Before you get too into buying a new chair or a back brace - you need to make an ergonomic evaluation of your sewing station. If you "The Back Store" in your area you might go in go in and see what they recommend for a chair. Better yet meet with a occ. therapist - a referral from a doctor is needed for that but Prism99 is right about getting the exercise to strengthen your abdomen and back and also while sewing get up and move a lot.