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Abstract
Relationships between covering power, CP, and particle size are presented for deposits of spherical, tabular and filamentary particles produced by physical development. Theoretical data are given for deposits of spherical particles and experimental data for such deposits produced with and without a blue-black toner added to the developer. CP is determined for specular and diffuse density measurement in light of various colours. Data areanalysed with the aid of an expression based on the Nutting density formula and, where possible, compared with theoretical expectations. The various factors which affect the colour of deposits are discussed with particular reference to the mechanisms of tone modification.
In general, with increasing particle size CP increases to a maximum for particles with projective areas in the region of 0.003 um2 and then decreases. The rate of increase of CP, its maximum value and optimum particle size for maximum CP depend on particle shape and the degree of tone modification.
Notes
Part I. Farnell. G.C. and Solman. L. R., J.Phot. Sci 18, 94 (1970).
Paper presented at a symposium on “Faclor Limiting Photographic Performance” oraonized by The Royal Pholoaraphic Society on 11-13 December 1968 In London.