Putting color in Portland Type II Cement to fill the joints between flagstone is not a good idea.
Joe from California asked:
I am putting in a flagstone walkway on a concrete base. I have layed the stones using a type S mortar to set in place. My question is what type of colored grout shoud i use?
Dear Joe, We never recommend using color. We have never seen a color in bricks or stone that lasts more than 2 to 3 years. It streaks too much after the sun tears it up. Indoors coloring works well, but not outdoors. We just got done talking to a landscape architect and he says he never will use coloring.
I will be doing more of the latest research on flagstone, so maybe there are some products out there that don't streak any more. Make sure to sign up for my free newsletter below and I'll inform you about anything that I hear.
Hope that helps,
David and Hans