The Palladium Solution
An equimolar solution of palladium is made relative to the platinum solution. The most economical method is to use palladium chloride (PdCl₂) in combination with sodium chloride in solution. 3.5 grams of sodium chloride are dissolved in 55ml. of warm distilled water and then 5.0 grams of palladium chloride are added and stirred until dissolved. Stored in a brown glass bottle, it has a long shelf life.

A mixture of platinum and palladium salts has advantages over either platinum or palladium used alone -- most notably a consistency of printing (contrast, speed, and color) over a range of relative humidities and temperatures. It is convenient at this time to mix equal amounts of platinum and palladium solutions to make a single solution that is added to an equal amount of ferric oxalate prior to coating on the paper. This will also prevent the platinum from crystallizing out of the solution as it cools. The ratio of platinum to palladium can be varied to affect print color, palladium being much warmer in tone than platinum. The palladium solution is also about 1/4 of the price of palladium and when used with an equal amount of platinum and developed in the developer described later results in slightly warm-black print color.

The Ferric Oxalate Solution
This is the light sensitive agent and hence the most delicate of the compounds that is used and should be protected from ultraviolet light and excess heat. It is also the most difficult to dissolve. To mix, 100ml. of distilled water is placed in a red glass flask and warmed to about 100 degrees F. In a separate room with good ventilation 27.0 grams of ferric oxalate are weighed out under incandescent light (wear your dust mask) and transferred to the the warm distilled water. Now you can go back into the darkroom and keep it warm while stirring until it is dissolved. Stored in a brown glass bottle it will keep for 3 or 4 months if prepared in this manner.

Those familiar with platinum will notice the absence of several ingredients as compared to the classic recipes in normal use. Potassium chlorate, an oxidizer, is and has been used to to increase contrast in the platinum emulsion, but has several drawbacks -- instability and increased print graininess with increased contrast levels. It also necessitates the use of two oxalate solutions, one with and one without chlorate which are mixed in various proporations to control contrast, traditionally with the inherently inaccurate "drop" method of measurement. Also left out is the oxalic acid from the ferric oxalate solution which was believed to add to the richness of the blacks in the print.

Contrast Solution
3% hydrogen peroxide, available at any drugstore in ready to use form. When added to the sensitizer solution it does not have the increasing grain problem associated with potassium chlorate.

Developer Solution
This is a variation on several of the traditional "cold tone" room temperature developers utilizing potassium oxalate and a phosphate, with the exception that this formula contains a buffer system to regulate pH. Into a liter of warm distilled water dissolve 140 grams of potassium oxalate, then 20 grams of dipotassium phosphate, followed with 5 grams of oxalic acid. Dilute with an equal amount of distilled water and use half for developing and the other half to top up your developer as it gets carried out with the prints.