You can expect color variations in grasscloth (and other natural material) wallcoverings. These products are made from authentic natural elements, like grass and reeds and hemp and other such materials.
Because each individual blade of grass absorbs dye differently, and because different fields of grass, or even different handfulls grabbed by the worker women, are of differing thicknesses and porosities and thus take the dye differently, there will be differences in the color of these reeds as they are sewn onto their paper backing.
So, you often (usually) end up with an effect we call “paneling” or “shading,” which are differences in color between strips of wallpaper (see third photo), or even within the same strip – such as being darker at the top but becoming lighter at a lower point on the wall.
To minimize this, many manufacturers are labeling their material in the sequence that it came out of the factory. The idea is that, if the strips are hung in the order they came off the dye machine, the strips that are the most similar in color will be next to each other on the walls.
The problem with this particular job is – the vendor didn’t send bolts that came in any sort of correct sequence at all. See second photo.
Luckily, this room is chopped up enough that I can plot the layout so that on most walls, only strips off the same bolt, or closely within the same sequence, will be touching each other.
Unfortunately, even strips within the same sequence can fall prey to paneling. In the last photo, the narrow strip on the far right is from sequence 14-9. The two strips to the left of it are from bolt 14-10. And the two strips to the left of those (next to the door frame) are from bolt 14-11.
As you can see, 14-9 and 14-10 are very close in color / shade. But there is a big difference between the shades in 14-10 and 14-11.
Note that this is not considered a defect or error. These color variations are considered part of the “inherent beauty of these natural materials.”