I can't imagine telling a customer that I didn't prewash batiks! The only reason I can think of is that the shop doesn't want to deal with the lengthy bleeding of these fabrics, which sometimes require washing several times before the color running stops. I've had astonishing amounts of dye run out of even small pieces of batik. Sometimes I've even have to throw them out rather than risk ruining other pieces in the quilt or even the entire quilt.