Help, please! Would you use Sulky 40 variagated viscose thread for quilting? I've got some Gutterman poly which is just the right colour for my quilt backing, and some Sulky which is just right for the front - for FMQ. I've tried them out and they FMQ perfectly on my Janome but I'm worrying if the viscose thread is strong enough. This is a double bed quilt for my granddaughter and contains 28 photos of her from a few months old until just before her 18th birthday - so it's rather special! I've put so much work into it that I don't want to spoil its keeping properties! I know the quilt police say only use cotton threads. Will I be making a big mistake to use these two?