Differences in colors in spot channels and layers

[treddie]

Hi again,

Was wondering why a spot channel appears completely different in color even though it has the same color as an equivalent CMYK color in a Photoshop layer?

[Crapaud]

The spot colour is outside of the cmyk gamut (or colour space). When you've converted the file to cmyk PS tries to get the closest match to the original, but it won't be the same as the colour doesn't exist in cmyk.

Explanation