While winding the warp for the last 16 placemats I noticed something. The spools of rug warp didn't exactly match! I had bought all twelve spools at one time and looking at them on the shelf they look like they match but they don't really. Thankfully it isn't terribly noticable in the placemats. You have to know and look hard to see the color difference. Here is a picture of a new warp I am winding for more placemats.
If you look closely you will see a darker color on the bottom third of warp. If you were to look at it from the other side of the room you might not even notice anything. The light has to be just right.