01
Compare under consistent conditions
Set candidate samples beside one another and photograph them in the same light. Look at dry surfaces first, then compare the appearance when wet if practical. Avoid comparing one damp sample with another that is dry. Phone cameras and displays can shift color, so use photographs to record a comparison rather than treating them as a precise color standard.
02
Return to the building
View the samples alongside the wall materials and from an angle that resembles the roof's presentation. A close tabletop view emphasizes texture differently from a roof seen at street level. Keep notes on which appearance you approved and ask whether the sample represents the expected range. The purpose is a deliberate selection, not a promise that every piece will look identical in every season.