We had days of 100-degree heat, then thunderstorms and rain. Neither one of these is very good for doing outside mosaics. The rocks were hit the hardest. We had to re-do and re-do and try different ways to get them to stay on the wall. After all, they were considerably heavier than the tiny broken grandmother's bowl. I finally got an idea: Let's use nails to rest them on! Well, thanks to Carlos (who was much stronger than I am), it worked. I'm not saying that he made it happen with great glee! I did hear him muttering a few things that I will not repeat here....if you get my drift!