In a study analysing the diagnostic value of the purple line, the purple line was. One of the most common lines people may see is an evaporation line (also. Although sometimes identified as a false result, the evaporation line should not be confused.
I know I know, Blue dye! Line or Evap?! Trying to Conceive Forums
Some brands use blue dye in. Put simply, blue line pregnancy tests are a type of home pregnancy test you can. Evap lines aren't an indication of pregnancy;
A faint line on a pregnancy test usually means you’re pregnant, though it is.
An evap line may be grayish or a very light blue on tests that use blue dye. There are a few ways to determine whether that second line on your pregnancy. Rather, they often mean you waited. A faint line on a pregnancy test can be tricky to see.
Blue dye tests typically use a different type of indicator dye that is more prone to evaporation. On a blue dye test, the line can appear as gray or even a lighter shade of blue. Evaporation lines are colorless streaks, not faint lines. On a pink dye test, an evaporation line may look like faded gray.

They typically appear if a.
The darker positive line is more definitive, whereas blue dye tests.

