Yesterday we saw how the yellow of the yolk fades quickly. I think it's still fading, becoming whiter! Later this evening I'll paint up another white chip for a three day comparison. I think I've read that fading does occur over a few days--wish I could find that reference.
Gretchen asked if I compensate for the inevitable whitening of egg yolk yellow. At this time, I haven't tried. I think this will only become clear when I can accurately mix a Munsell neutral and then see if it holds. Granted, in white the yellow is obvious. As the value decreases, will the yellow be as prominent? How about when I begin introducing color? I think only by experience will I be able to answer these questions. (Note: The Munsell kit call for using acrylics for these exercises. I decided to use egg tempera to challenge myself and become more familiar with my medium. Also note: the rational painting recommendation below for burnt umber is based on oils.)
Although it doesn't present properly, the Munsell chip is actually a darker value than my first painted chip. You see, the Munsell chip is N9/, a value of 9. Munsell values theoretically go to 10. Titanium white can present as high as 9.75 and I am certainly seeing a lot brighter white than that N9/ chip. I forgot all about this and somehow associated pure titanium white with N9/. What this means is that I must tone down the pure white for the true value of 9.
On my lower set of chips above, the chip on the left is the bluish hue I was trying to neutralize. That's the Munsell chip in the middle. On the right is my mix with burnt umber, the bottom part of that chip with slightly more umber than the top. See how it's pulling in closer in hue? The value still needs work, though.
I found this method on rational painting.org where Graydon Parrish recommends mixing the proper value using black and white and doing the same with burnt umber and white. Then with both mixes at the same value, mix them to achieve an exact neutral. The thought is that one must deal with only one property (hue, value, chroma) at a time.
So you can see that I have some work ahead of me. And yet, I've already learned a lot and starting to pick up an eye for real neutrals. I'll be working on my neutrals while forging ahead on the remaining exercises in Chapter 1.