Turquoise Siren vs Cobalt Teal

How close are they?

ΔE 8.6, close: similar, with a visible difference side by side. Cobalt Teal is a little lighter than Turquoise Siren.

Can I use Cobalt Teal instead of Turquoise Siren?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Cobalt Teal is a little lighter than Turquoise Siren.

Can I use Turquoise Siren instead of Cobalt Teal?

The same difference applies the other way round: Turquoise Siren is a little darker.

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.