correlations with R-squared values greater than 0.94 were found for all three instruments,
with R-squared values above 0.99 for the Skicon © 200. The data indicate a linear
relationship between skin hydration and glycerin concentration in the short-term test.
A positive correlation between glycerin concentration and improvement in expert visual
skin dryness/scaling grades has been reported for dry skin in both the pig model and in
human testing with repeated application over four weeks (16).
EFFECT OF SALT
The effect of NaC1 on the measurement of skin hydration by the three devices was
studied under different levels of glycerin. The salt effect was evaluated by using changes
of the measurements from baseline. The data are summarized in Table III.
We have found that NaC1 provided significant contribution (p < 0.05) to the readings
for all three instruments. When glycerin was not included in the formulations, salt
demonstrated small but significant negative effects on all three instrumental readings.
With glycerin in the formulations, relationships between instrumental readings and
NaC1 concentration were not linear. NaC1 increased the readings in the presence of
glycerin, with the maximum effect at 1.5% NaCl and with a lesser effect at 3.0% NaC1.
At 5% glycerin, 3% NaC1 did not have a statistically significant effect on any of the
instrumental readings, and at 10% glycerin, 3% NaC1 did not have a significant effect