We assume you're asking how it works when putting drops that change color to show pH into a non-clear liquid. Use a small amount of test liquid and watch very closely in the light when the drops hit the liquid sample. A magnifying glass may help for some. The drops change color as soon as they touch the liquid and you can usually see the color before it completely mixes with the sample. Another way to help see the color is by diluting the sample 100% (a 50/50 mix) with pure pH 7 water and double the difference between 7 and the reading. For example, you dilute a sample 100% with pure water and get a pH reading of 6. You then figure the sample is pH 5 because an equal mix of pH 7 liquid and pH 5 liquid should yield roughly pH 6 liquid. Alternatively, you can try adding more drops to a sample for a stronger color. The sample can also be put on a white surface with some of the pH drops next to it and the two aren't totally mixed but slowly moved around together while you watch the colors.
