Simple shifts in skin colour can be achieved using the 'Col' chip in the HSV settings found on the Skin tab.

You should choose a colour which is almost, but not quite white, as even a small change in the Col chip makes a very noticeable change in the skin colour. You may also need to very slightly increase the 'Value' parameter too to compensate for the darkening of the colour that occurs when you use anything other than white in the Col chip.

Note that once you have found some satisfactory vales for tanning the skin then you can save them as a preset for later use.

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