Monday, September 1, 2014

ENGRAVING AND CHASING



Post 101   by Gautam Shah ➔
GLASS ENGRAVING on Windows of St Nicholas Church, Moreton, Dorset.

ENGRAVING

Engraving is the practice of incising a design or pattern onto a hard, usually flat surface, traditionally of copper, by cutting grooves into it. Other materials for engraving include Gold, Silver, Ceramics, Nickel, Steel, Brass, Titanium, Wood Gems, Precious stones, Glass and Acrylics. Traditional engraving, by burin, graver (sharp pointed hardened steel hand tools) or with the use of mechanical or pneumatic and laser machines by goldsmiths, glass engravers, gunsmiths, and others. It is used for producing images on paper, in artistic printmaking, in map-making, and utensils texturing. Modern professional engravers can engrave up to 40 lines per mm.

Engravers tools -Burins


Engravers tools

While engraving when pressure is applied with a hammer, the process is called carving. The tools have not only use hardened carbide tips but also diamond bits. The feed (the depth the tool is allowed to incise), the speed (slow, fast) the movement (vibratory, non-circular etc.), are all often predefined and controlled. Identical patterns are incised by using masters or by controlling the feed through a pantograph. Pantographs are also used to enlarge, reduce the scale, directionally stretch or even reverse orientation of the pattern. Automatic mechanical engraving tools can do as fine a work like a gramophone record or lasers can engrave a CD.

 
Engraving work piece Holder

Pantograph used for enlarging and reducing details


 Computer controlled engraving


Laser Engraving


Linocut engraving



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CHASING

Engraving is done by removing a narrow fillet of metal with a cutting or graving tool, whereas Chasing is made by depressing the surface with a blunt point and hammering along the line to be delineated, but without removing any material.

Both of these techniques are widely used for precious metals. Chasing is accomplished with a hammer and punches on the face of the metal. These punches are so shaped that they are capable of producing any effect, either in intaglio, incising beneath the surface of the metal, or in relief. The design is traced on the surface, and the relief may be obtained by beating down the adjacent areas to form the background.

Such chased relief work sometimes simulates embossed work, but in the latter process the design is bossed up from the back. The detailed finish of embossed work is accomplished by chasing.

The term chasing is also used to describe the touching up and finishing of cast work with hand-held punches. Engraving involves cutting or incise a line, broken line, dot or point on a surface of metal. Engraving is always done with a cutting tool, generally by pressure from the hand. It detaches material in cutting.
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ETCHING

Engraving and Etchings are processes that offer closer results. Etching is done by removing a material by acid or mordant the unprotected parts of a metal surface to create a design in intaglio. Etching is used to create patterns and designs over glass, plastics, metals, stones and marine products like conch, sea and egg shells.

Sea shell etched

Egg Shell etched

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REPOUSSE or REPOUSSAGE  

Repousse or Repoussage is a process to form patterns or images in low relief, on a malleable sheet metal surface by hammering from the back side. Chasing is the opposite technique to Repousse. Repousse is used from the other face of the metal to form a raised design on the front, whereas chasing is used to refine the design on the front of the work by sinking the metal. Both the processes are used, to a form a design. It is also known as embossing. There is no loss of metal in the process, as it is stretched locally and the surface remains continuous.


Etruscan Mirror

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