Hair Color Vibrance Factor to Characterize Shine and Color Intensity*

Jan 1, 2012 | Contact Author | By: Timothy Gao, PhD; Peter Landa; Regan Tillou; and Kevin Gallagher, Croda Inc.
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Title: Hair Color Vibrance Factor to Characterize Shine and Color Intensity*
hair color vibrance factorx color intensityx hair shinex chromax overlapping coefficientx
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Keywords: hair color vibrance factor | color intensity | hair shine | chroma | overlapping coefficient

Abstract: To evaluate the comprehensive effects of shine and color intensity in hair, a hair color vibrance factor has been developed to enable new claims for hair dye formulas and after-dye treatments. Experimental results described here show how varying the ingredients in shine spray and hair dye formulas affect this factor and correlate with subjective panelist assessments.

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* A portion of this paper was presented in December 2010 at the annual New York meeting of the Society of Cosmetic Chemists.

Luster or shine is an important feature of hair’s appearance and this visual effect is a key objective in the consumer hair care market. Color strength is another important attribute for colored hair but no parameter or test method has previously been developed to combine the two and enable quantified vibrancy claims. In relation, based on work by Lefaudeux et al., in the present article, the authors define a new parameter for such claims, the hair color vibrance factor (HCVF).

Technical Background

Lefaudeux et al. published on principles for measuring hair luster (shine) using a device designed to measure scattering sources on a hair tressa.1, 2 As shown in Figure 1, the researchers indicated two bands that were captured in images of colored hair: the shine band or first reflection with no color; and the chroma band or second reflection with color. From these observations, the researchers defined an overlapping coefficient to describe the overlapping degrees between shine and chroma (see Figure 2). It was also observed that after hair was treated with certain cosmetics, this coefficient increased and corresponded with shinier, richer color.

Considering this work and the established interaction mechanism between hair fibers and light,1 the authors defined the HCVF by measuring the comprehensive effects of hair shine and hair color strength (chroma) as shown in Equation 1:

HCVF = L (1 + Oc) = L + L* Oc Eq. 1

where L is the shine index as determined by: the light scattering measurement device previously mentioneda, and by using the BNT equation shown in Equation 2 below; and Oc is the determined overlapping coefficient between hair shine and chroma.

In Equation 2, Sin is the integral inside the specular peak in the specular profile, Sout is the integral in the wings of the peak in the specular profile, D is the integral in the diffused profile, and Wvisual is the mean value of the band width along the region of interest (ROI) from the real image.

A previous study3 by the authors established the experimental procedures and parameters to quantitatively determine hair shine using a Hair Visual Appearance Study System. In addition, the study applied the HCVF to evaluate colored hair. In the present study, the authors use this system to evaluate the effects of a hair spray using the HCVF.

Materials and Methods

Virgin dark brown, Oriental black, blond and natural white hair tresses, as well as regular bleached shades were purchasedb. Commercial auburnc and deep red hair dyesd were used to dye a portion of the white hair tresses. Hair shine spraye consisting either of 55% cyclomethicone and 45% PPG-3 benzyl ether ethylhexanoatef or 55% cyclomethicone and 45% PPG-3 benzyl ether ethylhexanoate were used to treat some of the tresses while others remained untreated, for comparison.

For the shine spray tests, hair spray bottles were held 5–6 in away from the hair and sprayed lightly in sweeping motions three times on each side. Three tresses were treated by the same hair spray and combed to distribute the product evenly throughout. The treated hair tresses were then left at room temperature (23°C) overnight for drying. The scattering of light on hair was measureda from two orientations, i.e., root-to-tip and tip-to-root, to determine hair luster (LBNT), chroma (C) and the overlapping coefficient (Oc) of each tress.

Effects of Hair Color Shade

First, untreated clean natural white, blond, dark brown, black, bleached, dyed auburn and dyed deep red hair tresses were evaluated. The typical light spectrums for the untreated samples of different colors are shown in Figure 3a, b, c and d. The determined values of shine index (L), overlapping coefficients (Oc) and calculated HCVF are listed in Table 1. It was observed that hair shine value of untreated hair increased with hair color darkness. This may be attributed to more light being absorbed and less light being scattered in dark-colored hair, whereas in light-colored hair, more light is scattered and less light is reflected.

Dyed auburn and red-colored hair showed relatively less shine and smaller overlapping values compared with natural brown and black hair, which is due to damage caused by the coloring process. White hair provided the most unique results; it possessed the lowest shine value but the highest overlapping coefficient. This can be attributed to high amounts of scattered light at all wavelengths and broad bands of both shine and chroma, even though the chroma value was low.

