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|
| Part A | ||
| Distilled water | 300 | ml |
| Ferric Ammonium Citrate | 21 | g |
| Ferric Oxalate | 10.5 | g |
| Potassium Oxalate | 21.7 | g |
| Copper Chloride | 2.6 | g |
| Citric Acid | 2.6 | g |
| Silver Nitrate | 6.5 | g |
| Oxalic Acid | 6.5 | g |
| Gum Arabic | 6.5 | g |
| Part B | ||
| Distilled water | 30 | ml |
| Potassium Bichromate | 1.3 | g |
| Mixing Instructions: Mix into amber glass bottle, adding chemicals in specified sequence. Store in dark place for 24 hours and then filter to remove all gritty particles. |
| Dilution: Add 1-10 drops of Solution B per 30ml Solution A for average negatives. Increasing the amount of Solution B increases print contrast. |
| Usage: Apply smoothly to paper with soft artist brush (eg. camel hair) - do not use a brush with a metal ferrule. Do not let sensitizer come into contact with metal. Softer papers may require sizing. When surface dry, complete drying by heating (eg. with hair dryer) for best results. Print by inspection until shadows appear deep yellow. |
Notes This is the original James Thompson formula from 1904. The ferric ammonium citrate used at the time was in the form of brown scales. For historic purposes, you should use brown Ferric Ammonium Citrate; however, most modern users are happy to substitute the more common green version. WARNING: Silver Nitrate is hazardous and staining to skin and material. Wear gloves at all time to avoid skin contact. Ensure respiratory safety when handling. |
