AUGUST, 1955
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TECHNIQUE FOR PREPARING HAND-DRAWN LANTERN SLIDES ARTHUR W. PAIRHALL University of Washington, Seattle, Washington
seminars and colloquia it is frequently necessary to display graphs and other data by means of a slide projector. The preparation of such slides by photographing inked drawings is usually time-consuming and expensive, and for many purposes seems hardly worth while. There are available materials for making slides called typewriter slides, using transparent plastic sheets and carbon paper, but their use for hand-made drawings is usually unsatisfactory because the pressure required to produce a sufficiently dark line results in tearing of the overlaying carbon paper and frequently of the plastic sheet also. This note concerns a simple way of overcoming this difficulty, and slides may he readily prepared of a quality limited only by the artistry of the person drawing them. I t is generally not possible to make an inked line directly on a plastic film. The ink will not adhere uniformly to the surface, resulting in a very uneven F O R
line. This difficulty may be readily overcome if the surface of the plastic sheet is first swabbed with a1coho1 containing two per cent acetone. The surface is altered so that one may draw on it with India ink as readily as on paper. The effect persists long enough that one can usually complete a slide before the surface again takes on its nonretentive character. As well as ease of drawing, this method has other advantages. One may readily make an erasure by simply wiping away the ink with an alcohol-soaked swab. Furthermore, any color of ink may be used, so that one may emphasize particular features of a given set of data by means of different colored inks, which are readily visible on the projected image because of their transparency. The author has used this technique on a number of occasions using polystyrene film, and has found the results to he very satisfactory.
