Ordinary water colours are best for stopping pinholes in negatives. Almost any colour will do; but the work is more easily and better done when a colour that matches. the tint of the negative is used, such as ivory black. The colour should be applied with a good sable brush, No. 2 being the best size. Rub a little of the paint on the smooth side of a piece of opal or even a piece of glass, and take up a little colour with the brush, drawing it with a circular motion to a fine point. If the b-ush is too wet the paint will run round the spot, and not in it. A white ring round a black spot only makes the spot more noticeable on a print. With the top of the brush touch the exact centre of the spot slowly but very delicately. In some few cases where the film has disappeared it is impossible to remove all traces of the spot; and in such cases it is advisable to fill in the spot densely on the negative, and paint over the white spot on the print. Exceedingly small pinholes, sometimes met with in clusters, are best left alone. A black spot ou a print is less noticeable than a white one. Spots are usually the result of dusty slides or camera or dark room, the dust being finally deposited on the face of the plate.

Soaking a plate in water before developing is liable with some plates to cause pinholes, the minute air balls that then form on the surface of the plate preventing the action of the developer.