Except in special cases such as fire scenes, sunset and moonlight
effects, and the like, it is very undesirable to employ strong tints,
since apart from the displeasing effect and irritation to the eye,
the dyes produce a slight softening of the gelatine film when used at
80 degrees F. in 1% solution.
Should it be necessary to employ concentrated baths in summer,
either cool the dye-bath or use a suitable hardener. This will
be unnecessary if hardener is employed in the fixing bath after
development, but otherwise if formalin (40%) be added to the dye-bath
to the extent of 1 volume to 400 volumes of dye solution, no trouble
will be encountered. During the winter months, when it is advisable
to treat all film after developing and fixing, with glycerine, the
latter may be incorporated with the dye-bath, thereby eliminating
an extra operation. The strength of the glycerine should be 2%, or
two volumes per one hundred volumes of dye solution. In most cases,
however, the addition of glycerine considerably retards the rate of
dyeing, so that in order to obtain the same degree of tinting within
a period of ten minutes, the concentration of the dye-bath should be
increased accordingly.
When delicate tints are employed, the effect is both to remove the
contrasty black and white effect, and to add a touch of warmth to
the black deposit of silver, even in cases where the highlights are
insufficiently stained to be noticeable. The result in many cases is
equal to that obtained by partial toning, for example, tint No. 11
gives the effect of a blue-black tone.