The answer isn’t a simple yes or no, even though it should be. According to most home pregnancy test kits, any second line, no matter how faint it may look to you, means the test is positive. The problem with this explanation is that it’s only true if the line appeared within the test limit (that means, for most tests, the line needs to appear within five to ten minutes of exposing it to urine). That’s because sometimes, something called an “evaporation line” can occur when a used pregnancy test begins to dry. This line is simply the indent where the test line would have showed a positive result, it doesn’t mean you’re pregnant, it just means that your urine soaking into the test has made the indent visible.
If your test looks negative and you trash it and then pull it back out hours later to look at it again and find that it has a faint second line, it could very well be an evaporation line, not a true positive result. An easy way to tell the difference between a true faint positive line and an evaporation line is whether or not the line has color. If you’re taking a pink dye test, this faint line can still be considered positive within the testing limit (those first five to ten minutes) if it looks pink and not gray. Likewise, with a blue dye test, this second line, no matter how faint, needs to have a blue color to it in order for it to be considered positive. These blue dye tests can be tricky to interpret as gray can sometimes look blueish and vice versa.
So, simply put, if the second line is faint but still shows up within 5-10 minutes of taking the test and has obvious color to it, yes it’s positive!