Majestic Fortress vs Light Turquois (Phthalo)

How close are they?

ΔE 12.4, fair: the same colour family, but not a straight swap. Light Turquois (Phthalo) is a little lighter, cooler than Majestic Fortress.

Can I use Light Turquois (Phthalo) instead of Majestic Fortress?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Light Turquois (Phthalo) is a little lighter, cooler than Majestic Fortress.

Can I use Majestic Fortress instead of Light Turquois (Phthalo)?

The same difference applies the other way round: Majestic Fortress is a little darker, warmer.

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.