< BLENDING WAXES
ADDING A COLOUR TO WAX
A colouring agent is also usually added into wax during the initial blending process. Most factory blends sold through art material’s suppliers will be pre-coloured, in contrast, bulk supplied refinery products are usually of an indistinct colour, presenting a somewhat translucent surface that makes it difficult to spot subtle faults in a wax pattern, or even visualise the eventual surface form of the cast reproduction.
The addition of a colour to a blend enables those working a wax model to SIGHT it’s surfaces and examine detail both clearly and accurately. The choice of colour for a casting wax is a matter of individual preference, though for practical and economic reasons most founders will often use just a single colour for all their waxes The majority of foundries show a marked preference towards greens of a mid to dark hue, as these tones approximate the natural oxide tendency of copper alloys. Black, blue, red and other wax colour variations are also commonplace.
Historically, a colour would be imparted to wax by the addition of a metallic salt – copper based salts for greens and blues, mercuric for reds, and lead for whites; though alternative colouring agents such as madder, indigo, saffron and turmeric were also sometimes used.
Exceptional skills in wax colouring technique were evolved in 17th century Europe, not for lost wax casting, but for the production of permanent wax models. Some of the best examples of this art are found in the polychromatic models of anatomical detail – ‘Le Cera Anatomiche’. Models include specimens produced for ‘La Specola’ (founded in Florence in 1675), as well as later examples created by eighteenth century master modellers, notably the Italian craftsman, Clemente Susini (1757-1814).
The use of coloured wax as a medium for executing finished sculpture and decorative work was popular as early as the 14th century, first in France, and later on in Italy during the 16th century, when wax was used to produce low relief portraiture of the aristocracy. The use of coloured wax as an sculptural medium in it’s own right continues to the present day, though by far the most common use of the wax in art and design work is as a transitional foundry material.
Waxes for foundry use today can be coloured with pigments, though more successful results are achieved through the use of aniline dyes, these impart a uniform, stable and relatively opaque colour to the wax. Specific hues or elaborate colour schemes can be achieved in wax through the addition of oil based paint pigmentation (the results not unlike the preparations created by ‘encaustic’ wax painters). For the most part though, a simple, uniform, mid tone colour is preferable in a foundry wax.
A BRIEF GUIDE TO WAX BLENDING >
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