120 Samples of roofing tile which may be regarded as representing the typical recent Japanese products were selected from about 1000 exhibits displayed at an exhibition by 29 centers of the industry.
The samples were subjected to the reflection test in visual region using a spectrophotometer, whose results were represented by the chromaticity diagrams by means of the 30 selected ordinate method of I. C. I. using the illmination C.
Investigations of the surface films of smoked tiles by X-ray have revealed that they contain pure graphite, which confirms the results obtained by other authors. Moreover, their silvery surface layer showed 19.5% of reflection and more than 21.8% of visual efficiency.
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