Wrack White vs J.A. Gray

How close are they?

ΔE 6.8, close: similar, with a visible difference side by side. J.A. Gray is more saturated than Wrack White.

Can I use J.A. Gray instead of Wrack White?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). J.A. Gray is more saturated than Wrack White.

Can I use Wrack White instead of J.A. Gray?

The same difference applies the other way round: Wrack White is 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.