the transmitance curve of the sample changed rapidly during the exposure as
illustrated in Fig. 6a. The not-hydrated sample did not undergo a
visible damaging when exposed to vis/IR irradiation, but when
exposed to full spectrum radiation it resulted not photo-stable
(Fig. 6b), with a maximum difference of transmittance absolute
value of 10% at 300 nm for 10 min of exposure. Therefore, also
Vitro-Skin should not be used for photo-stability measurements.
In Fig. 7 the curves of absorption for each substrate considered,
calculated as A = 1 R T where R and T are the total reflectance
and transmittance as in Fig. 3, are reported. It is interesting to
notice that both Vitro-Skin and Transpore absorb UV radiation
mainly in the spectral region in which they are photo-unstable.Each substrate has been tested with the application of seven
different sunscreen products. The total absorbances A(l) are
reported in Fig. 8.