On glass quartering and pressure flaking

over-the-range.jpg

Following the advice of Kim Akerman I bought a copy of the above book, as it details the process of quartering a bottle using hot wires. However my book was a later edition to Kim’s and the page numbers differed. Anyway, the section relevant to this enquiry is at the beginning of chapter eight, regardless of edition. Apparently a long wire was heated in a fire and when ‘red hot’ twisted around a bottle base. This resulted in the base dropping off. The same procedure was then applied to the neck resulting in a glass tube. Finally the red hot wire was used to quarter the tube resulting in four equal sized glass preforms. In a previous post I discussed my hard hammer technique. Obviously, if this hot wire method is used no hard hammer work is necessary.

This section of the book also has useful details on the bodily approach to pressure flaking. An anvil stone is used and the knapper is seated with one leg tucked behind, and the other leg stretched out along the anvil. Some paperbark is placed upon the anvil to act as a cushion. The lengths of no.8 fencing wire used had both diamond and chisel tips, and these tips were regularly sharpened on the anvil stone. The wire was held “as we might hold a stick tight in the hand” (Idriess 1951: 47) with the fingers facing uppermost and the business end of the pressure flaker facing into the body. Leverage was generated by the “thumb and palm and arm” (ibid).

pressure flaking position

The glass would be held flat on the cushioned anvil stone whilst the pressure flaker was placed “firmly against one-half the width of the edge” (ibid). This would seem to be an important detail in that the edge is at approximately 90 degrees, as opposed to bevelled. This 90 degree approach allows flaking to be applied to each face equally. I need to play with this in order to understand it better. The knapper then “levered downward with a quick, short thrust, and a long, deep flake of glass flew out” (ibid). The longer flakes came from the convex (dorsal) face, whilst smaller removals were taken from the concave (ventral) face. Each edge was worked in turn. Through this process the piece was first flattened and then shaped and then finished. There is plenty to play with here and it has stimulated some thoughts upon ‘pulling’ as opposed to ‘pushing’ flakes off, and also on the relevance of ‘impulse’ versus slow and steady pressure. Ion Idriess has given me some ideas to test out.

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