Incursion Orange vs Sun Yellow

How close are they?

ΔE 8.8, close: similar, with a visible difference side by side. Sun Yellow is a little lighter, more muted than Incursion Orange.

Can I use Sun Yellow instead of Incursion Orange?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Sun Yellow is a little lighter, more muted than Incursion Orange.

Can I use Incursion Orange instead of Sun Yellow?

The same difference applies the other way round: Incursion Orange is a little darker, 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.