GLASS PAPER. - In making this useful article, the fragments of broken wine bottles are carefully washed to remove all dirt, the glass is then crushed under a runner, and sifted into about six sizes as in manufacturing emery. The paper is brushed over with thin glue, and the pulverized glass is then dusted over it from a sieve, which completes the process. Sometimes two coats of glue and glass are applied, or Venetian red is mixed with the glue to give that tint to the glass and sand papers, and under Edward's Patent, thin cotton cloth is used instead of paper, as the vehicle for the glass.
See Flint, an article recommended instead of glass for the above and other purposes.
GLAZERS, or Glazing Wheels. - Wooden wheels covered with leather when charged with fine emery receive the above names, but when supplied with crocus and used for finer purposes they are called polishers. Such wheels charged with emery cake, bouldered and waxed to deaden the emery are much used at Sheffield. See Wheels, articles 50 and 51.
GUM LAC. - See Lac; also Corundum.
GYPSUM. - See Alabaster.
HACKING, a process employed in dressing rough grindstones, by notching or checkering the high parts with a hack hammer, which resembles a small adze of from one to three pounds weight, fitted with a short handle. The process is fully described under Wheels, article 15. 2. - The periphery or face of soft metal laps and wooden glaze wheels, are also in some cases hacked by the cutlers, with a very light sharp hammer, the edge of which should be as keen as a chisel, and used very delicately; but by far the more usual course is to score the edges of the wheels while they are at rest, with a pointed knife, which injures these tools less and entirely avoids the risk of spoiling the edge or angle of the lap, which should be scrupulously preserved. 3. - Lapidaries employ an entirely different mode of hacking or jarring their leaden pewter and copper polishing wheels, which are used with rottenstone and water, as fully described under the head Carnelian.
HARDWOOD. - See Wood.
HELIOTROPE. - See Bloodstone, and also the article on Carnelian.
HORN handles for razors, knives, and similar works when moulded (see vol. 1, page 125) are scraped and then buffed with Trent sand and oil, and afterwards with rottenstone and oil as more fully explained under the head "Tortoiseshell;" but upon which latter material the Trent sand is not used in its natural state, as it would be too coarse and vigorous in its action on that soft and expensive substance; for buffing tortoiseshell therefore the Trent sand is first calcined and pounded, and then passed through a muslin sieve. See article Tortoiseshell.
Horn is sometimes used by watchmakers as a vehicle for the application of polishing powders to flat works. See Machinery, article 13.