Effects of Shine Spray

A hair shine spraye was then applied to the tresses. The percent changes in hair shine index, overlapping coefficients and HCVF values before and after treatment are shown in Table 2, and typical images and light spectrums of auburn-colored and deep red-colored hair tresses are shown in Figure 4a, b, c and d. In general, it was observed that the shine spray greatly improved shine on blond and bleached hair and moderately enhanced shine for white and dyed hair but had less of an effect on black hair. The spray also showed great improvement in the shine/chroma overlapping coefficient of dyed auburn and deep red hair and made it more vibrant.

Subjective Evaluation

To test the effects of different shine spray ingredients on HCVF, three auburn-dyed hair samples including a control (Sample A) and two samples treated either with hair spray B (Sample B)—including 55% cyclomethi-cone and 45% phenyl trimethicone, or treatment Ce (Sample C) were subjectively evaluated by 25 panelists chosen at random. Figure 5 shows images of the samples. All panelists visually inspected hair tresses and answered the following five questions: Which tress has the most shine? Which tress has the most vibrant color? Which tress has the strongest color? Which tress has the brightest color? And in general, which tress has the most striking color?

Figures 6 and 7 represent the determined HCVF values and panelists’ preferences (%) for the hair samples, respectively. The auburn-colored hair samples treated with spray C were rated as having more vibrant color and had a higher HCVF value than the control A or Spray B samples. Results from subjective evaluations were therefore in agreement with those obtained from instrumental measurements—the higher the HCVF value of the sample, the more vibrant and brighter in color it appeared.

Effects of Hair Dyes: Natural vs. Vibrant Black

To test the effects of different hair dye ingredients on HCVF, two black hair dye formulas were prepared (see Table 3). Figures 8a and b shows images of two black color-dyed hair samples taken by the aforementioned devicea and a regular digital camera. HCVF values of these dyed hair samples are listed in Table 4. It can be seen that the vibrant black hair showed darker, shinier and more vibrant color, compared with natural black hair. In addition, the vibrant black hair had lower L* value (i.e., more darkness) and more negative b* value (i.e., bluer color).

Conclusion

HCVF has been established in this article as a parameter to characterize the comprehensive effects of hair shine and color intensity (chroma) by measuring the hair shine index, chroma maximum and overlapping coefficient simultaneously. Subjective evaluations showed good agreement with objective measurements. HCVF is therefore suggested as a means to quantify new claims such as vibrant color or vibrancy-enhancing hair treatments—the higher the HCVF value, the more vibrant the hair color looks.

The authors thank the Croda Application Group for its preparation of tested formulations, and Rob Comber, PhD, and Abel Pereira for their support and help.

References

  1. N Lefaudeux, N Lechocinski, O Clemenceau and S Breugnot, New luster formula for the characterization of hair tresses using polarization imaging, J Cosm Sci 60(2) 153–169 (2009)
  2. SAMBA Hair System Manual, Bossa Nova Technologies, available at www.bossanovatech.com (2008)
  3. T Gao, A Pereira and S Zhu, Study of hair shine and hair surface smoothness, J Cosm Sc 60(2), 187–197 (2009)

This content is adapted from an article in GCI Magazine. The original version can be found here.

 

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Table 1. Value of L, Oc and HCVF of different colored hair samples

Table 1. Value of L, Oc and HCVF of different colored hair samples

  White Blond Bleached Brown Black Auburn Deep Red
 1.69  8.45  6.46  31.5  34.6  7.68  13.4
Oc  99.00  80.80  86.10  77.8  89.5  70.90  60.2
 HCVF  3.36 15.30  12.00  52.9  65.6  13.10  21.5

 

 

Table 2. Changes in L, Oc and HCVF of different hair color shades after spraying

Table 2. Changes in L, Oc and HCVF of different hair color shades after spraying

   White  Blond  Bleached Black  Auburn  Deep Red 
ΔL (%)   45.0  98.80  157  3.47  70.6  45.5
 ΔOc (%)  0.1  4.58  0  4.47  23.3  24.8
 ΔHCVF (%)  44.9  103.00  157  5.65  87.0  59.1

 

 

