These panels are dry,showing the difference between cadmium red,and indian red.The panel on the left,cadmium red after reacting with lime,becomes more pink than true cadmium red pigment.Indian red pigment starts as a dark,earth tone red similar to terra cotta clay.After being painted onto lime plaster it turns into a lighter,violet tone.This color when mixed with white,can be used for flesh tones.It appears a true cadmium red in fresco would only be possible in secco.This means painting another layer of it over the dry color like these panels,to make it more vibrant again.One of the biggest limitations with fresco painting seems to be the restricted palette of colors and value scale possible with only the direct technique.