Iyanden Yellow vs Rotten Pus

How close are they?

ΔE 8.2, close: similar, with a visible difference side by side. Rotten Pus is more saturated than Iyanden Yellow.

Can I use Rotten Pus instead of Iyanden Yellow?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Rotten Pus is more saturated than Iyanden Yellow.

Can I use Iyanden Yellow instead of Rotten Pus?

The same difference applies the other way round: Iyanden Yellow 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.