There is a dynamic relationship between the light effects represented in Impressionist paintings - and the natural luminousity of the materials and methods of handling used by the painters. Nineteenth century studio lighting was described by the English colour chemist George Field as 'subterraneous'. Henri Regnault was one of a number of contemporary colourists apart from the Impressionists who sought Mediterranean light and color adn introduced bright unbroken hues into his paintings. He was well aware of the darkening effects of studio-lighting and even went as far as saying: 'I flee from the abuse of black. It is our dirty Parisian studios with walls of grey, dark green or red brown whcih have corrupted our eyes and make us see insane shadows which inevitably invite exaggerated modelling.' Manet tried to improve the situation by having his models directly facing the light source. This 'full-face' light gave heightened luminosity and tonal contrast while minimizing half tones and shadows. Thus shadows in paintings like Olympia (1863) recede to the edges of the form, like strong contours and are extermely dark in contrast to uniformly pale tones on the nude flesh.
Many painters relied chiefly on daylght. Most studios's had high windows which let in the light. To supplement this light, artificial light in the form of candles or, more commonly oil lamps, amplified by shiny mental reflectors or reverberes. This by then old-fashioned lighting was specifically associated with clair-obscur effects - it was a soft, close lighting, yellow in color which produced focused highlight, a limited range of rapdly graduating midtones and deep, mysterious shadows. By this date, some painters were already lighting their studios from two or more windows -'secondary' light sources - and for more 'naturalistic' effects. Painters then graduated to using modern lighting tools such as gas, electricity. The use of gas street lamps in Paris grew from the 1820s and tranferred public spaces into venues of glittering palaces. Gas lighting in cafes and bars was augmented by reflections from large expanses of polished glass mirror. The construction of the Crystal Palace for the 1851 Great Exhibition used nearly a million square feet of glass and was perhaps Britain's most radical building of the nineteenth century. It's design was derived from the botanical greenhouse. It became emblematic not merely of a new potential for using natural light to create flooding interior illumination, but introduced the idea that interior daylight was very important. Artists modified their studios to accomodate this philosophy and very soon, Renoir's at Cagnes and Monet's at Giverny among others came increasingly close to resemble glasshouses.
The connotations of modernity versus nostalgia and similarly of light and dark moral sides to the city of Paris became epitomised in a comparison of Renoir's colourful light-filled The Pont des Arts( 1867) with the harshly etched monochrome of The Morgue ( 1854) by Charles Meryon. Artists often improvised by covering the windows in their studios with muslin cloth to achieve the desired balance of light and shadow. However some artists like Delacroix and Bazille were conscious of the monotony and false effects of light and shade in the academic studio. In 1854, Delacroix observed, 'Flesh reveals its true colour only in the open air and above all in sunlight....' Palliot agreed with him, 'Reflections, the reverberations, so delicate,so numerous, so varied outdoors, are in no way reproduced in a sombre and greenish site, illuminated by a single window which is often too narrow...'