Table 3. Formulas for vibrant dark and natural black dye

Table 3. Formulas for vibrant dark and natural black dye

 Ingredient  Vibrant Black  Natural Black
 Water (aqua)  25.2% w/w  26.89% w/w
 Sodium Sulfite  0.4  0.4
 EDTA  0.07  0.07
 L-Ascorbic Acid  0.4  0.4
 Toluene-2,5-Diamine Sulfate  3.17  2.2
 Resorcinol  0.72  0.58
 m-Aminophenol  0.64  0.44
 2,4-diaminophenoxyethanol Sulfate  0.58  0.2
 Isopropyl Alcohol  18.0  18.0
 Sorbitan Isostearate  5.0  5.0
 Cocamidopropyl Hydroxysultaine  5.0  5.0
 Acetamide MEA (Incromectant AMEA-100, Croda)  1.02  1.02
 Cocoamidopropyl Betaine  5.0  5.0
 Oleyl Alcohol  10.0  10.0
 Oleic Acid  6.0  6.0
 Oleth-5 Phosphate (and) Dioleyl Phosphate  4.0  4.0
 PPG-5-Ceteth-20  2.0  2.0
 PEG-3 Dioleoylamidoethylmonium Methosulfate  1.8  1.8
 Hydrolyzed Wheat Protein (and) Hydrolyzed Wheat Starch  0.5  0.5
 Wheat Amino Acids  0.5  0.5
 Ammonia, 28%  10.0  10.0
   100.0  100.0

 

Table 4. HCVF values of natural black and vibrant black hair

Table 4. HCVF values of natural black and vibrant black hair

Hair Dye Formula HCVF Oc (%) Shine (L) L* b*
Natural Black 50.6 97.5 25.6 20.1 -0.60
Vibrant Black 54.6 98.6 27.5 18.5 -2.19

* L and b* were determined by the XE Spectrocolorimeter, manufactured by LabScan Analytical Science, Gliwice, Poland.

Figure 1. Interactions between light and a human hair fiber2

Figure 1. Interactions between light and a human hair fiber2

Figure 2. Complete decomposition of light into shine, chroma and diffusion

Figure 2. Complete decomposition of light into shine, chroma and diffusion

Figure 3a. Typical light spectrums of untreated black hair

Figure 3a. Typical light spectrums of untreated black hair

Figure 3b. Typical light spectrums of untreated brown hair

Figure 3b. Typical light spectrums of untreated brown hair

Figure 3c. Typical light spectrums of untreated red hair samples

Figure 3c. Typical light spectrums of untreated red hair samples

Figure 3d. Typical light spectrums of untreated blond hair sample

Figure 3d. Typical light spectrums of untreated blond hair sample

Figure 4a. Typical hair images and light spectrums of auburn-colored hair before treatment

Figure 4a. Typical hair images and light spectrums of auburn-colored hair before

Figure 4b. Typical hair images and light spectrums of auburn-colored hair after treatment

Figure 4b. Typical hair images and light spectrums of auburn-colored hair after treatment

Figure 4c. Typical hair images and light spectrums of deep red-colored hair before treatment

Figure 4c. Typical hair images and light spectrums of deep red-colored hair before treatment

Figure 4d. Typical hair images and light spectrums of deep red-colored hair after treatment

Figure 4d. Typical hair images and light spectrums of deep red-colored hair after treatment

Figure 5. Auburn-dyed hair samples, a) without treatment, b) treatment with Sample B and c) treatment with Sample C

Figure 5. Auburn-dyed hair samples, a) without treatment, b) treatment with Sample B and c) treatment with Sample C

Figure 6. HCVF values of hair samples

Figure 6. HCVF values of hair samples

Figure 7. Panelists’ preferences of hair samples

Figure 7. Panelists’ preferences of hair samples

Figure 8a. Images of natural black and vibrant black hair; hair images from the hair systema

Figure 8a. Images of natural black and vibrant black hair; hair images from the hair systema

c Superior Preference

c Superior Preference is a hair dye manufactured by L’Oréal USA, New York, USA.

a SAMBA Hair System

a SAMBA Hair System is a device manufactured by Bossa Nova Technologies, Venice, Calif., USA.

b Tresses were purchased...

b Tresses were purchased from International Hair Importers Inc., New York, USA.

d Clairol’s Herbal Essences Hair Color

d Clairol’s Herbal Essences Hair Color is a hair dye manufactured by Procter & Gamble, Cincinnati, USA.

e SC182 is a hair shine spray

e SC182 is a hair shine spray prepared by Croda Application Group, Edison, N.J., USA.

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