What is an “evaporation” line on a pregnancy test?
An evaporation line develops when the urine on the test area begins to dry, leaving a faint, usually colorless line or very faint colored lines. Many tests give an evaporation line after the specified time for results. If you the directions on your pregnancy tests say do not read after 10 minutes of throw away after ten minutes, any line that shows up is NOT reliable. You must read it at the specified time.