Sickly Skin vs Natural Flesh

How close are they?

ΔE 17.1, loose: different enough that you should pick on purpose. Natural Flesh is a little darker, more saturated, warmer than Sickly Skin.

Can I use Natural Flesh instead of Sickly Skin?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Natural Flesh is a little darker, more saturated, warmer than Sickly Skin.

Can I use Sickly Skin instead of Natural Flesh?

The same difference applies the other way round: Sickly Skin is a little lighter, more muted, cooler.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.