It might be a better idea to do a first coat with just Tetrachloropalladate diluted suitably followed by a second coat with the regular Kallitype sensitiser. In this case also Silver Chloride is formed but is embedded in the fibres of the paper similar to what happens in Salt Print process.
Interestingly, there was a variant of Kallitype in America, unsurprisingly called American Kallitype, that a) used a metal additive in the sensitiser and b) took a salt printing like approach for coating.
From CASSELL'S Encyclopedia of photography, 1911:
American Kallitype. — In America much attention has been paid to kallitype, and many formulae and improvements have been introduced. The Jas. Thomson process needs a "salting" and a" sensitising" solution : —
Salting Solution
Ferric-ammonio citrate 45 g.
Ferric oxalate 27 g.
Potassium oxalate 27 g.
Copper chloride 13.5 g.
Oxalic acid 9 g.
Gum arabic 22.5 g.
Distilled water 1,000 ccs.
The paper (sized if velvety tones are desired) is coated with the above, dried, and treated withthe sensitiser : —
Oxalic acid 4.5 g.
Citric acid 45 g.
Silver nitrate 112.5 g.
Water 1,000 ccs.
When surface dry, complete the drying by gentie heat, but excess of heat will convert the ferric salt to ferrous. For printing, three or four minutes in sunlight is generally sufficient. The image appearing is chestnut brown upon a yellow ground, and printing should be stopped before the half-tones appear. The print is placed direct into clear cold water, where it will develop fully; four changes of water, or about three minutes in running water, will be sufficient. After washing, fix in a weak "hypo" bath (50 grs. to 32 oz.); a ten-minute immersion is generally sufficient. Wash in plain water for about half an hour and dry; the resultant colour should be a good brown.
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No idea if there are any contemporary practitioners of American Kallitype printing process though Dick Steven has tried some of Thomson's brown print formulas and makes interesting remarks on them in his book.
