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  • painshill
    started a topic Cones and Triangles etc

    Cones and Triangles etc

    DEBURRING STONES

    Deburring Stones (also known as deburring media) are modern items that may look and feel like stone, but are most usually made from ceramic. These days, they are often made of some high tech material to which abrasive compounds may have been added. Typically, they are relatively small – not more than one or two inches in size – in tan, brown, grey or black and can come in a variety of shapes, like this:


    [pic from Grav Company LLC]


    These items are used in large quantities in a tumbler (smaller ones may be pumped through an air or water-gun in the manner of a “shot-blaster”) to remove burrs from metal items which have been cast and/or subjected to machining operations such as hammering, grinding, drilling, engraving or lathe-turning. When modern small industrial items are cast and/or machined in steel, they often come out of the process with unwanted sharp edges (known as “burrs”) or metal that has seeped into the mould-join (known as “flash”). These unwanted defects are removed by the deburring process. Typical uses are for finishing screws, nuts, bolts, cogs and gears, as well as a wide variety of parts used in automobile construction.

    The shape of deburring media is designed to ensure that their abrasive action reaches the affected surfaces of machine parts which may have holes and intricate designs. The conical ones are normally rather smooth to begin with and can be mistaken for polished Native American “conestones”:


    [pic from the seller grumpydriver on ebay]


    The triangular items normally start out with crisp angular edges, but after use will also take on a smoothed appearance suggestive of having been worked – leading finders to believe that they are artefacts. Here’s some examples from forum members:


    [pic by Butch Wilson]



    [pic by Ray Martin]


    When deburring stones reach this kind of level of wear they begin to lose their effectiveness and can be found dumped all over the place – especially in the vicinity of industrial premises. They seem to find their way into creeks, rivers and fields even in rural areas.

    Although there are precedents for Native Americans in some areas producing “conestones” (with either ritual or gaming usage), they are normally a rather more shallow domed form which does not have the typical shape of deburring media and are normally made from more attractive stones including (notably) hematite. There is no particular precedent for Native Americans producing or using triangular stones – apart from much larger items (up to megalith size) believed to have been placed outside tipis, lodges, caves and burial areas to block the entry of uninvited spirits. Most usually those kinds of stones are naturally broken/weathered and chosen for their existing shape.
    Last edited by painshill; 01-28-2016, 09:20 AM.

  • painshill
    replied
    KILN SUPPORTS

    Kiln supports (also known as kiln spacers and kiln furniture) are items made from fired clay which were used to support and/or stack raw clay pieces being fired in a kiln and also sometimes to support multiple racks within a kiln so that it could be loaded with more items. They allowed free movement of hot air around the pieces during firing so that they fired evenly.

    Common pieces from the historic era (non-Native American) were cone-shaped. Here’s a couple of examples from the 18th Century or thereabouts which are typical of those used by European potters:


    [pics from UK Portable Antiquities Scheme database]


    They would usually either be arranged in groups of three to form a kind of tripod support, or in groups of four with one cone supporting each corner area of the item. Note that the bottoms are slightly convex so that the area of contact with the items being fired was minimised if several items were to be stacked on top of one another… a pile of dinner plates for example.

    As pottery glazing techniques improved and there was a desire to leave the glaze as free from imperfections as possible, the supports were produced with pointed tops and bottoms to further minimise the contact areas. Like these items, which date from the 1850’s:


    [pic from Timothy James Scarlett on the Utah Pottery Project Archaeology blog]


    Note that those above are trihedral pyramids, each one having three pointed “feet” and are usually known as “spurs” or sometimes “sagger spurs”. As glazing techniques advanced further still and highly decorated pieces were required to be blemish-free, all kinds of purpose-designed supports were used to accommodate pottery of different sizes and shapes. Some of these forms were generally known as stilts or saddles, like these:


    [pic from Fine Dictionary website]


    In addition to purpose made cones and such, old lumps of unwanted fired clay were used as shelf supports and spacers for less precious items such as stoneware crocks and jugs. Here’s some examples dating somewhere between 1850-1899 (note that these are glazed):


    [pic from AncientPoint website]

    NOTE: The cone-shaped items in that picture have a strong resemblance to items used as pottery “anvils” by both Native Americans and early settlers for hand-forming pots. The outside of a block of wet clay in which a cavity had been made would be beaten with a wooden paddle while holding the anvil inside the cavity to thin and shape the walls of the pot. Generally, these anvils have a much more convex bottom, bordering on hemispherical and the general shape may be more mushroom-like and less cone-like. Sometimes, the handle has a couple of “dents” in it to create a hand-grip. Native American items would never be glazed like that.
    Last edited by painshill; 01-28-2016, 09:22 AM.

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