A Method for the Preparation James A. Rice, James F. Ranville, and Thomas Wildeman Colorado School of Mines, Golden. CO 80401
Recently two articles describing techniques for preparing high-quality presentation slides have appeared in THIS JOURNAL.^.^ Both procedures produce slides with a hlue background and transparent text from hlack lettering on a white background. A third method which produces a slide similar to that of the previously described methods is t o photograph the artwork with Kodak SO-279 film. Introducing color into the artwork in any of the above techniques, however. is either not nossihle or will oroduce results which are not &ways aesthetically appealling. This paper presents a rapid, uncomplicated, and inexpensive method for preparing high-quality, multicolored presentation slides utilizing a technique known as "color reversal".
Procedure The equipment and photographic supplies needed are given below 35 mm SLR earners
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copy stand fitted with 150-W tungsten or daylight-balanced light bulbs Ektachrome tungsten color slide film, ASA 160 blue filter (optional) gray card (optional)
These materials should he available a t any photographic supply store. Use of brand names in this paper does not represent an endorsement of a particular product. T o produce multicolored slides requires that color he incornorated into the desien of the orieinal artwork. Once completed, the artwork isWphotograph&on the copy stand usine the tunesten film with or without the hlue filter. We havefound tgat using the camera's internal meter to determine the exoosure from the artwork and then overexoosine theslide 1to 1.5 f-stopsproducesgoodresults. ~ l t e r n & i v e l i the camera's internal lieht meter mav he used to determine the exposure from a gray card and then the slide is overexposed 0.5 f-stops. Once exposed the film is developed by the C-41 process developed for Kodacolor color negative film instead of the Ektachrome E-6 process developed for color slides. This technique results in what is known as "color reversal". The C-41 development process should he available a t any photographic lab.
Results The colors which result are not those in the original artwork hut have been created through the reversal orocess. The table summariles the effects of Lversal on several ZipA-Tont: rolors (self-adherhe:acetate colorine sheets) ohotographed with ASA 160 ~ k t a i h r o m tungstencolor e slide film. Text prepared with hlack lettering on a white background
' Lyle, J. L. J. Chem. Educ. 1985, 62, 222.
Wright, N. A,; Blevins, D. B. J. Chem. Educ. 1984, 61, 800. Eastman Kodak Company "Encyclopedia of Practical Pholography." Amphoto: Garden Cily. 1978; Vol3. p 438. 608
Journal of Chemical Education
m e Effect of Color Reversal on Zlp-A-Tone Colors Normal Color blad white red orange
yellow green blue purple rhdamine red
Number 2720 2721 2545 2535 2504 2657 2605 2575 2565
Reversed Color
whiie black light blue medium blue dark blue pink orange light green
army green
will oroduce a slide with white letterine on a dark erav or black background, Omission of the h1u;filter will resuit in slides which exhibit a blue-erav backeround hut no sienificant difference in the reversal iolors. In the Ektachrome E-6 process the first developer produces a negative hlack and white image by reducing the exposed silver halides. The color developer used in the process' next step reacts with the remaining silver salts to produce a color positive image. The C-41 process produces a color negative directly from the exposed silver salts. By using C-41 processing on Ektachrome film a color slide is produced with reversal c01ors.~ The presence of a dark hackground presents a distinct visual contrast t o color that effectively emphasizes the desired information. The reversal to a hlack or dark-gray hackground from one orieinallv " white has been observed onlv kith Ektachrome tungsten film ASA 160. Other films (E
