Naples Yellow Deep vs Flat Yellow

How close are they?

ΔE 11.6, fair: the same colour family, but not a straight swap. Flat Yellow is a little lighter, cooler than Naples Yellow Deep.

Can I use Flat Yellow instead of Naples Yellow Deep?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Flat Yellow is a little lighter, cooler than Naples Yellow Deep.

Can I use Naples Yellow Deep instead of Flat Yellow?

The same difference applies the other way round: Naples Yellow Deep is a little darker, warmer.

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.