Macherey-Nagel qualitative indicator paper for whether a sample is alkaline, in 3 presentations covering different measuring ranges.
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A qualitative indicator paper that shows whether a sample is alkaline, by turning from red to blue. It gives a yes or a no, not a value.
The counterpart to blue litmus. Where blue finds acids, red finds bases: caustic carryover in a rinse, an alkaline cleaner still present on a surface, ammonia where there should be none.
A qualitative paper does one thing and does it without ambiguity. There is no scale to interpolate and no lighting to argue about: the colour changes or it does not.
That makes it the right tool when the decision is binary — proceed or do not — and the wrong tool when anyone needs to know how far past the threshold the sample is. For a value, use an indicator paper with a scale or a meter.
Keep red and blue papers in separate containers; once mixed they are indistinguishable after a sample has been run.
Supplied in 3 presentations covering different measuring ranges. The range is chosen by model: 8.0.