Tensile Testing Hair

Tensile testing human hair is a common practice among manufacturers of various hair products, such as shampoos, dyes, and gels. It is important to be able to characterize the strength of hair to determine whether these products weaken or strengthen it. Similar to single strand textiles, there are many challenges associated with tensile testing of hair. Hair is normally very fine and often not long enough to be used in a cord and yarn style grip. In addition, hair is typically inconsistent, so it is important to test large sample sizes.

The challenges of performing this test:

• Specimen preparation
• Testing under non-ambient conditions

Our solution:

• Specimen preparation – Hair may be tested in single strands or multi-strands. When testing multi-strands, we recommend preparing the specimens in such a way that the individual hairs are bonded together. Adhesives, waxes, and other materials can be used to prepare specimens. When testing single strands, pieces of masking tape can be folded and adhered to each end of the specimen to serve as tabs. This helps make handling of the specimens much simpler while reducing the risk of failure at the jaw.
• Testing under non-ambient conditions – To simulate real-world conditions, hair can be tested in the BioPuls™ Bath which allows for testing in water up to 40°C, and can be fitted with submersible pneumatic grips with rubber coated jaw faces. 

A suitable system for testing hair would be one of our 3300 Series or 5900 Series electromechanical testing machines with Bluehill^® Universal software.