You ofcourse note there are no neutrals or black shown on this wheel. Mixtures of other colors that do appear on the wheel make up a variety of neutrals.DID YOU KNOW that complimentary colors ( ones across from each other on the wheel) mixed together make a brownish neutral? eg... red and green ( ala Christmas colors are across from each other on a color wheel. Look what happens when they are mixed together. Same is true mixing blue and orange) What I'm showing here was done with approximately equal parts of textile ink.
When this equal parts idea gets translated to thread... think of it as same value thread in the complimentary color. This may seem hokey.. but as we will learn, it's pretty powerful knowledge to have when starting to choose thread colors. Might one think if you wanted to tone down a fabric area on your quilt top... you might consider using a complimentary color of thread in pretty much the same value... i.e on red fabric.. use same value green thread... and vice versa.