It's interesting you used a thrift shop bed sheet for the back and background as bed sheets use to be used all the time and now most people don't. I have been thinking of using them for backing. I didn't know how difficult it would be to quilt as I too am new to longarming. You didn't mention any problems using the sheet so that is encouraging. It is a really nice looking quilt and quilting looks great. You've given me a nudge to try the sheets on the back.