Thunder Storm vs Steel Grey

How close are they?

ΔE 10.8, fair: the same colour family, but not a straight swap. Steel Grey is noticeably lighter, cooler than Thunder Storm.

Can I use Steel Grey instead of Thunder Storm?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Steel Grey is noticeably lighter, cooler than Thunder Storm.

Can I use Thunder Storm instead of Steel Grey?

The same difference applies the other way round: Thunder Storm is noticeably 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.