Excellent idea! Yet another use for sharpies!
Originally Posted by
Prism99
If it's machine quilting, you would have to be sure to leave enough on the ends to be able to hand knot and hide the ends. Leah Day has an excellent tute on her site that makes this easier by using a side-threading needle.
Personally, what I would probably do is find a Sharpie permanent marker in brown and simply hand color the thread dark brown in those areas.