For the Carlotta-Egyptian gown I needed 12 yards lame in a rich raspberry. I dyed made samples of a few fabrics settling on a white/gold silk dupioni. Unfortunately by the time I went back to the store to buy the fabric they no longer had 12 yards, so I found what I thought was the same fabric at another store (Same appearance, same fiber content, price)...as you can see not so much. Fabric A (on the left) was woven with the same threads all through the warp, fabric B (on the right) varied what metallic threads they used, probably for economy. The threads then reacted differently to heat during the dye process resulting in stripes. I LOVE stripes!
I honestly think this is "accidental design" at it's finest.