Imp Yellow vs Yellow FS33531

How close are they?

ΔE 14.7, fair: the same colour family, but not a straight swap. Yellow FS33531 is a little darker, much more saturated than Imp Yellow.

Can I use Yellow FS33531 instead of Imp Yellow?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Yellow FS33531 is a little darker, much more saturated than Imp Yellow.

Can I use Imp Yellow instead of Yellow FS33531?

The same difference applies the other way round: Imp Yellow is a little lighter, much 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.