Brass vs Castellax Bronze

How close are they?

ΔE 18.1, loose: different enough that you should pick on purpose. Castellax Bronze is noticeably darker, more saturated, warmer than Brass.

Can I use Castellax Bronze instead of Brass?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Castellax Bronze is noticeably darker, more saturated, warmer than Brass.

Can I use Brass instead of Castellax Bronze?

The same difference applies the other way round: Brass is noticeably lighter, more muted, 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.