ΔE 14.5, fair: the same colour family, but not a straight swap. Steel Blue is a little darker, cooler than Seraphon Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Steel Blue is a little darker, cooler than Seraphon Blue.
The same difference applies the other way round: Seraphon Blue is a little lighter, 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.
See Seraphon Blue on the colour wheel See Steel Blue on the colour wheel
All matches: Seraphon Blue equivalents · Steel Blue equivalents