Recipe to remove pens/pencil marks from quilts

Another quilter shared this tip and I thought I would pass it on even though I have not tried it myself yet.
Read the instructions before you try it.

This is a recipe for removing pencil and other  marks.  

3 oz. rubbing alcohol
3 T. water
2-3 drops Ivory dish washing soap

Mix the ingredients together in a bottle. Put the quilt on an absorbent surface such as a beach towel. Try on an inconspicuous area of the quilt first. Apply solution with an old soft toothbrush but do not scrub unless the pencil marks are dark. Let the solution dry. Store in an upright bottle.