Know Your Substrate!

I mosaicked this gecko as part of the 2010 Geckofest for Bradenton, Florida. Every two years local artists are invited to paint or decorate a gecko (they are 6-foot fiberglass forms) to be auctioned off for charity. They are mounted in various spots about town for several months before the auction; mine is shown (in happier times) on the side of the South Florida Museum where it lived last fall. Its feet are painted, but the rest is shells, glass gems, and blue/green/white tiles of various sizes. It's name is "Flotsam Gecko."

Unfortunately, this spring, after the gecko was purchased at the auction, tiles started falling off! I repaired small portions twice, but last month, after it happened again, I brought it back to my studio to completely redo. This was my first time working on fiberglass. I had used exterior thin-set, which usually sticks to anything like a rock, but apparently it is not suitable for fiberglass. I'm currently in the process of completely redoing the job, having learned a valuable lesson about substrates. I'm now only using adhesives that are meant for fiberglass, so they have some flexibility. I also reinforced the form on the inside with spray foam; I think part of the problem is that the form was not completely stable and rigid, so it's more likely to crack a rigid adhesive like thin-set. Finally, I roughed up the surface with sandpaper, a wire brush, and a nail. Live and learn!