Macherey-Nagel
On demand
Macherey-Nagel qualitative indicator paper for strong acidity between pH 5.0 and 3.0, in one presentation.
90705
A qualitative indicator paper that shows strong acidity between pH 5.0 and 3.0, on a heavier, more robust paper. It gives a yes or a no, not a value.
The same Congo red chemistry on a stouter base. The heavier paper survives handling that tears a thin strip: a wet surface, a gloved hand, a sample that has to be wiped rather than dipped.
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.
Being thicker, it takes longer to wet through; give it the full contact time before reading.
Supplied in one presentation.