Litmus Paper, PH 1 / PH 12 from Netherlands (SKU 1649)
1. Dip test strip into solution, in direction of arrow, for roughly three seconds, so that all colour zones are immersed. 2. Compare indicator zone (unprinted area) to colour scale and read off printed pH value. By holding strip against light, the pH determination may be facilitated.
This is a series of pH indicator papers where the indicator and colour scale are combined on a single strip. They permit a fast, convenient and accurate pH value determination since they eliminate the necessity to compare colour against scale. This presentation also permits the pH measurement of colored solutions and suspensions, since the colour of the test solution acts on the comparison scale in the same manner as on the indicator field. The individual colour zones are separated by hydrophobic barriers.
The PEHANON® series covers the entire pH range from 0 to 14 with one universal paper and thirteen narrow ranges which overlap to permit utmost selectivity for the range suited to each particular need. The pH gradations within each strip have been established to offer maximum colour differentiation from one comparison field to the next depending on the individual indicator.
The indicator zone (unprinted field of 6 mm width) is in the centre of the strip, the comparison fields (4 mm wide) above and below same. The strip is submerged in the solution for about three seconds so that all colour zones are wetted whereby the centre field changes colour according to the pH value of the solution and is then compared against the colour field bearing the corresponding pH value imprint.
An invisible hydrophobic barrier just above the top colour field prevents capillary action of the test solution beyond that point and corrosive, toxic or otherwise noxious liquids do not come in contact with fingers which remain clean and dry.