Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

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plastic welding

The process of sealing two or more layers of material by means of the introduction of a high frequency voltage field between two electrodes. The electrodes conduct the high frequency current through the material and also bring the surfaces in close contact, thus ensuring an efficient weld. When power is applied, the agitation of the molecules within the plastic causes a rapid rise in temperature until the softening point is reached, whereupon the plastic sheets fuse along the seam of the electrodes. Because the line of fusing must be outside the area of the document being sealed, it is necessary to cut the plastic sheets somewhat larger than the document. (276 )




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