burlap is jute right? which has a MOE of around 20-30 Gpa, but burlap is a fabric, and linen isn't nearly as stiff as flax fibers for some reason, at least according to the data I've seen. So, if you really wanted to shift the plane toward the back, and reduce the tension those knots feel, maybe you should get straight up jute fiber, or go for a stiffer fabric like linen (since flax has a MOE of around 40-50 Gpa), Or apply more of it. The discrepency between flax and linen fabric really has my head scratching. (40-50 for flax but like 9 for linen?) I think I need to study more sources for linen fabric. Maybe what they were using wasn't pure linen.