My 'Metamorphosis' challenge piece is backed with a bright colored fabric in which the stitching from the front can show through. Of course, now that means that the problems with stippling are showing through as well. They are even more obvious because I'm using a black top thread and orange bobbin thread. I've had a very difficult time breathing while trying to do the stippling tonight...not good! Its time to stop, then try again tomorrow.
Postscript: The problem was that the top thread was heavier than the bobbin thread. I've since changed the top black thread to a different weight black thread which is the same weight as the thread in the bobbin. The resulting quilting has not shown the kind of thread blobs as seen in the above photo.