It is important to remember that slate is a completely natural material. That means the color will inherently be varied and will react with nature. This is particularly important to know when choosing a slate roof color. Here are some terms that will help you understand how your slate roof color will evolve:
Weathering, Semi-Weathering and Non-Weathering Slate
When a slate is described as “weathering”, it means that the slate roof color will slowly change from its original color into an earth tone. This naturally occurs due to an oxidation of minerals in the slates as they are exposed to the elements, like rain and sun. Weathering slates will change color the most. With Semi-Weathering slate only about 15-20% of the slates will change to tans, or buffs, not the entire roof. Non-Weathering slates won’t change much, if at all.
Fading and Unfading Slate
The difference between weathering and fading, is that slates that fade don’t actually change color. Instead, fading slates develop a chalk-like residue that makes the slate roof color appear to have faded. An unfading slate does not develop this residue, and will generally stay true to color.