ΔE 14.9, fair: the same colour family, but not a straight swap. Ion Blue is a little darker, more saturated than Wrack White.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Ion Blue is a little darker, more saturated than Wrack White.
The same difference applies the other way round: Wrack White is a little lighter, 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.
See Wrack White on the colour wheel See Ion Blue on the colour wheel
All matches: Wrack White equivalents · Ion Blue equivalents