The print may be immersed in this until sufficiently reduced, or it may be applied locally with cotton wool mop (as described above under platinum toning formula 18). The print must of course be quickly washed just before the desired degree of reduction has been produced. This solution acts somewhat quickly when once the action begins, and therefore it is well to deal with prints one at a time.
DEFECTS, ETC.
Red-orange patches are usually due to touching the gelatine surface with dirty fingers, etc. These places, being somewhat greasy, repel the various fluids and cause uneven action of the developing, toning, etc.
Brown Stains are also often produced in the same way. They may sometimes be removed by the application of a saturated solution of alum. If this fails one may try "chloride of lime" ("bleaching powder") one part in twenty parts of hot water. Allow to stand until cold and apply with cotton wool mop.
Yellow Stains may sometimes be removed by a dilute solution of potassium cyanide (poison) of strength one part cyanide in fifty parts water. (Yellow stains usually indicate hypo splashes.)
General Fog from Age.—This sometimes may be considerably reduced by giving the prints the bath of: Soda sulphite (one in fifteen) before toning, but well washing after this bath and before toning.
Very Slow Toning generally points to the fact that the toning bath is too cold, or that it has been spoilt by a small quantity of hypo or developer, or that it does not contain sufficient gold.
Uneven Toning, i.e., blue edges, generally points to a bath too strong in gold, or that there are too many prints in the bath at once, so that the edges are getting more of the metal than the central parts, or it may arise from prints sticking together or to the bottom of the dish.
Blue-Grey Tones indicate too long a time in the toning bath, or a bath too strong in gold.
Red-Yellow Tones arise from just the opposite state of affairs.