Platinum Toner.
Platinum
toning gives enhanced black images. This method uses Platinous Chloride (
PtCl2 ) in the presence of an alkali chloride which gives a chloroplatinite
e.g. PtCl2.2KCl. The platinum is displaced by the silver within the photographic
image from within these compounds. This is then precipitated as a metal whilst
the silver is converted to a insoluble halide: PtCl2 + 2Ag = Pt + 2AgCl.
The reaction
has to take place in an acid solution. The preferred platinum salt is potassium
chloroplatinite. The toning process leaves approx. 25% of the image silver
unaffected.
| Potassium Chloroplatinite
- 0.5g |
| Phosphoric Acid -
10cc |
| Water - 1000cc. |
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