LOCAL DEVELOPMENT The development of some portions of a negative to a greater extent than others. There are two methods of working, opposite in their character and effect. The first, which is more correctly termed " local development," consists in applying to certain parts of the negative a stronger solution than that in the dish, this being kept weak—that is, either dilute or containing but little alkali. The plate is taken from the dish, and some strong solution, kept separately in a measure, is applied by means of a soft camel-hair brush to the parts that are to be strengthened, taking care to prevent the strong solution from spreading or running tilting the plate may sometimes help in this connection. The negative must not be kept out of the developer for more than a minute at a time, and preferably less, there being always the risk of the solution settling in patches and of the developer in the film oxidising and causing stains. Therefore, it is best to brush the strong solution on the parts of the negative for about thirty or forty seconds, rinse the plate under the tap for a few moments, and return to the developing dish. After about a minute, the
local work may be repeated, observing the same precautions, and then again repeated as many times as desired.
The second method consists in developing the plate in a normal solution and then, from time to time, applying a so per cent. solution of potassium bromide to those parts that need to be held back, taking all necessary care as explained in the preceding paragraph. This method is frequently employed for holding back the sky part of a negative, so that clouds may retain their printing value.
A serious objection to these methods is that the plate has to be exposed freely to the dark room light, and it is almost impossible to avoid fogging. The photographer may decide, there fore, to adopt, instead, the methods given under the headings " Control in Printing," " Har monising Contrasts," or even to adopt local intensification or local reduction, although the local application of chemicals to negatives is not advised if the desired results can be obtained by other means.