Stephane, While I have never glued a soundboard with hide glue, I have glued large things, so, in my experience, it is very important not to apply the glue to cold surfaces. You will have more work time and a better joint if you gently heat the surfaces to be glued using heat lamps. I use those new portable shop-lights with the long cylindrical bulbs....they get very hot and the reflector is useful to direct the heat. I suppose the piano frame could be gently heated with a light underneath and a temporary cover over the top, like a large piece of cardboard or thin paneling. Just be careful of getting things too hot to scorch or flame up!! Just get them warm to the touch and you'll be fine. I also "size" my pieces with a very thin hide glue first...just a quick brush on of a very thin layer. It doesn't matter if it dries or sets....it will make the final gluing go on much smoother with fewer runs. So....heat, size, re-heat..then glue and clamp. Berley
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