I used a blue water soluble marker (and made an amazing mess in some areas) to get the main designs onto the white background. As I went along I sprayed the Wholecloth with water to get rid of some of the lines as I find them quite distracting when stitching.
It is winter here and not the ideal time to wash quilts, however I felt uncomfortable leaving this as I have seen in the past how these blue spots can turn slightly brown over time. With a whitish Wholecloth, not a good idea. So, on the weekend we had a bit of sun and my quilt took the plunge
After that I had it outside on a flat surface for a while to get it to a stage where it was reasonably damp and now it is nicely blocked, taking up some space in the kitchen area. This will take a few days to dry in this climate and I will just have to make sure that the cats stay off it.
So while the temptation is there to just spray the blue water soluble markers off I would urge others to wash their quilts after finishing...just not worth the hassle after. I had a few brownish marks in one of my pieces recently and I thought that this probably happened as I had just sprayed my designs and then left it sitting on the sewing table where it would have gotten a fair bit of sun in the day...that was enough to set the marker.