I was doing some straight line quilting with my walking foot, and realized I was getting some "crud" on my work every so often.
I hope you appreciate my very technical jargon . . . crud is the word I used because I don't know exactly what this is:
Is it metal shavings from inside the walking foot? Is it solidified oil and dust from it? Or has a quilting gremlin left a little of his late night snack in there, and it's plopping out little by little?
Please help me out here -- I can't have these black marks all over my beautiful projects!!