Black and White Positive Slides In an article in this Journal Brooks et al.' stated that they had started to use the technique of solarization to produce black and white slides because earlier use of color films had not allowed them to achieve reasonable results with a minimum of difficulty. This article has led us to believe that i t is not widely appreciated that positive black and white slides can be obtained from essentially any black and white film. In fact, we have found two very good films of very high quality and ultra-high resolution whieh are available in small enough quantities that even small chemistry departments can inexpensively make their awn black and white positive slides. In the following paragraphs we eonsider the qualities of these two films and give a process whieh allows them to be simply developed into positives. Until a few months ago we have been using exclusively Kodak Miemfile AHU 6552 35mm film. This film is no mare expensive than regular black and white film and it is readily available in 1M)-ft rolls which can be easily loaded in cassettes to be used in any 35mm camera. The greatest advantage of this film is its high contrast and ultra high resolution (five times better resolution than the best color films). This high resolution can be extremely important for very detailed slides which are to be blown up in large lecture rooms. Recently, we have also been using Kodak's High Contrast Copy Film 5069. There are several advantages to this film besides the fact that it has almost the same high contrast and ultra high resolution of the Micmfile film. First, this film is readily available in 36 exposure 35mm cassettes, which makes it very agreeable to those departments whieh cannot use a 100 ft of film in a reasonable time or do not wish to bother with loading cassettes. This film is also no mare expensive than other black and white films. A second advantage of this new film is its clear film base. The brightness and color of the background will be almost solely that of the projector used to show the slide. Another very important aspect to recommend the use of Kodak's High Contrast Copy Film is its high ASA rating of 64 (tungsten), which allows shorter exposure times.2 This reduces the possibility of acoustical vibration lowering the resolution of the copied material. Next, we consider the development process which allows a positive image to be obtained from an otherwise negative producing film. For ease of use, we present this in the following table. After the film has been exposed and placed Reversal Process Stop I. Developfilmfnr 1 mininDeklol lundi1uted)orforbminin D~I9(undilucedIo Step 2. Rinw in running uater30-6(lsscb stop3
Step" St."S .~.?
.
step6.
Step7
Step8 step S. Step LO. step 11. Step L2. Stop 13.
Rleach l"r:i-.smin.".' .inso as instep 2.
i-lrr..ino " hathf".?-dmin .. ....... 0.c rims aa ln rrept.
Romovo reel fmm rank and erpoaecach m d of reel to photolamp for 15-30sec. replace rpel in tank.# Rodevelop in Dektol for 1-2 minorin D-19for5-6 min. Rinse aa in step 2. Fix for3-5 min" Hi"re~insten2. Ar8tarem hvpc1cleatineagentfor1-2min! Rinrefor5 minin runningwater.
" Temneraturen are assumed to he70'F for allsteos. althoueh thin is not critical. Refer to fllm dstashoet for information on temoeraturps.
~ " l y ' ~ i " itime ~ " is~ critical. c ~ o r m o l a for r bleach and clearing hnthr aregivenat theendofthis article. nf the film. Dependineon reel used. it ma" he n ~ c n s r yto remove the film from the reel m enso as to e ~ h &hould ~ he '"reexpasure. ,For the ,,mtection oftho slide a firer with a hardener should hevred. 'Step l l and 12 may be omitted. hut then the find wash must he lor 20-30 min.
on a reel and into a film tank, we proceed from step 1 through step 13 in the table. After the final step the film is rinsed in a wetting agent to promote quick drying. The total processing time fmm film in the tank to film dry in mounts is approximately 30-35 min depending an which developer is used. We would like to conclude by saying that with this method we have made many hundreds of slides with results as good as or better than standard processing laboratories and a t about a tenth of the cost. As a final note, this process can be used with normal films to achieve continuous tone positives of subjects other than graphic materials. !Solutions3 Bleaching Bath: Dissolve 5 g of potassium dichromate in 100 ml of water; then add, slowly, 5 ml of concentrated sulfuric acid while stirring constantly. Before use add water to make 1000 ml of solution. Clearing Both: Dissolve 50 g ofsodium sulfite (anhyd.) and 1 g of sodium hydroxide in 1000 ml ofwater.
Bmoks. D. W... Hedees. - , R. M.. and Philen. D. L.. J . CHEM. EDUC.., 50.566 . (1973). . . With two 500-W photoflood lamps at 15 in'. fromthe copy, a typical camera setting is f16 at ?sec. la 3Kodak Pamphlet No. F-101 (Aust.), 1971. These specific formulas are given only to cite a recognized authority. We have used quite different formulations with no change in the final result. 2
Faculty of Military Studies The University of New South Wales R.M.C., Duntroon, A.C.T., Australia 2600
N. Hamer L. Tog1 J. Tardif
Volume 52, Number 7, July 1975 / 447
