Verkkoan evaporation line on a pregnancy test is a faint, colorless streak that appears in the test's result window after the urine has dried. Verkkoin most cases, it’s not a true positive, but rather a very cruel and confusing phenomenon called an evap line. You may already know when to take a. Here's what each signifies on a pregnancy test, and how to tell the difference. Verkkoif the answer to these questions is yes, even though the line may not be as dark as the control line, it's likely a faint positive. If the line you're looking at.