When I save my scraps from cutting out quilt squares, I sort them by color into plastic shoe boxes. Therefore, my scraps are never all mixed up. I do not consider a scrap quilt to contain new fabrics purchased just for that quilt. Scrap quilts would contain leftovers from other projects, and pieces perhaps given to you that others had leftover. Also, scraps are all peices too small to use making a full quilt block, I'd say smaller than 1/4th yard or maybe 1/8th of a yard. So the color is not important in a scrap quilt, as mine could be all pink if I use just my pink scrap box. It's the size of the piece and that it's not bought new for the project.