Hidden in the innards of the Sturdy node group is the 11 stops ColorRamp that powers the shader’s color expression. You don’t have to worry about that, though, because there is an easier way to micromanage the compounding shades if you wish: the Sturdy+ node group, with its customizable color stops.

And that’s the third way of controlling color expression with the Sturdy shaders: just plug the Sturdy+ node group instead of the standard one and you’re good to go. Choose your own colors to compound the full range of tonal expression, from the highlights on the top to the darker shades on the bottom.