Printmaking Techniques: Etching, Halftone, and Ceramics
Halftone Printing
Halftone printing involves gradually raising the gray and white tones to eliminate roughness, similar to drypoint. It limits the number of prints due to the press crushing the roughness.
Halftone Features
- Amplitude and smoothness of the black.
- A unique engraving system that allows real chiaroscuro.
- Halftone engravings are recognized by a characteristic densely crosslinked derivative of graphing, particularly visible along the edges.
Etching
Etching is an indirect metal plate engraving technique using a mordant. The recording instrument burns only a veneer superimposed on the plate. The true metal is cut through the chemical action of dilute acid, usually nitric acid, formerly called “etching.”
Care is crucial in the acid’s action. Insufficient etching results in faint lines, while excessive etching causes broad and jagged incisions, corroding the metal. During the process, the recorder can stop the acid’s action on some areas and reintroduce the plate, allowing for scratching the varnish rather than the metal itself, achieving the greatest hits in etching.
The mark of etching is pictorial, with soft and slightly irregular edges.
Etching reached its peak in the second half of the eighteenth century and gave way to lithography in the second decade of the nineteenth century. It regained importance after the mid-nineteenth-century decline of lithography.
Ceramics
The term “ceramics” derives from the Greek word ÊåñáìéêÞ, female of Êåñáìéêüò (ceramic) [ÊÝñáìïò = Clay]. Ceramics involve modeling elements with a mixture of clay and water, then firing them.
The manufacturing process, consistent since ancient times, includes:
- Preparation of clay or dough (mixing and kneading)
- Modeling
- Drying
- Weatherproofing
- Decoration
- Firing
Ceramic Waterproofing
Waterproofing prepares the object to contain liquids. Multiple steps are involved, depending on the object’s type and quality. Various techniques have been used since ancient times:
- Bruno: A primitive system where a pebble or instrument removes porosity from the object. Sometimes, a thin layer of clay is applied with a brush.
- Glazed (Coated): Characteristic of Eastern cultures, this involves covering the object with a glassy and transparent varnish. The varnish is a mixture of pure silica and lead oxide, crushed, pulverized, and dissolved in water. Some clays are vitreous compounds, reacting during baking to give the object a glassy sheen.
Glaze Colors
Color can be added to glazes using natural lands:
- Yellow and brown: Iron and antimony compounds
- Green: Copper
- Blue: Cobalt
- Purple and turquoise: Manganese
- White: Tin oxide
- Slip: A smooth, refined clay mixture mixed with water, providing a non-transparent layer on the ceramic object. Motifs are painted or attached with a layer of glaze before baking. Widely used in antiquity in the eastern Mediterranean and Mesopotamia. It spread in Europe at the end of the fourteenth century (mezzamayólica).
- Cover: White opaque varnishes obtained by adding tin oxide to polished lead. This coating allows full coverage of the clay base color and is used in…