The model forgot to use the lotion and wants me to fix their ashy knees. I searched Google and the forum here but came up empty handed. Any suggestions? This has to be a common problem!
You might try to cut and paste a patch of her skin with same tones, like the leg. Feather edges, adjust opacity, and blend in.
Color blending mode will work well here. Just select a color from near the knee, paint over the ashy bits on a separate layer with a plain soft brush and set that layer's blending mode to color.
Thanks guys! I couldn't make Curt's suggestion work but am having some success with J's. Much appreciated.