I noticed a tension issue show up when my threads didn't match front and back, and one was much different than the predominate color of the fabric. Not sure if it was my technique on FMQ or what. I had it into the shop twice without any resolution. (they told me I was using 'cheap' thread) Very frustrating! And, why is it that you can get super results on your practice piece..and without changing a thing, you move to your quilt and it all gets wonky!?! I do like the varigated threads too. Hope you'll post a picture when you are done! (I hope this didn't sound too negative, just wanted to warn you of a problem I recently had...)