Early Work In Photography
A Text-book For Beginners

94 Early Work in Photography. Another defect that will often be noticed is that known as "halation." This is most apparent around the windows of interiors, and about the tops of trees ana buildings where sky forms the background. This defect appears most frequently upon poor thinly- coated plates, and is due to the light having passed com- pletely through the film and thence been reflected back to the sensitive surface. After development it shows as a dense black deposit forming a halo and partly obscuring the objects surrounded by it. It may be removed by simple friction, thus : Stretch a piece of wash-leather tightly over a finger and moisten it with alcohol, place the perfectly dry negative film upwards on a solid bed—such as a piece of stout plate-glass---and then rub the dense portion vigorously with the leather and alcohol. Use plenty of pressure and gradually extend the field, so as not to leave too decided a mark. The leather will soon become black with silver, and the negative correspondingly reduced; this method is also “useful in other cases requiring local reduction. The prevention of “ halation” is better than its cure, and we advise beginners to use either " anti-halation " or thickly- coated plates, or, better still, an ordinary plate backed witli caramel and burnt sienna. The mixture is made by mixing one part of dextrine, two parts of burnt sienna and tliree parts of caramel (burnt sugar) with as little water as possible to make a very stiff paste; then thin it down witli methylated spirits. It should not be very thin or sloppy, but about the consistency of a starch mountant. The plate is placed face downwards on clean blotting paper, and a little of the backing composition is applied to the glass side and distributed by “ dabbing " witli a soft pad of linen, or by rolling with a roller squeegee. Very little is required to prevent all possibility of " halation,” and it is washed off easily with a damp sponge before development. Pinholes, and other clear marks due to dust and other causes, should be spotted out before prints are taken from the negative. A mixture of moist water colors (indigo and vermilion) applied with the tip of a round sable pencil is the best thing to use for this purpose. We do not intend to treat of retouching in this book, as that comes more within the range of advanced work, and there are several books de- voted exclusively to the subject; all we need say is that “re- touching"is principally done in lead pencil upon the negative film, which is previously rubbed with a " medium " (or var- nish) in order to give it sufficient " tooth" to take the pencil.