Last week we had one day where a few rugs came in with pile reversal.
Pile reversal is the areas of the rug where the fibers go in the opposite direction as the rest of the rug causing a dark/light spot.
I say dark/light because it depends on where you are when you look at the rug. The spot will change from light to dark when you walk around the rug.

Pile reversal can happen any where on a rug and is permanent.
Here is an article about pile reversal in carpet that is a pretty interesting read.
I love the theory about electromagnetic forces as being a cause for pile reversal.
It can be difficult to photograph pile reversal where the fibers are a bit higher and fluffier than the rest of the rug.

This type of pile reversal is when the knots of the rug are knotted in a different direction to the rest of the rug.
It is really hard to see on the back of the rug, but the knots are slightly different.

What is interesting is that the knot change isn't in a straight line. It is very uneven and only in a small area on the side of the rug.
The rug is hiding a secret.
When you see a dark area on your area rug it may not be a spill or dirt, it maybe the mysterious pile reversal.
Thanks for reading, RugloverMary