Leonard Spialter and Jonathan S. Smith, II Air Force Reseorch Division wright-patterson AFB, Ohio
1;
Dye Solutions for the Preparation of Colored Slides
the course of preparing illustrative material for technical presentations, it was found that more striking, clearer, cheaper, and easier-to-prepare slides could be made by dyeing black and white transparencies than by taking color photographs of original colored illustrations. I n the latter method, not onlj must the original graphic material be prepared in color hut the resulting transparencies generally lack brilliancy. I n our approach we simply make negative transparencies, on film or glass, of the black and white illustration and then hand-tint the negative as desired. The resulting colors can he made quite brilliant. This technique can be used to differentiate individual curves on a complex graph or to identify fields or various portions of a slide for ease of referral during a lecture. Since the colors are applied by hand, this is one limitation to the application of the method. No closer resolution can be made between adjacent colored regions than that permitted by the width of the applying device. We have used fine brushes and even single fibers, however, to differentiate as many as five crossing curves, with each possessing its individual color. This happy possibility exists because we deal with negative transparencies where the opaque regions permit "slopping-over" of the colors. For the dye solutions we initially tried various waterbase colored inks but these proved generally to give poor results. They either did not wet the slides, gave a poor a m , or depended for their color on opaque pigments. The glass-marking inks were thick and difficult to apply, and proprietary dye solutions gave erratic results. In the long run it was found best to prepare our own solutions from commercially available dyes. Table 1 identifies the respective dyes, with the suitable solvent, color, and a quality rating (based on brilliance, uniformity of film, depth of color, and
general ease of application). In some cases a drop of aqueous Aerosol OT (Ameriran Cyanamid Corporation) was added per 5 ml of dye solution to facilitate slidewetting, but this proved generally unsatisfactory because of uncontrolled spreading on the slide. All of these dyes are standard biological stains and are available a t most laboratory supply houses, including Sargent, Matheson Coleman and Bell, Eastmdu Chemical, Fisher Scientific, Harleco, Mallinckrodt, and others. Dyes tried which proved less satisfactory as to solubility, color uniformity, or other signifirant properties include the following: Orange G, Congo Red, Alizarin Red S, Titan Yellow, Methylene Blue, Nigrosin, Alizarin Blue S, Methyl Orange, Methyl Green, p-dimethylaminobenzylidene Rhodanine, Quinalizarin, Phthalocyanine (metal-free) and Carmine. I n the use of the dyes recommended, practice is required to obtain a neat and nniformly colored slide but the results can be quite impressive. Table 1 Color
Uvr
Fluorescein (water soluble) Acridine red Methyl violet Anilide blue Erinehrome cyanin
R
Azure A Neutral red Aeriflavine (neutral) Quinoline vellow . & w i n e yellow CP.
&&I
red Nmhthol ereen B
Solution
Qmality
Yellow Lavender Deep blue Light blue Brown Blue Brown Yellow Light yellow Light yellow Brown Green
Solut,ions: 1, 500 mg dye dissolved in 5 ml anhydrous ethanol; 2, 500 mg dye dissolved in 5 ml ethanol-2 ml water. Quality: E, excellent; G , good.
Volume 38, Number 9, September 196 1
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