Pulled out the jar of Polyacrylic and applied two coats to the top of each placemat. This is the first I've used this product on a fabric base. I was surprised at how flexible it remained. I suppose I thought that Polyacrylic would make the mats somewhat stiff.
I'm going to put these on the table tomorrow and we'll start some stress testing. (although I'm not expecting any issues).
In a day or two, I'm planning on cutting some more canvas and giving this another try. I like that idea that other than the decision of the initial color that goes down, the rest just happens ... good design or bad.