Deep Scarlet Ink vs Ink Sepia

How close are they?

ΔE 28.6, loose: different enough that you should pick on purpose. Ink Sepia is a little lighter, much more muted, warmer than Deep Scarlet Ink.

Can I use Ink Sepia instead of Deep Scarlet Ink?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 29). Ink Sepia is a little lighter, much more muted, warmer than Deep Scarlet Ink.

Can I use Deep Scarlet Ink instead of Ink Sepia?

The same difference applies the other way round: Deep Scarlet Ink is a little darker, much more saturated, 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.