I used a similar concoction for while, white lithium grease with white pigment/colorant from the paint store. Worked fairly well, but eventually got crusty/dried up from the high winds and dust in West Texas. So I got a great deal one time on ebay for 36 1 lb tubs of Castrol wheel bearing grease in dark amber. While not as easy to see the pattern from a distance as the white stuff, I still have to walk back to the patterning board to "clear" it, and then the pattern is plainly visible a couple feet away. When it gets crusty after a couple months, it's just scraped off and new grease applied.
Mike
