Cesia and paints: An atlas of cesia with painted samples

CAIVANO, JOSE LUIS; MENGHI, INGRID; IADISERNIA, NICOLAS

AIC 2004 Color and Paints, Proceedings of the Interim Meeting of the International Color Association

International Color Association

Año: 2004; p. 113 - 116

The name “cesia” has been given to the modes of appearance produced by different spatial distributions of light. From the physical point of view, an object may absorb light, and the non-absorbed portion can be either reflected by the material, or transmitted trough it. Both reflection and transmission may occur regularly (specularly) or diffusely, and any intermediate combination may also appear. These are the stimuli for the visual sensations of cesia: transparency, translucency, glossy or mirror-like appearance, and matte appearance, with different degrees of lightness, and all the intermediate or combined cases. Every color appears in some of these modes of appearance. Now on, the stimulus for color can be produced by primary sources (objects that emit light) or by secondary sources (objects that reflect or transmit the light coming from another source). Both in a primary or a secondary source we can have a variation of color, but the variations of cesia only occur in secondary sources, that is to say, in objects that produce changes in the spatial distribution of light that they receive. These changes are mainly due to micro-textural variations on the surface or in the volume of the object. If these textural variations are of a rather small size, then the texture itself is not perceived, but the effect produced on light is, and we see cesias. Paints are one of the most versatile materials to produce these kinds of variations. A paint may cover a surface, working as an opaque coating, and in that case the stimulus for cesia is due to the surface finishing. A rough surface produces a matte effect, while a polished surface produces gloss. But if the paint is more or less transparent, then, in addition to the surface finishing, the internal composition, working in the whole thickness of the layer, is important. In these cases, the stimuli for cesia are of a more complex nature. An atlas of cesia made with pieces of glass was presented in AIC 1997, Kyoto. The aim of this paper is to present and explain a new atlas of cesia produced with painted samples. The atlas consists of 5 pages with 25 samples each, that is to say, a total of 125 samples. The samples in every page have a different degree of perceived permeability to light, from the opaque samples (1st page) to the transparent ones (5th page), passing through samples with different degree of perceived turbidity. Furthermore, in each page, the variation of lightness (from very light to very dark) and the variation of diffusivity (from matte or translucent to glossy or crystalline) occur. Figure 1 shows a scheme with the development of the first and last pages, and the indication of the three intermediate ones.