Metabisulfite of potash
Potassium pyrosulfite
pyrosulfurous acid, dipotassium salt
Disulfurous acid, dipotassium salt
Potassium disulfite
acidifier used in fixers and stop baths.
-Potassium permanganate - chemical used extensively in reducers, bleaches and toners.
-Potassium persulfate - chemical sometimes used in super-proportional reducers.
| Appearance | Transparent needle crystals or crystalline powder Odor of sulfur dioxide |
| Uses | As a preservative in developers Used in place of sodium sulfite in some developers Used for acidifying fixing baths |
| Chemical Formula | K2S2O5 |
| Notes | Replaces sodium bisulfite weight for weight. Deteriorates rapidly in air. |