CYA: shake for 30 seconds (shake the whole time), then use. The black dot should be totally gone, no sign it was ever there.
TA: The color is read after swirling for a moment so the drop mixes into the whole solution. Add drops till it starts turning red/pink, continue adding drops as long as the color continues changing. When you add a drop and there is no further change in the color you are done, and the final drop that didn't change the color doesn't count.
TA: The color is read after swirling for a moment so the drop mixes into the whole solution. Add drops till it starts turning red/pink, continue adding drops as long as the color continues changing. When you add a drop and there is no further change in the color you are done, and the final drop that didn't change the color doesn't count.