Could I be wrong? Sure. But someone please explain to me why Seurat's Dots produce one outcome, and Newton's Disc (supposedly) another. Both used PIGMENT colors not individually perceivable to the eye - yet they (supposedly) got different results. So what's going on??
Seurat's Dots were doomed to failure from the outset. The reason is that they are colors of pigments, rather than colors of light. Another reason is that in order for the painted result to appear as expected, resulting colors do in a spinning disc, they simply MUST be placed side-by-side, and NOT on top of one another.
However, even with pigments, a spinning disc of the 3 basic colors of light, Red, Green, and Blue can be made to function to create White, by the additive behavior of color, provided several conditions are met.
Those conditions are as follows:
First, the light source under which such a disc is viewed should be an intense, nearly full-spectrum light source, rather than just some incandescent lightbulb burning in the corner of your living room, or studio.
Second, the pigment colors that you select to be representative of "Red", "Green", and "Blue" as sections of the disc need to be as pure, and as "scientific" (realizing that some artists on this site dislike it when I use the term, "scientific") as possible. In other words, one cannot not merely grab some color that is labeled "Red" on its tube, and expect it to function as well as true, scientific Red, for this purpose. It must be true, RED, and as close to the Red spoke of the color wheel as possible, as well as being as near the outer ring as possible, as well.
The same criterion goes for the Green, and Blue colors on this wheel, as well.
This sort of selection of Red, Green, and Blue is not easy when dealing with pigments, but it is absolutely necessary if you wish your spinning disc to actually appear as "White", or "near-White" when viewed under a full-spectrum illumination.
I can guarantee that such a wheel, composed of pigments, will truly work to the extent that when spun, the Red, Green, and Blue sections of the spinning disc will actually appear White. And, when the Blue section is covered with Black, it will appear Yellow. When the Green section is covered with Black the color will appear to be Magenta, and when the Red section is covered with Black, the color will be Cyan.
I know this works, because I have seen such a spinning disc, made of Red, Green, and Blue pigments, and the results were as should be expected.
The problem with Seurat's approach is that he was not using pure Red, Green, and Blue pigments--instead, probably just grabbing any ol' paint labelled "Red", "Green", or "Blue" for his true, Red, Green, Blue primary colors of light, as well as piling some on top of each other rather than carefully placing them side-by-side. Such a sketchy approach surely won't function well, and will undoubtedly yield such grayed colors as were forthcoming in his paintings.
It is nice to experiment with the "basics of color" in a painting, but when you do, it is also imperative that you understand the true science of the behavior of color, and what real colors are required to achieve the expected results.
Using any ol' Red, any ol' Green, and any ol' Blue simply won't cut it, and Seurat seems to have done just that.
He seems to have latched onto one, basic principle of color, but failed to have gained the knowledge of several other ones that may have led to a bit better results.
For what it may be worth, the RGB spinning disc that I witnessed that was so extraordinarily successful in creating White, as well as Cyan, Magenta, and Yellow was made up of colored poster board for which the demonstrator had shopped for an enormously long time. He had gone through lots of trial-and-error attempts with various colors, and finally had settled on some colors that were (if I recall correctly) in the form of what they called, "Day-Glo" colors--extremely pure, and bright. This spinning disc was a real jaw-dropper, and it turned many skeptics into believers of the true behavior of color, once viewed by them.
Oh, .....and just a a helpful bit of insight regarding this spinning disc of additive, Red, Green, and Blue colors, the true Red is a color that MOST artists would call "Orange".