Tempest Blue Wash vs Umber Wash

How close are they?

ΔE 19.6, loose: different enough that you should pick on purpose. Umber Wash is a little lighter, warmer than Tempest Blue Wash.

Can I use Umber Wash instead of Tempest Blue Wash?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Umber Wash is a little lighter, warmer than Tempest Blue Wash.

Can I use Tempest Blue Wash instead of Umber Wash?

The same difference applies the other way round: Tempest Blue Wash is a little darker, cooler.

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.