A negative result is read when two distinct red lines appear, one in the control region (C) and another in the test region (T). Do the two lines need to be of the same intensity?
No. The intensity of the red color in the test line region (T) will vary. Any shade of a red line in the test (T) region (darker than, the same color as, or lighter than the control line) along with a red line in the control (C) region is considered a negative result.