Different basting sprays can cause the problem. Unnamed product in blue can is the worst, in my experience. I press the top after spray basting. Shoves any potential wrinkles to the outside and sets the spray. But...this weekend was finishing a wal hanging. Only spray in the house was the dregs if the dreaded blue can. Used it. Would have spent less time going to the store than the time spent in cleaning the gunk off the needle, bobbin case, hook race, etc.