< PATINA FINISHING & PROTECTION
ENHANCED WAX FINISHES
Occasionally a dye or pigment may be added into a protective wax to enhance the colour of the patina. Pigmentation of a finishing wax is normally only done to obtain a very specific colouring on the cast’s surface – a colour that is difficult or impossible to achieve through the application of chemicals alone. In these circumstances, as near as possible a colour match attempted with a the chemcial patination, afterwards a more exact hue is obtained with the wax pigmentation. Some founders also add foreign material such as plaster or LUDO scrapings to the patina before waxing, this is sometimes referred to a FERRIC or CUPRIC & FLOOR, adding a light tonal variation to any undercuts across the cast’s surface.
A gratuitous application of coloured waxes and other pigmentation is generally avoided, mainly because assisted finishes of this type are considered relatively unstable in comparison to a full chemical patination. Care must be taken to ensure the chemical composition of any added pigmentation does not react adversely, either with the compounds present in the earlier deposited patina, or with the metals present within the underlying alloy of the cast (many pigments contain a significant metallic component). Likewise, some pigments are inherently unstable and will fade significantly upon long term exposure to ultra violet light or weathering. Despite these potential drawbacks, careful and considered use of wax pigmentation techniques can produce some very fine finishes. Not least an example of this is Edgar Degas’s ‘Petite Danseuse de Quatorze Ani’ (1880-81), a version of which can be seen in the Tate (Britain) Gallery, London. This particular work demonstrates Degas’s use of typically unorthodox techniques and materials. The underlying base patina on the ‘Dancer’ (probably a potassium sulphide based PENNY BRONZE), has been extensively modified and enhanced by (in this instance), an oil paint pigmentation carried in a beeswax body. This paint layer had also in part been worked over a paint primed surface (see PAINT) [ref].
ALTERNATIVE PROTECTIVE COATINGS >
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