Understanding the "Color" White
From contributor D:
There are two main types of white pigments, with two different levels of opacity: titanium white and zinc white. Titanium white is much more opaque than zinc white. Zinc white is not a dye. It does not dissolve in solution; dyes do. But it also does not have the hiding power, the opacity, of titanium white (which also, like zinc white, does not dissolve). Dyes are transparent and pigments are not. Just the same, zinc white has a transparent quality to it, compared to the other white pigments available.
From contributor A:
Actually, the absence of all color is black. White is the presence of the full color spectrum. It is true that pigments are particulate in suspension and dyes are molecular in solution, but why no white solution?
Pigments are color absorbers. If a pigment appears to be blue, it is because all the colors in the spectrum of light hitting the object are absorbed except blue. For white, the pigment absorbs no color and what you see is the full spectrum of light that is hitting it - white or whatever color the light is. It's called subtractive color.
On the other hand, light adds color. If the spectrum of light that is hitting an object is changed, the object's apparent color will change because the light has shifted the spectrum that can be absorbed. This is why it is important to check color in the light source in which it will be displayed and why a touchup that looks perfect in one setting looks like ---- in another. It's also why a car appears to be a different color when parked under a halogen light at night.
Okay, so to get perfect white, you need a perfect non-absorbing pigment and a perfect white light. What's that got to do with dyes? Dye is like a mule; it isn't subtractive like pigment, and it isn't additive like light - it's kind of a tweener - it's both additive and subtractive. But you can't add anything to white and still have white, and you can't subtract anything from white and still have white, so how do you get a white dye? It's kinda like: you just can't breed mules. That's just the way it works.
From the original questioner:
Your posting was not only quite informative, but it also threw me for a loop. I don't see how white can be considered the presence of all colors. For the time being, let's forget about a white dye stain and concentrate on white.
If I take a dab of every color in my mixing booth and place it on a piece of clear plastic and then mix it up real good, I'm going to end up with a color that's closer to a black than a white. If on the other hand I take a dab of titanium or chalk white and mix those two together, I'm going to get something that looks like... well, a white. I'm not too old of a dog that I can't change my opinion on something.
From contributor Y:
When you mix all of the colors of visible light together, as in your computer's monitor or TV, then you get white. Mixing visible light is an additive process. Mixing colors with pigments or dyes is a subtractive process. The colorants absorb (subtract) certain colors from the visible white light and reflect the rest. When you mix a whole bunch of pigments together, they absorb (subtract) a whole lot of colors from the visible light spectrum, which doesn't leave a lot to reflect back, and thus you see black.
From contributor G:
If you spin a color wheel quickly enough, you will see white.
From contributor A:
If you mix the 3 primary colors correctly, you will get something approaching black, as you say. Why? Because you've now got a mixture containing 2 pigments that absorb all blue (red and yellow), 2 that absorb all red (blue and yellow), and 2 that absorb all yellow (red and blue). What's left? Nothing, as far as color is concerned. It's black - the absence of color.
Now let's try to mix those pigments (color absorbers) to get white. If any color is absorbed from white light, the color isn't white anymore. You just can't mix white from the primaries, as I'm sure you know very well - that's just the nature of color. To get white, you have to use a ground-up something (titanium or chalk) that doesn't absorb any color, but instead reflects all of the colored light that strikes it. So when you see white, you see the presence of all colors. But, you've had to put some non-color absorbing stuff on the surface to get it.
When you spin a color wheel fast enough, you see white. Why? Because you're seeing each of the colors in the wheel but at a speed that your eyes and brain can't keep up with, so you perceive the presence of all colors - white. But this is an additive phenomenon - not subtractive.
Dyes (solutions) are only partially absorptive or subtractive. If you remove all color from a solution, you get clear. I don't know of anything I can add to make it a white dye solution. (Yes, milk is a white solution, but I've never been able to get it to dye anything.)
I certainly don't mean to be a smart aleck, because I think you've asked a good question and deserve a good answer. Problem is that answer lies in the physics of light and color and isn't always intuitively obvious. Finishing is a fascinating art (with a little science thrown in), isn't it?
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