Re: "serum of milk"
So we have now three types of whey: 1) from rennet coagulated milk, containing lactose and still some casein; 2) from strained yoghurt, with low casein content and whose lactose has been converted in lactic acid; 3) from acidified milk, low-casein and contaning both lactose and acetic or citric acid. This leads me to some questions: a) to which whey was referring Judy's recipe? b) what is the role of whey in that recipe? It looks like a mild seizing, because if you change whey with water you simply obtain a normal salted paper, or c) might lactic or citric acid play any role in sensitizing? As for a), I believe that the most common whey produced in large amount is the first type. As for b), perhaps some casein left in the whey is what is needed, so that the first type of whey is better. In this case, after sensitizing perhaps you will have also some silver caseinate, just as in albumen print you have silver albuminate. As for c), both silver lactate and citrate are insoluble. This would add additional ingredients to the recipe, but again I would prefer the first type of whey. Alberto
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