Digital BW, The Print

Has anyone found a spray that will help harden the surface/prevent
scuffing of prints on matte or watercolor paper? My MIS-FS prints on
photorag, EAM, etc., will scuff, especially in the dark areas. I tried a
matte lacquer, Sureguard, but it muddies up the image, and reduces the
dark tone densities.

Thanks,
Steve