I saw this picture the other night and read that they cut open glow sticks and poured the liquid out on their steps. I was wondering if anyone knows whether or not the liquid inside glow sticks will stain concrete or clay tiles. I would like to mark my outside porch steps so that people don't trip. This is a much cooler effect than having the steps lit up with a spot light. Also, do you think that it would still glow once dry?