The HAIR COMBING RIG (A/HCR) has been developed to assist manufacturers in the development of more effective conditioning agents.It is well known that conditioning shampoos and hair conditioners are used to provide a variety of benefits to hair: they reduce the combing force, enhance the gloss, confer smoothness and antistatic properties and they improve the manageability of the hair.
Various types of benefit agents including cationic surfactants, polymers, emollients, and special compounds such as vitamins, UV filters, etc. contribute to cosmetic properties.
For example, silicones are insoluble oils that are commonly use as conditioning agents for hair as they can effectively reduce combing friction of hair and provide a soft, smooth feel and a shiny appearance. UV inhibitors are becoming more commonly used in shampoo formulations for preventing damage and hair colour fading.
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| Comparison of serum- and fixative-treated hair tresses |
The Hair Combing Rig is positioned on the texture analyser and the supported length of hair is held vertically, near to the comb. When instructed, the arm of the texture analyser brings the comb down through the hair, recording the necessary force as it moves. At the end of a stroke, the comb is mechanically disengaged and moves back to its starting position to begin the next combing cycle.
Some more information on this fixture:
Combability Testing: Wet Combability
One of the methods that are used to determine conditioning efficiency is combability. Wet combability is measured under controlled conditions using an objective tensile method, in which a texture analyser measures the combing force required to pull a wet hair swatch (or tress) through a comb. It is usually necessary to first detangle and then to tangle hair in a controlled and reproducible way before the measurements.
Blank hair swatches containing only water are run through the test to establish an initial benchmark. Then, the test solution is applied to the same swatch and measured for combability again to determine if, for example, the conditioner provides any improvements in combing. The maximum force to comb and the total work done are taken as comparative measures.
A reduced combing force and work (usually calculated in percentage terms of a treated hair tress compared to the same tress treated with a blank formulation, i.e. no polymer) implies easier wet combability associated with the removal of entanglements of the hair fibres and can therefore be used to substantiate claims of improved manageability.
In practice, the hair is brought to a “wet state” by spraying the swatches (e.g. virgin Asian hair vs. Caucasian hair) with water until a water regain of 60% weight is achieved. The initial force necessary to comb the hair swatch is measured on a texture analyser under climatised conditions (20ºC, 65% rh). The hair swatches can then be treated with e.g. conditioners and irradiation, before comparing the effect of the treatment to the initial combability measurement.
To compare, the hair swatches are washed with a standard shampoo, dried and climatised for 24 hours. The hair is then brought to a “wet state” by spraying with the water until a water regain of 60% by weight is achieved. The final force necessary to comb the hair swatch is measured with the texture analyser at 20ºC.
When assessing combability a researcher may typically need to perform the comb force test for a certain number of combing cycles in order to obtain a complete assessment of the effects of a treatment with repeated combing. A combing test can be set up in such a way that the combing fixture is positioned onto the texture analyser and the supported length of hair tress held vertically near to the comb. The arm of the texture analyser is then instructed to move downwards and in doing so combs through the length of hair.
If repeated combing is required, it would be incorrect to continue combing upwards with the hair tress in position (to have the comb return to its starting point) and then comb downwards again.
This testing issue has been resolved by Stable Micro Systems by the employment of a mechanical method of disengaging the comb at the end of its combing stroke. The comb fixture then returns to its starting position away from the hair tress. At the starting position the comb is mechanically returned to its combing position within the hair ready to commence the next combing cycle. This can be continued for as many cycles as is required within one test to complete the assessment.
Combability Testing: Dry Combability
The combing force evaluation is equally effective for assessing combability of dry hair. All modified hair types (e.g. chemically treated (bleached), delipidised (by solvent extraction), and polymer treated hair) show an increase in dry combing forces as quantified by combing measurements. The combing work (g cm) and force as a function of tress distance would be substantially higher for all modified hair types compared to that of virgin hair and therefore this method can be used to assess, for example, the effect of addition of smoothing serums to dry hair.
We can design and manufacture probes or fixtures for the TA.XTplus texture analyser that are bespoke to your sample and its specific measurement.
Once your measurement is performed, our expertise in its graphical interpretation is unparalleled. Not only can we develop the most suitable and accurate method for the testing of your sample, but we can also prepare analysis procedures that obtain the desired parameters from your curve and drop them into a spreadsheet or report designed around your requirements.
For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.
The TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is
available to measure and analyse the textural properties of a huge range of
food products. Our technical experts
can also custom design instrument fixtures according to individual
specifications.No-one understands texture analysis like we do!
To discuss your specific test requirements click here...
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