Yes, if you swoop too fast you'll get eyelashes or loops on the back. I never used poly batting so can't help you there. But keep practicing. I took a class from Patsy Thompson on feathers and I have to admit my feathers are looking pretty darn good!! And I bet I've used about 40 little practice sandwiches - get muslin on sale at Joann's and use leftover batting pieces. Practice does make perfect :) Marlene