Blue Liner vs Dark Sea Blue

How close are they?

ΔE 8.6, close: similar, with a visible difference side by side. Dark Sea Blue is a little lighter, warmer than Blue Liner.

Can I use Dark Sea Blue instead of Blue Liner?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Dark Sea Blue is a little lighter, warmer than Blue Liner.

Can I use Blue Liner instead of Dark Sea Blue?

The same difference applies the other way round: Blue Liner is a little darker, cooler.

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.