White balance problems are often considered purity defects. In fact, this problem is related to areas of different colors on the screen. While purity defects are due to incorrect alignment, poor white balance is the result of a difference in brightness of one of the RGB colors. Practically speaking, if you display a blue window on screen and some parts seem darker or lighter than others, the fault is in white balance. This type of defect is due to small differences in the shape or quality of some of the phosphor dots. It is actually very difficult to apply a perfectly regular layer of phosphor to a screen.
There are two types of moiré patterns. The first and most common is found on shadow mask monitors. The way they are manufactured can create wave effects on screen, caused by dark and bright dots. This is an effect produced by differences in brightness between adjacent dots. The more precise the beams of a monitor, the more it will be prone to moiré. Adjusting the precision solves these problems, even if this means lowering it to find the best solution.
Example of the moiré effect
The second type is the video moiré. This affects both shadow mask and aperture grill monitors, and produces a checkered effect made up of bright and dark dots. This is due to a slight lack of regularity in the refresh rate of each beam, as well as to distribution differences in the phosphor layer on the screen.