Texture Analysis in Action 2: Nail Polish Adhesion Rig

The Nail Polish Adhesion Rig and method have been developed by Stable Micro Systems to provide the solution to this assessment requirement. 

During the polish drying time test, a channel 20cm long is filled with polish to a depth of 0.5 mm and wiped level using a glass rod. 

At this point a timer within the Exponent software test sequence is started. This depth is representative of a typical coat of polish on a fingernail; a depth of 0.5mm dries to approximately 0.2mm. This channel is seated on top of the Adhesive Indexing System that has ten detents and so ten test sites are available by simply sliding the platform along. 

A 1 inch detented ball probe is used for the tests, which can be turned to allow a clean test site without either replacing the probe or the requirement to clean and dry the probe between tests. This is used to perform an adhesive test at the first test site. A force of 750g is held for 5 seconds to allow a bond to form. 

The probe is then quickly withdrawn, breaking the nail polish bonds, and the force to do this is measured. The channel is moved along to the next site and the test repeated. A set of ten tests are performed in this way with pre-set time delays between the tests. Tests are performed over the whole drying period of the polish. 

Several measurements can be made from the force-time graph: 

1) The maximum force needed to withdraw the probe from the sample is a measure of the strength of the bond or the adhesiveness of the polish. The initial wet polish has a very low adhesive force. As time passes the stickiness increases until it peaks, then drops off. The polish has been found to be touch dry after the peak. 

Typical graph from Nail Polish
Adhesion Rig test

2) Similarly, the work of adhesion is the total energy required to pull the probe from the polish each time and is represented by the area under the force-distance graph for each test cycle. 

3) Softness is defined as the distance the probe is required to sink into the surface of the polish before the force reaches 25g. The softness decreases with drying time until it reaches a plateau, at which point the polish is touch dry. 

4) Stringiness is the distance the probe withdraws while the polish is still adhered.
The series of adhesion tests is automated by a unique test sequence developed in Exponent software, with parameters such as the delay between tests, the number of repeats, applied force and holding time adjusted by the user if necessary. 

Additionally, an analysis macro is available to measure the above four properties across all repeats at the press of a button. With the addition of instruction messages in the sequence this provides a user-friendly solution for this type of product testing. 

Exponent software offers a whole series of application studies for the testing of cosmetic products. Download it to have instant access to the methods and project files to start testing your cosmetic products.


Contact Stable Micro Systems today to discover the full range of Texture Analysis solutions.

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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!

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