Hardened Leather vs Papyrus

How close are they?

ΔE 27.8, loose: different enough that you should pick on purpose. Papyrus is noticeably darker, much more muted, cooler than Hardened Leather.

Can I use Papyrus instead of Hardened Leather?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Papyrus is noticeably darker, much more muted, cooler than Hardened Leather.

Can I use Hardened Leather instead of Papyrus?

The same difference applies the other way round: Hardened Leather is noticeably lighter, much more saturated, warmer.

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.