Performance Testing
Test and measurement methods:
For particularly practical verification of product effectiveness, bpc specialities carries out various test and measurement methods in the course of performance testing.
In vitro and in vivo measurement methods
The in vitro test methods are performed on standard strands or on harvested subject hair. The standard strands are human hair. This is bleached by an osmotic process in order to preserve the structure of the cuticle as far as possible. This ensures maximum reproducibility of the hair matrix in terms of hair quality.
In order to make our tests as practice-oriented as possible, we focus on measurement methods that can be performed both in vitro and in vivo. The aim here is to confirm a result both in vivo and in vitro using the same method.
All skin types (type 1 - 4 with optional provenance) as well as hair types of Central European, Asian, Indian Caucasian as well as South American provenance are available as matrix.
The individual methods are shown below.
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De- and restructuring on hair - determination by dynamic differential calorimetry
The determination of the melting range of hair is a method that can be used in particular to record internal structural effects on hair. By determining the melting range of human hair, conclusions can be drawn about restructuring and destructuring caused by hair treatment agents. The method is offered both dry and in aqueous medium (HP-DSC).
Visualization of surfaces - confocal microscopy/surface light microscopy
Digital reflected light microscopy provides visualizations of the surface condition of the hair. Restructuring as well as destructuring of the cuticle can be visually illustrated.
This visualization is supplemented by confocal microscopy. By fusing the individual images, slice-by-slice focal images taken with this method provide a 3D representation, which is
- enable the precise measurement of the hair as real mathematical information regarding the thickness of the hair as a whole as well as measurements of surface effects (roughness determination).
- enable the 3D printing of a hair sculpture, which bring the effects on the surface close enough to touch.
Washing resistance of hair dyes
Both standard strands and removed subject hair are available as matrix for wash fastness determinations. The method used is a standard ultrasonic hair wash. LAB determinations are made both in vivo and in vitro and further supplemented by standardized subject photography for further visualization. This allows a statement to be made about the wash fastness of hair colorants as a function of time.
UV resistance of hair dyes
Both standard strands and subject hair (1/2-sided) are available as matrix for lightfastness determinations. After standard irradiation, both in vivo and in vitro LAB determinations are made and further supplemented by standardized subject photography for further visualization. Thus, a statement on the lightfastness of hair colorants as a function of time can be made.
Classification of color precipitates in the color space
After standard applications of hair colorants, LAB measurements are used to classify the color precipitates in the color space. The data obtained can be used for QM processes as well as for the creation of color boards. The data pool can be created both in vitro and in vivo.
Color chart
Fat content determination on skin and human hair
The fat content on hair and skin can be determined on a photometric basis. This allows statements to be made in vivo as well as in vitro about the regreasing of skin and hair depending on the use of certain treatment agents ad hoc or as a function of time. In this process, a special film is first applied to the skin/hair over a defined period of time. The lipophilic coating of the film wears off differently depending on the sebum quantity and does not react to moisture. This allows statements to be made about the grease content and the regreasing of the hair at the roots, lengths and tips directly after the application of treatment agents and as a function of time. Analogous determinations can also be made on the scalp. The induced value indicates a calculated amount of fat in g/cm2.
Sebumetry
pH determination on human hair
An in vivo and in vitro measuring electrode allows occlusion-free pH determination on skin and hair. The measurement can be taken directly on the test person, for example after coloration or reshaping, in a pH measuring range between 0 - 11.
pH-Metry
Gloss measurements on skin and hair
The glossymeter, which can be used in vitro as well as in vivo, is methodologically based on both directly reflected light and diffusely reflected light. A non-planar matrix (such as the hair) can thus undergo a reflection measurement in vivo. This reflection measurement on the subject in the test salon can complement the sensory perception of the parameter gloss as a direct measurement. The reflection is recorded as a gloss unit (GU unit: 100 GU = full reflection; 0 GU = no reflection).
Glossymeter
Moisture balance - determination by conductometry
Moisture balance of skin and hair is a term frequently used in cosmetics, but often without a tangible definition. The bpc laboratories competence center pays special attention to this hair and skin parameter and makes it ascertainable: validated by thermogravimetry, Karl Fischer titration and tewametry, a Moisture Index (MI) can be determined using a special conductometric method, which as a concrete value reflects a statement about a better or worse moisture balance of a sample compared to a reference.
In vivo measurement
Conductometry measurement results
Moisture balance - determination of evaporation rates on human hair
A special Tewameter probe can be used to determine the evaporation rate of water on the hair and skin. Information can be obtained about the water content of the hair or the water loss due to environmental influences (e.g. blow-drying or straightening) as a function of hair treatment agents. With regard to the skin, a statement can be made about the water loss of the skin or applied creams/lotions. Thus, a statement can be made about the influence on the moisture balance of skin and hair. The induced value indicates the evaporation rate (R) in g/h/m*m.
Tewametry in vivo
Tewameter measurement
Moisture balance on hair - determination by thermogravimetry
Thermogravimetry, validated by Karl Fischer titration, can be used in particular to draw conclusions about water loss from hair, for example during blow-drying or straightening. In vitro, the method is an important supplement to in vivo methods (determination of moisture balance) in order to make statements about water-retaining effects on the hair.
The method is further used to complement the tewametry method as well as conductometry method to determine a moisture balance on the hair.
Gravimeter
Mass loss during gravimetry
Anti-dandruff effect
Based on a standardized test salon method, scalp scales are collected quantitatively. These are then recorded with a special, high-resolution camera and automatically measured according to nine differentiated scales. By applying anti-dandruff preparations, not only a quantitative but also a qualitative statement about dandruff formation can be made.
Scale applicator
Handling of the scale applicator
In vivo acoustic combing determination
One of the most subject-oriented parameters is combability as a sensory perception. In order to record this, objective in vitro testing with extensive metrological effort is possible on the one hand, or pure sensory perception by a salon tester on the other.
To close this diffusion gap between in vitro and in vivo methods, the bpc laboratories Competence Center holds a special method: In-vivo combing is monographically tapped by directional microphones under sensitive standard conditions. The acoustic signal (waveform) picked up over a standardized period of time is displayed as a spectogram using the algorithm of the fast Fourier transform. In this way, sounds can now be represented in a frequency-related manner. The method can be used in parallel with sensory assessment of combability in vivo and can sample a bandwidth of up to 18kHz. By means of an extended sequence analysis, a combing determination index (CDI) can be determined, which reflects a concrete statement about a better or worse combability of a sample compared to a reference as a unitless value.
Sonography in vivo
Sonography/measurement results
Determination of foam properties
A salon test assessment of shampoos, shower baths and shaving foam provides practical data on cleaning and conditioning properties as part of a subjective survey. As a supplementary observation, light microscopic analyses are used to record foam bounce behavior, foam stability, foam quality and foam structure. On the basis of the reflected light microscopic classification of the foam, a relation to the information obtained from sensory salon tests is obtained.
Foam bounce behavior in half-side comparison