Update: After the first rain, the brim on the scarecrow’s hat was flexible, so it absorbed water. It wasn’t sticky, like it was before the clay dried, but it wasn’t solid, either. At this point, I recommend that you read up on the two experiments shown on this site that did actually work: Julie’s mountain lion, made with Quickwall cement over paper mache clay, and Jackie’s Goddess, made with thin set tile mortar over paper mache clay.
The paper mache clay Scarecrow sculpture finally got his final coat of the Trojan Masonry and Concrete Sealer, and now we wait and see what happens. After I poured all the over-sprayed sealer back into the container, I could see that I only used a few cups of the product. If this works, there will be plenty left for other projects.
I suspect that the best protection would be a combination of products: the penetrating sealer first, then paint, then a good UV-resistant outdoor varnish. I know many people have used the spar varnish alone, without the sealer, and have good results. That wasn’t my own experience, so I can’t recommend it – but it’s possible that I used a brand of varnish that didn’t resist the sun’s rays as well as the brand that others have used. And, of course, I didn’t write down what brand I bought. My bad…
I’m getting excited about outdoor sculptures, and I ordered several books about sculpting with concrete. I’ll do some experiments with the recipes and techniques I learn, if you all happen to be interested. Not really “paper mache” related, but I think it might be fun to learn.
But for now, wish our friend Scarecrow luck – we have a few more storms on the way, so it might not be long before we find out if this experiment worked or not. If it looks like the sealer really is working, I’ll go ahead and coat him with the Sculpt Nouveau iron coating so he’ll look like a cast iron sculpture, and then find a permanent spot for him in the garden. He’ll look a lot better if that white bucket is buried in the ground.