ISO 10349-7:1992 Preview
Photography -- Photographic-grade chemicals -- Test methods -- Part 7: Determination of alkalinity or acidity
This standard was last reviewed and confirmed in 2013. Therefore this version remains current.
The method is based on weighing the test portion, dissolution in carbon-dioxide-free water, adding phenolphthalein indicator, and observing the colour of the test solution: if the test solution turns pink, determination of the alkalinity, if it remains colourless, determination of the acidity.