Always read the results at 5 minutes, if you read the results too early the test may not be finished reacting. Although a positive result should not change for several days, a negative result can change to a false positive within minutes after the end of the testing period. The faint or shadow lines that have no color is where the reagent is applied to the test area. You will see reagent areas on any test if you look hard or make it wet. This is how reagent strips work: If there is HCG hormone in your urine it will react with the reagent on the strip and the line will change color. You should disregard any lines that have no color or haven't changed color.