Martian Ironearth vs Chipping Medium

How close are they?

ΔE 67.6, poor: a clearly different colour, so not a substitute. Chipping Medium is noticeably lighter, much more muted than Martian Ironearth.

Can I use Chipping Medium instead of Martian Ironearth?

Not as a straight swap; see the closer alternatives below. Poor match (ΔE 68). Chipping Medium is noticeably lighter, much more muted than Martian Ironearth.

Can I use Martian Ironearth instead of Chipping Medium?

The same difference applies the other way round: Martian Ironearth is noticeably darker, much more saturated.

ΔE is the colour difference between our two swatch estimates: under 2 is a perfect match (you’d struggle to tell them apart), under 6 very close, under 10 close, under 15 fair, under 20 loose, under 30 very loose, and 30 or more a poor match. Real paints also differ in finish, coverage and how they thin, so test before you commit.