Hello Charles
First…thanks for the post.
Next…I use White. I have a couple of reasons.
First…yes…you can see it on concrete. No problems there.
Next…when you spray over a color like blue or red…that color will bleed through. I know that sounds minor but…you’ll see it. You’ll have a nice, white 4″ line…and a real pretty, skinny blue line that bled through.
Next…the last reason is mine…all mine…color is dye. It split my fingertips…!
I was out one day. I stopped at a small hardware store and bought “half moon” blue chalk. After a while my fingertips split…no big deal…but it was like paper cuts in my finger prints. I’m not sure of it was the dye…all is well.
Friend…I use white.
How’s all that?
I hope helped.
Let me know.
Dan