1960 年 29 巻 11 号 p. 789-795
In the usual luster mensuration, luster is being measured without differentiating its quality and quantity. The writer discriminates the one from the other as
Quality of luster: the characteristic based upon the distribution of reflection from parts of surface which are very small to the extent that the resolving power of the eye comes into question.
Quantity of luster: the macroscopic characteristic based upon the average reflection from a reasonably large area of the surface which is regarded as uniform in luster.
On this basis, an automatic recording micro-luster meter has been devised to measure the quality of luster and an analytical formula is derived for the recorded curve to evaluate quality L as
where h: mean height of peaks,
l: mean height of valley bottoms,
D: distance between specimen and observer,
p: mean distance between adjoining peaks,
θ: visual angle subtended by peak and adjoining peak.
The above formula gives for example the value of L of silk (3.18×102) larger than that of cotton (1.40×102).
The value L needs to be within the range of 200_??_104 for the luster to be of good quality; if otherwise, surface pattern of the specimen, say a texture, either shows up too conspicuous or becomes indistinct by overall gloss.