I told them that their backing should be washed or not...according to the treatment that had been given to the fabrics used in the quilt top. Always to buy a good quality backing, keeping in mind that a high quality flat sheet is a horse of a different color all together. A high thread count flat sheet is not ideal for the longarm machine or the hand quilter. The very same thread count that feels luxurious as a sheet set can reek havoc when hand quilting and machine quilting because it is woven so tightly. I mentioned that when ordering fabric on line, for whatever purpose, that you should ALWAYS order at least a quarter of a yard more than you think you need. The picture below is one of an actual backing from a client...I had to trim about a quarter of a yard off of each end to square this sucker.
And, while we are on the subject..Let's just talk a little about squaring the backing. I polled some friends in the biz and the consensus was that they DO charge to square up a backing. *Anywhere from $10.00 per job to $45.00 and hour for prep work. It is SO EASY to square up. Just a royal pain in the rear end!!.. If you already have the tools to cut out your quilt top pieces you can square up your back. Now get OFF your back(side) and DO it (or see * above). Just fold it neatly, without any sags or pleats and having the selvage edges together. Fold it small enough to cut on the size cutting mat that you have and then DO IT!! Then remember to remeasure and make sure that it is still large enough for your quilt backing (4 inches larger on ALL sides). It really is just that simple...