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The introduction of hide glue
  • 2016-12-05 17:02:43
  • admin

     Hide glue is used in woodworking. It may be supplied as granules, flakes, or flat sheets, which have an indefinite shelf life if kept dry. It is dissolved in water, heated and applied warm, typically around 60°C (140°F). Warmer temperatures quickly destroy the strength of hide glue. Commercial glue pots, simple water baths or double boilers may be used to keep the glue hot while in use. As hide glue cools, it gels quickly. At room temperature, prepared hide glue has the consistency of stiff gelatin, which is in fact a similar composition.


     Gelled hide glue does not have significant strength, so it is vital to apply the glue, fit the pieces, and hold them steady before the glue temperature drops much below 50°C (120°F). All glues have an open time, the amount of time the glue remains liquid and workable. Joining parts after the open time is expired results in a weak bond. Hide glue's open time is usually a minute or less. In practice, this often means having to heat the pieces to be glued, and gluing in a very warm room, though these steps can be dispensed with if the glue and clamp operation can be carried out quickly.

 

    Where hide glue is in occasional use, excess glue may be held in a freezer, to prevent spoilage from the growth of microorganisms. Hide glue has some gap filling properties, although modern gap-filling adhesives such as epoxy resin are better in this regard.

 

    Hide glue that is liquid at room temperature is also possible through the addition of urea. An example of this type of mixture is Old Brown Glue,created by W. Patrick Edwards, the director of the American School of French Marquetry. In stress tests performed by Mark Schofield of Fine Woodworking Magazine, liquid hide glue compared favourably to hot hide glue in average strength of bond. "However, any liquid hide glue over six months old can be suspect because the urea eventually hydrolyzes the protein structure of the glue and weakens it – even though the product was 'protected' with various bactericides and fungicides during manufacture."

Related Readings: animal glue     gelatine animal glue


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