the batting will help also keep the show through from happening- there are many different weights/weaves of muslins- i have backed quite a few black & white quilts with white- afraid the black would show through-it never has- unless you hold it up to light (which pretty much makes any top show through the back) prehaps put together a small practice sandwich- quilt it then check to see if it shows through- i believe there's a good chance it will not