Verkkoa faint line on a pregnancy test may be a positive result or an evaporation line caused by dried urine. Learn how to tell the difference and what to. Verkkolearn how to distinguish an evaporation line from a faint positive on a pregnancy test, and why it matters. Find out what causes an evap line, how to. Verkkofaint positives on pregnancy tests appear within the reading window and are lightly colored, often indicating early pregnancy. Evaporation lines show up.