I mixed some glypho concentrate with some AG NIS and blue colourant, with the idea that it would help me more thoroughly hit the weeds in my gravel ditch. What I forgot is that I typically use my glypho tank to also do weeds in the cracks of my interlocking brick patio and concrete front walkway. I expect the colourant will stain a bit, but is it likely to be permanent? If not I'll endure some blue marks in these areas until I use up this concrete staining raleigh tank and not add colourant to the next batch. Otherwise I guess I gotta buy another tank or hand pull weeds for a while.