Originally Posted by kaelynangelfoot

I had that happen, it turned out it was the spray starch I was using. The residue built up on the iron and burnt, leaving brown marks on my white fabric. Now I check my iron periodically and wipe off the residue with a damp cloth while the iron is cool. I haven't yet found a spray starch that doesn't leave it. I put the damaged block on the back of the quilt and used it as a label.