The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Bromide Paper
dense and harsh negatives a rapid paper should be chosen, for thin negatives a slow paper ; the former may be exposed a very short distance from the light, the latter a longer distance. For all bromide contact-printing artificial light should be used, either gas or magnesium. Commercial bromide paper is sold of various rapidities, and a few trials will enable the photographer to judge as to sensitiveness. The important item for successful results is correct exposure, and the simplest method of ascertaining this is the following: - The standards used are a No. 5 Bray burner turned up to its fullest extent without flaring, a fixed distance for exposure from the Bray burner, viz., two feet, a fixed scale of feet from the burner, or a six-foot inch tape, and lastly a piece of flashed opal, smoothed or ground on the opal side (any size may be used, but about half-plate will be found convenient). The opal glass is placed in contact with the film of the negative, and the two held up before the gas burner, the negative being next the operator, at the full length of six feet from the burner. Now examine the image, and approach the negative nearer the light till the details, such as the markings on a brick or stone wall, or the trunk of leaves of a tree, just become visible. Note the dis-tance between this point and the end of the inch tape, and give an exposure corresponding in number of seconds to number of inches - for instance, the details of negative become visible 36 inches from the six-foot mark ; therefore 36 seconds exposure will be required for that particular negative at a distance of two feet from the burner. An alternative method is to cut little strips of bromide paper, and place one in contact with the half-tones, and a deep shadow of the negative, and give the strip an exposure; then replace by another strip, and give a longer exposure; and then repeat for a third time. On development it is easy to see the correct exposure. The first essential for development is of course a developer; and for enlargements the old ferrous oxalate still holds a place, though many operators now use quinol or eikonogen, synthol, amidol, or one of the newer developing agents, or a mixture of the two. The formula for a good all-round ferrous oxalate developer is as follows: -
Neutral oxalate of potash ... ... ... 6 ozs.
Distilled water         ... ... ... ... 25 ,,