IJN Green Nakajima vs Deep Green

How close are they?

ΔE 8.0, close: similar, with a visible difference side by side. Deep Green is a little lighter than IJN Green Nakajima.

Can I use Deep Green instead of IJN Green Nakajima?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Deep Green is a little lighter than IJN Green Nakajima.

Can I use IJN Green Nakajima instead of Deep Green?

The same difference applies the other way round: IJN Green Nakajima is a little darker.

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.