In my search for finding a way to get flat fibre prints, I tried the suggestion to dry mount a test print to the back of a finished print, and I discovered last weekend that it works remarkably well. The result is much stiffer than I would have imagined and the print stays flat. I don't have an expensive dry mount press. I bought some mounting tissue (
DuraCraft DuraMount Dry Mounting Tissue ) and use a clothes iron.
So far I have only mounted the test print with the emulsion on the outside, but I don't see any problem with mounting the test print with the emulsion hidden. If you're so good that you don't have a large enough supply of not good enough prints, you could buy some heavy card stock.