muslin make wonderful quilts- many people I know always back their quilts with muslin, either bleached or natural- it washes up nicely becomes softer & softer with wear & laundering and is a wonderful inexpensive utility cotton fabric. their are many different *grades* of muslin, some are quite thin, loose weaves - which do tighten up some when pre-washed- and make good foundations for foundation/paper piecing- some are much heavier- some almost as heavy as any broadcloth. muslin has been used in quilting since the 1700's (maybe even earlier) the difference between a bleached muslin and a solid white fabric is---muslin is a natural cotton fiber that is a tan-creamy color- it is bleached to make it white- white solid fabric is made with white threads woven together. muslin also dyes beautifully- you can purchase it generally for a lot less than other solid fabrics then dye it any color you want it to be if you want to.