This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Commercial Ortho. There has been an increased demand from commercial workers for a plate suitable for reproduction of the grain of wood in mahogany furniture, dark oak, and bird's eye maple. Much practical experience led to the production of this emulsion. The plate has wonderful latitude and a lack of intensity in the middle tones which is so necessary in this class of work. It is so highly orthochro-matic as to render all the detail in yellow objects with very short exposure. Its keeping quality is most excellent. This is of the utmost importance in work where quantities of plates must be kept for some time and where increased contrast between the highlights and middle tones is necessary to good results. It has great latitude, works with vigor and is unusually brilliant. Speed same as 26x.
Process Plate. This is an emulsion of strong contrasts, especially suitable for giving black and white effects, for copying drawings, manuscripts, plans and printed matter. It requires six times longer exposure than the 26X.
Lantern Slide Plates. Our Regular Brand is made with the most perfect glass obtainable. It produces a rich black tone, very bright and crisp. It requires 5 to 6 seconds' exposure at 2 feet from a 16 c. p. lamp. Full directions for development in each box.
706. We recently added another slide plate which we have named the "Red Label" brand. It gives warm black or brown tones by a change in the developer, producing brilliant slides with beautiful detail. We offer this brand at a lower price than our regular plate and we predict that the quality and price will soon make it the most popular slide plate on the market. Full directions for exposure and development follow.
Black and Brown Tones. - Developer for Black Tones.
Seeds Sulphite Soda.
. . . 16 ounces.
... 2 ounces.
Bromide Potass ....
... 15 grains.
Take of No. I. - 3 ounces; No. II. - 2 ounces. Developer for Warm Tones.
. 16 ounces.
Seeds Sulphite Soda.
. 50 grains.
Bromide Potass ....
. 24 grains.
Potass. Carbonate. . .
To Develop. Take equal parts.
For still warmer tones the amount of sulphite may be reduced.
708. Exposure: As a guide we give the following example (taking a medium dense negative), if a 16 c. p. electric light is used the exposure should be about two seconds for black tone slides and three seconds for warm tones at a distance of three feet from the light.
OCEAN WAVES Study No. 14. See Page 346 J.S. Neary, Trenton, N. J..
709. It should be borne in mind that the results depend much upon the correctness of exposure, hence judgment and practice are necessary with the varying characters of negatives. If there is a doubt in the mind as to the time of exposure required for a certain negative, we would suggest that the aim be for under-exposure rather than over, for a slightly under-exposed lantern slide is always more satisfactory than an overtimed one, because of the indistinctness of the picture when thrown on the canvas.
710. To Develop: Temperature of developer should be between 70 and 75 Fahr., and if exposure and temperature of developer are correct the time of development will be about three minutes for either black or warm tones. To proceed, lay the plate face up in a suitable tray and flow the developer over it, allowing the developer to act until sufficient density in the shadows is obtained, then wash well and immerse in the fixing bath.
. . 64 ounces.
1 1/4 ounce.
Sulphuric Acid (cone.)
While stirring A vigorously, pour in B very slowly. This bath will keep, but should be filtered occasionally. The chrome alum bath recommended for our regular plates can be used, also fresh plain bath, hypo 4 ounces, water 16 ounces.
712. Leave plate in bath a few minutes after all white has disappeared from back. Wash well and then wipe surface gently with a wad of wet absorbent cotten. Rinse and set to dry in a ventilated place free from dust. Do not change position of plates while drying as it will show a difference in intensity with different conditions of air.