About warp defects (human mistake)

Basically, put each organization in one of the reeds.

There are exceptions, for example, in plain weave, sometimes one thread is inserted instead of two threads in the reed feather.
The difference is that the threads are evenly aligned when one thread is inserted than when two threads are inserted into the reed.
Since the space ratio is reduced by that amount, the yarn may be squeezed by the reed and weaving may not be possible.

It is not recommended to put more than one thread in the reed feather in plain weave.
For example, if three threads are inserted into the reed feather in a plain weave, streaks will appear in the vertical direction.

Basically, the warp threads are put into the heald in order.
１→２→３→４→１→２→３→４→・・・
For example, when a plurality of threads are broken, a mistake may be made as shown in the left figure when re-threading the threads.
The fabric has streaks in the vertical direction.

The state where you put it in the wrong place when you pass it through the reed.
Normally, three threads, three threads, three threads, etc. are threaded.
However, in the figure on the left, four threads, two threads, three threads, etc. are mistakenly threaded.