May 2013
T.A. Evans, Evaluating Hair Conditioning with Instrumental Combing. Cosmetics & Toiletries,Vol 126, No 8, Aug 2011
T.A. Evans, K. Park, B. Yang, M. Kadir, S. Herrwerth and B. Gruening, Quantifying Benefits of Conditioning Treatments on Hair Breakage. SPC Magazine, 51-54, November 2010
T.A.Evans and K.Park, A Statistical Approach to Hair Breakage. II. Repeated Grooming Experiments. Journal of Cosmetic Science, 61, 439-455, Nov/Dec 2010
T.A.Evans, Fatigue Testing of Hair – A Statistical Approach to Hair Breakage. Journal of Cosmetic Science, 60, 599-616, Nov/Dec 2009


T.A. Evans, Tress Stress: How the Environment Affects Hair. Cosmetics & Toiletries, Vol. 134(3), 32-42, March 2019

T.A. Evans, Quantifying Visual Aspects of Hair. Cosmetics & Toiletries, Vol. 133(10), 36-44, November/December 2018

T.A. Evans, Your Hair on Acid: The Influence of Carboxylic Acids. Cosmetics & Toiletries, Vol. 133(9), 40-48, October 2018


Books and Chapters
Ed.Trefor Evans and R. Randall Wickett (2012), Practical Modern Hair Science, Allured Books
Evans, Trefor (2010), Ed. J.W. Fluhr, Practical Aspects of Shampoo and Conditioner Testing in Practical Aspects of Cosmetic Testing, Springer Press

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