So you can get an idea of how one color changes another, here is an exercise from the Josef Albers course THE INTERACTION OF COLOR. The two small squares are exactly the same color. The background color changes our perception of them. The one on the left seems darker than the one on the right and the one on the right also seems to have more of a yellow tint.
tomorrow...getting started in the attic.
Please pass this along to anyone you think might be interested.