The cellulose dope is not compatible with the polyester fabric and, as it is nitrocellulose based, a little flammable. The base polyester is flame retardant 180gsm /6oz/sq yd so about what the canoe boys use. Aircraft would use a non cellulose dope, canoe boys a polyurethane based paint. But some use any household paint and it holds water. I will probably be looking to shrink it tight with a hot iron, as it seems to be what the canoe boys do and use a non shrinking but opaque paint otherwise the writing on the roofing membrane will show through. I thought of stenciling our logo on if it was a success.
Paint is quite expensive, for three coats (canoe grade) I would need about 2.5l. as the first coat needs to saturate the cloth. Floor paint is cheaper, but I have no feedback on its efficacy.