Test the fabrics to see if they need pre-washing. Wet a corner, put it between 2 pieces of paper towels, put weight on a plate on top of it ( books) for about half an hour. If color doesn't transfer to the towels, no need to prewash. If color does transfer, you need to prewash AND should probably use color grabbers - re-wash until no color shows on the color grabbers. Food for thought - a wallhanging won't be washed very often - if ever, so little or no worries about color transfer. A table topper MAY be washed, so think about color placement. Is the color that shows on the towel going to be next to a lighter color? If it isn't, a color grabber in the wash load should be enough, and you don't have to pre-wash.