Independent tests on McKee Fluidized Glazing  Cells by :- Prof. Dr. Heinrich Kaase at the Institute for Electronic and Lighttechnik the University of Berlin, Germany. And by the R&D dep. of Vegla Glaswerk, Aachen, Germany, under the direction of Frank Rubbert Dip. Eng. manager of R&D.

The tests were on  fluid cells with different concentrations of the active Dye in parts per. million  (ppm.)
The construction :- 6 mm. clear glass - /- 6 mm. fluid cell -/- 6 mm. clear glass. 
Antifreeze:- The Berlin samples had 23 % propylene glycol, the Vegla samples No antifreeze, the reason for the small differences. Both sets of samples had a similar biocide added.