SKIN CARE
Experimental design Formulation Table 1 shows the formulation used for this study containing 20 wt.% biobased propanediol. The other two high moisturising formulations tested were identical to the biobased propanediol formulation above except for the humectant component as previously mentioned. The test formulations were manufactured and supplied by ACT Solutions Corp., Newark, Delaware, US.
Corneometer assessments of skin hydration Washout Phase: Subjects were provided with a bland soap product to use on their lower legs for days 1, 2 and 3 prior to the active phase. They were instructed not to use any other treatment products on their lower legs for the duration of the study. These products include moisturising foam baths, shower gels or soaps, lotions and creams, and depilatory products. Pre-treatment: On day 4, subjects were
instructed to not wash their lower legs for three hours prior to returning to the test centre. Upon arrival at the test center, subjects rested for a period of at least 30 minutes in a controlled environment at a temperature of 72˚F + 4˚F and at a relative humidity of 45% + 5%. Following the rest period the lower legs were marked with a total of five 5 cm x 5 cm squares using a gentian violet skin marker pen. Prior to application of the test formulations, three baseline readings were made at each site using the Corneometer CM825 (Courage and Khazaka, Germany). Active Phase: The subjects remained in
the controlled temperature and humidity environment for the 1 hour and 4 hour assessments. A single application of each
Table 2: Mean corneometer measurements. Test formulation
High moisturising Zemea High moisturising Glycerin
High moisturising Zemea/Glycerin Glycerin (Positive control)
Untreated site (Negative control)
Spreads easily
6.5 Absorbs easily 6.0 Smooth feeling
n Zemea n Glycerin n Zemea/glycerin mix
5.5 No filming 5.0 4.5 Feels comfortable
No greasy feeling
No tackiness
Soft feeling Feels moisturised Figure 2: Mean consumer sensory ratings.
of the test formulations was applied to each subject’s lower leg. One site remained untreated (negative control) and another site was dosed with 100% glycerin (positive control). The test formulations and control were applied randomly among the subjects. Corneometer assessments of skin hydration were conducted at 1 hour, 4 hours, and 24 hours following application of the test formulations. Prior to the 24 hour Corneometer assessment, subjects again
Baseline 18.0
17.0 16.1 16.9 17.7
Mean Corneometer measurements 1 hour 29.7
4 hours 28.7
35.8 34.3 95.7 17.6
34.6 33.1 85.3 22.1
rested for a period of at least 30 minutes in a controlled temperature and humidity environment.
24 hours 20.5
25.0 23.1 75.4 19.1
Table 3: Treated areas compared to baseline (p-values <0.05; 95% confidence level). Test formulation
High moisturising Zemea High moisturising Glycerin
High moisturising Zemea/Glycerin Glycerin (Positive control)
Untreated site (Negative control)
Baseline 0.7729
0.5854 0.1052 0.5242 N/A
74 PERSONAL CARE September 2015
Between-treatment comparison 1 hour
<0.0001 <0.0001 <0.0001 <0.0001 N/A
4 hours 0.0002
<0.0001 <0.0001 <0.0001 N/A
24 hours 0.2795
0.0008 0.0069
<0.0001 N/A
Consumer sensory perception This was a blind, randomised test with a three-day product use cycle. Subjects visited the test centre on day 1 of the study and three 3 cm x 3 cm squares were marked on the subjects’ volar forearms in indelible skin marker. A qualified technician then made a single application of each of the test formulations to the marked areas. The subjects returned to the test centre on days 2 and 3 for additional applications of each of the test formulations to the marked areas. On day 3 of the study, immediately following each product’s final application, the subjects completed questionnaires to report their level of agreement on a scale of 1 to 7 with 10 different statements regarding each test formulation’s sensory and use characteristics.
Results Corneometer assessments of skin hydration The mean Corneometer measurements for moisturisation are presented in Table 2 and Figure 1. Baseline measurements demonstrated that there were no statistically significant differences between
Pleasant experience
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