An Iridiotype Supreme is a photographic print formed from an admixture of iridium chloride and platinum chloride, palladium chloride, or gold chloride. While Richard Puckett has succeeded in printing out two photographs in pure iridium, the process eludes repeatability. However, he followed on the invention of the Rhodiotype Supreme by systematically testing print out of iridium with the smallest possible amount of palladium. The final minimum proportion of platinum or palladium or gold to iridium was 25% precious metal and 75% iridium. A curious discovery arising from this combination, and the attempt to replicate the Rhodiotype substituting iridium for rhodium, was that the iridium apparently protects the palladium from dissolution by hydrochloric acid. In the presence of iridium, palladium does not dissolve in strong acid. As a result, pending further research on print out of pure iridium, it is necessary to mix a sensitizer that is at least 25% palladium (or other precious metal). More palladium in particular smooths the image, with roughly 40% palladium to 60% iridium the ideal compromise of quality and fidelity to the concept of the iridiotype.

1. Prepare 10 ml of a solution of ammonium ferric ferrous oxalate or sodium ferric ferrous oxalate (refer to the book 21st Century Alchemy for information about sodium ferric ferrous oxalate).

2. Prepare a solution of 15% iridium (1 gram of iridium chloride hydrate dissolved in 6.5 ml of distilled water at 85F).

3. Prepare a solution of 15% palladium (1 gram of sodium palladium chloride hydrate and 0.5 gram of pure sodium chloride dissolved in 6.5 ml of distilled water at 85F).

4. Count the necessary drops of affo or sffo into a shot glass. Four drops for a 4x5; 16 for an 8x10. Etc.

5. Count at a number of drops, equal to at least one-quarter of the total and less than one-half, of palladium into the shot glass and swirl to mix.

6. Count as many drops of iridum chloride into the shot glass so that the total number of drops of metal equals the number of drops of double ferric ferrous oxalate. Swirl to mix.

7. Pour the sensitizer onto a sheet of paper (Revere Platinum, Bergger Cot, Hahnemuhle Platinum, Rives BFK, Clearprint 1000H vellum) and brush it across the area to be printed.

8. Place the senstized paper in a dark place until dry. 

9. Place the paper and a negative together in a contact print frame and expose to UV or sunlight. Drop the contact print frame back from time to time to observe print out progress.

10. Immerse the fully printed out paper in a tray of 0.5% hydrochloric acid for 15 minutes.

11. Wash the cleared print in cool running water for 45 minutes.