Iron Wolf vs N3 Neutral Gray

How close are they?

ΔE 15.3, loose: different enough that you should pick on purpose. N3 Neutral Gray is a little darker, more muted than Iron Wolf.

Can I use N3 Neutral Gray instead of Iron Wolf?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). N3 Neutral Gray is a little darker, more muted than Iron Wolf.

Can I use Iron Wolf instead of N3 Neutral Gray?

The same difference applies the other way round: Iron Wolf is a little lighter, more saturated.

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.