Julie
Sorry, but I have bad news: Regular pencil does not come off fabric! I think almost every quilter learned it the “hard way”. :( You can use a graphite pencil (art supply store) but, just in case, I always try in a small piece to make sure it comes off.
Other things you can try to mark quilts are: soap stone pencil, color pencils, pencils sold as markers in quilting stores, ball point pens :shock: , crayolla washable markers :shock: and my favorites, chalk markers (if you mark as you quilt) and hera marker :) . I had a bad result with blue chalk! I know some of these sound crazy, but it is much easier to wash a ball point pen mark than pencil. The bottom line, as I mentioned above, always try in a small piece of the fabric you will use on and wash it before using it in the quilt top!
I used pieces of muslin and made samples of all the things that I can use; I mark 2 pieces and wash one. Then I file both of them and that way I have an idea of what I can use in the future.
Hope this helps.
Lucia