Warpfiend Grey vs Starship Grey

How close are they?

ΔE 15.7, loose: different enough that you should pick on purpose. Starship Grey is more muted, warmer than Warpfiend Grey.

Can I use Starship Grey instead of Warpfiend Grey?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Starship Grey is more muted, warmer than Warpfiend Grey.

Can I use Warpfiend Grey instead of Starship Grey?

The same difference applies the other way round: Warpfiend Grey is more saturated, 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.