Platinotypes may be toned to a red-brown by uranium nitrate, or to a bluer colour with chloride of gold. They may also be intensified by pyrogallic acid or hydroquinone, but as the purpose of this article was merely to give simple working instructions for platinotype printing for the beginner, he may defer the consideration of such side issues until he has become au fait in the production of a good platinotype print.
A. Horsley Hinton.
Contact Printing on Bromide Paper.
It is well to bear in mind at the outset that bromide paper is extremely sensitive to light, almost as much so as is a rapid dry plate. For this reason, it is obvious that it must not be carelessly exposed to actinic light. All manipulations except the actual printing must be conducted by red or yellow light, such as is allowed to pass through glass of these colours.
For evenness of result, it is better to use a lantern than daylight, because the fluctuation in intensity of the latter is very misleading and liable to lead to failures through over or under development.
The actual colour of the light, also, is of far more importance than one would suppose: ruby light tends to give one the impression that development is complete long before that is the actual case; it is also somewhat more difficult to handle the paper satisfactorily by this light than by a good yellow.