Marcia, since you have used the WOWs with your other blocks, I don't see any problem in using it for sashing. Maybe that particular block you tried it on looks like it's clashing, because that block has a cream neutral instead of white. But overall, I think the WOW will fade into the background and let your blocks sing! At least you don't have to worry about it just yet. Still plenty of blocks to be made first.