Cyanotype on Wood Tests

Tried printing on cyanotype on wood for the first time and it was really successful. I bought the wood panels Dollarama of all places (6 sheets for $5 is pretty good if you ask me). I have used thicker birch wood for making Van Dyke brown prints so I was a little skeptical about the thinness of Dollarama’s finest plywood. I tested exposure times at 5, 10, 15, and 20 minutes. It looks like 15-20 minutes seems like the sweet spot. The final washing took about an hour though, but I feel it was necessary since the chemicals absorb deeper into the wood verses paper. Unfortunately, the thinness did cause the boards to warp so they are not flat. I got suggestions to mount the pieces or use a frame, or even simply using a thicker wood, but I will sleep on it for now.