(I’ve seen this on the web here and there, but I first saw it in the fabulous book Summer Crafts by Marjorie Galen, which I bought in a used bookstore two years ago. The book was published in 2005, and Galen says as far as she knows, her friend Elizabeth’s family invented hot rocks.)
Materials: Rocks–larger and flatter are easier; peeled crayons; oven; nearby bucket of cold water (my plan-ahead self decided this was necessary, in case anyone accidentally touched the rocks)
Following the directions in the book, I preheated the oven to 350, lined a cookie sheet with tin foil, and set up my rocks (I did 8 this first time, two for each of us). Meanwhile, the kids began to peel some of our older crayons–I gather this is so as they melt against the rock, you’re not running up against the paper. Once the oven was hot, I baked the rocks for 15 minutes while we continued to peel crayons. When the rocks were almost done, I sent the kids outside with the crayons–I’d already brought a bucket of water to the patch of shaded driveway–and I met them with the tray of hot rocks. (Obviously, you want to place the rocks on a surface that won’t get burned.)
The rocks are hot. I made sure all my kids understood that they’d get burned if they touched them. G is two, and she did fine, but really, use your judgment with your own children.
I had the kids sit down, with the crayons in the middle, and using my oven mitt, I placed a rock in front of each of them. Then the magic begins.
“This is so cool!”
“This is so cool!!!”
I agree. I colored two rocks too, and it is so cool. And you can just keep adding wax and layering. Our rocks didn’t lose their heat before the kids were done experimenting.
The bucket of water did get a few uses, when fingers accidentally (or not so accidentally) bumped (do you see that inquisitive finger in the photo above?), but nobody got seriously hurt. It was definitely handy having the water there, though.
Look at those gorgeous rocks!