How to prevent a light band in a dark gradient

[David31335732h5xj]

Novice user here. In all Adobe programs (InDesign, Photoshop, and Illustrator) I am getting the same problem when trying to create a gradient. I want to go from dark purple to solid black. The issue is that any gradient to black goes through a light grey color first. Is there  a way to avoid this? To make the purple progressively darker until it becomes black? 

[Ton Frederiks]

Try adding some purple to the black.

[Brad @ Roaring Mouse · Accepted solution]

This is most common when you are trying to create a gradient between two CMYK colors, two spot colors, or between a  spot color and a CMYK color; you will always get a "dip" in the centre, because remember, at the halfway point it's a mix of half of what your end colors are.

Say your Purple is 60C 100M 0Y 0K  and your Black is 0C 0M 0Y 100K. A gradient between these two would have 30C 50M 0Y 50K at the halfway mark, which looks greyish.

As suggested by Ton, you could use a rich black if you are working in CMYK. In my example, you can see how adding the purple mix to the Black  end retains a rich center as there's no longer a "dip" in the purple. THis can be problematic in a CMYK workflow as you don't want to get too much more than 300% or so ink coverage at the Black end, Fortunately 60+100+0+100 comes to 260% so you'd be fine.

However, in RGB, the "dip" doesn't happen, because you are working with light and not ink.

 

 

 

 

[David31335732h5xj]

Thanks so much, that's interesting and helpful.