Has anyone besides myself wondered why there isn't a white dye stain? I know that white really isn't a color per se, and that it is the absence of all color… But hey, if we can put a monkey into space, why can't we come up with a white dye stain?
From contributor G:
Here ya go...
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.
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.
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.)
Another consideration: if I wanted to make a piece of cherry (almost) white, I would use a solution that removes all of the natural colors from the wood - then it will appear white. A 2 part bleach will come close, but that's not a dye.
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?