[Alt-photo] simple way of finding pH

Matti Koskinen mjkoskin at gmail.com
Sat Jun 6 07:56:33 UTC 2015


you may already know this, but red cabbage juice is quite accurate (and 
cheap)  method of finding what's the pH is e.g. of a paper.

Put half of a red cabbage in a blender, filter out the juice and put a 
drop of the juice on the paper. If the colour shifts towards blue, the 
paper is alkalic, if the colour shifts towards red, it's acidic.

Also a piece of white coffee filter paper soaked in the juice and then 
left to dry can be used to measure the pH of a liquid. My tap water is 
about 8.

I came across this, while googling  where to get lakmus paper for 
measuring tap water and the sodium carbonate liquid used in photopolymer 
gravure . Some pharmacies here sell it, but the price of it is x30 of 
the price of half of a red cabbage.



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