Adding water "resistance" to quilts and sleeping bags

Having just returned from 10 days in Fiordland, NZ, fly fishing, one of my major gear issues was my quilt ( home made) getting damp from condensation from the tent. The tent issue is unavoidable, but I was hoping to find a DWR solution to my quilts, as both the quilt I used, and my winter ski touring quilt seem to have rather hydrophilic nylon!
Has anyone any experience with Nikwax/Grangers/Scotchguard ect as a means of reducing the degree that condensation soaks in to the outer fabric of quilt/sleeping bag?
It does seem to be an external issue, as outer surface of quilt was dry until I had to fluff around and get out of tent for a pee, during which the quilt touched the damp inner of the tent and got v damp.
A
Has anyone any experience with Nikwax/Grangers/Scotchguard ect as a means of reducing the degree that condensation soaks in to the outer fabric of quilt/sleeping bag?
It does seem to be an external issue, as outer surface of quilt was dry until I had to fluff around and get out of tent for a pee, during which the quilt touched the damp inner of the tent and got v damp.
A