Tiamat Orange vs Light Orange

How close are they?

ΔE 9.3, close: similar, with a visible difference side by side. Light Orange is more saturated than Tiamat Orange.

Can I use Light Orange instead of Tiamat Orange?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Light Orange is more saturated than Tiamat Orange.

Can I use Tiamat Orange instead of Light Orange?

The same difference applies the other way round: Tiamat Orange is 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.