Sunscreen Tester

The following characteristic values
are measured or calculated:

SPF

sun protection factor

PFA

protection factor in UVA, divided in UVA1 and UVA2

t

spectral transmittance

a

spectral absorptance

c

critical wavelength acc.to Diffey

UVA/B

ratio of UVA protection effect to UVB protection effect

Information about the time-dependent stability
of a suncare product is automatically obtainable.

State of Technology

With all in vitro methods used at present, the spectral transmittance of suncare products is measured in a spectral photometer. From the spectral transmittance, characteristic values for the protective effect in UVB and UVA are derived. The protective effect of a sun care product regarding the erythema is described by the SPF (Sun Protection Factor).

Measuring method and device

The sample is exposed to simulated solar radiation. The radiation source is a Xe-lamp, whose radiation is filtered by two selectively reflecting mirrors and different filters such that the spectral distribution in the wave-length range 290 nm < l < 400 nm corres-ponds to the standard sun of COLIPA and DIN 67501.

Behind the sample there are two radiation receivers which are used alternatively for UVA and UVB and are automatically driven into the path of the rays.

Spectral radiation receiver
(UV spectral radiometer)

With this radiation receiver the spectral irradiance E_? is measured with and without sample and the PFA (Protection Factor in UVA) is determined. It shows by which factor the irradiance in UVA is decreased when using the suncare product. Analogous to the average SPF, an average PFA is calculated as well as the spectral transmittance E_? and the spectral absorptance a _? =(1-t_?).

For a number of commercial suncare products with sun protection factors between 4 and 30, the SPF was determined by both the in vivo method and the new in vitro method. Both SPFs correspond to each other within an acceptable tolerance range.