Grey Seer vs Aged Bone

How close are they?

ΔE 16.8, loose: different enough that you should pick on purpose. Aged Bone is a little lighter, more saturated than Grey Seer.

Can I use Aged Bone instead of Grey Seer?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Aged Bone is a little lighter, more saturated than Grey Seer.

Can I use Grey Seer instead of Aged Bone?

The same difference applies the other way round: Grey Seer is a little darker, more muted.

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.