Color of Slate
How do we play with the color of slate? On roofs we vary the color an mix of color and rely on the vein of slate to last until the roof is complete. A roof, however, is not the only place to use slate. It can be used on walls and floors as well. Slate is split and can come in any size or shape. It is a stone with a grain so surface texture is often apparent and a desired quality.
My first sample is a Gray slate sample with a Sandblast finish. The process of sandblasting has moved the value towards white. The stone now has a stippled texture to it which hides much of the inherit fluctuation in its coloring.
In the second illustration, the gray slate was Flamed. It was heat treated after it was cut and the results show an increase in color. It has brought out the red, a hue created by the iron within the soil. When compared to the above, it is almost pink. The slate and the granite behave similarly during the flaming process.
The last example I will show is a Gray slate with a Honed Finish. The slate has become smooth to the touch and sparkles in the sunlight, although it is not reflective. The color of the stone on the value scale has jumped towards the gray, but in the sunlight it appears almost white.
Outcome
So it seems if you desire the stones natural colors to be brought fourth, you must do as mother nature did, heat the stone. The Flaming process, as we have seen, subtly bring out the stones colors. A rougher surface will tend towards the black end of the value scale while a honed finish will tend towards the white end. Next time you pass a building, note the banding and coursing of the exterior if it is stone. Chances are it is the same color of stone, only cut and finished differently in order to contrast. Enjoy designing with the material, remember its age and treat it kindly.