para-rodinal question

[marcsv]

what are the crystal deposits at the bottom of a brew of para-rodinal? can this be used in another developer formula?

 

[Gerald Koch]

If you are talking about the p-aminophenol developer made from paracetamol (acetaminophen) then it is hard to say since the composition of the tablets varies among the different manufacturers. That said, the crystals at the bottom of a conventional pap developer consist of p-aminophenol base. The reason that they are there is that the developer slowly absorbs carbon dioxide from the air causing the free base to form. This compound is only slightly soluble in water (< 0.1 g/100 ml @ 23C).