since i determined that the cotton crochet potholder did not do a sufficient job, i prepared to add a backing. i ran it through the washer/dryer and it did shrink about an inch in width. unfortunately the yarns i used don't hold up that well to washing and it already looks a bit ragged.
i cut 9" squares of insulbright and quilting cotton and quilted wavy lines with some guttermann thread. then i cut out a circle, put a white cotton circle on top and stitched a quarter inch around leaving an opening. then i turned it rightside out and topstitched. finally i stitched the quilted circle to the potholder.
i'm very happy with the outcome. it looks great in our kitchen and works quite well now. i like that it still has that old-fashioned kitschy look i was going for. i'm not quite done with my potholder experiments, so there will be more to come.