Illustrator gradient turns grey when saved as pdf
I'm working on a project where I want to add a gradient over the bottom of a picture so it fades to the background. However, when I save the file to PDF, the gradient gets a grey color, not the black I selected. When I save as PNG, it doesn't change the color.
Should I change something in my settings somewhere? I've tried different PDF-viewers, but every viewer shows the same weird grey color.
Also, while we're at it, why does the gradient desaturate the image?
You most probably used a 'poor' black as the black in the gradient: 100% black ink, but no C, M or Y.
The K ink is not black by any means: it's dark grey at best, and doesn't stand scrutiny when printed on a large area. To get a good, saturated black, you'd better use a 'rich' black: 100%K with some percentages of other inks added. You can influence the 'character' of the black with these colours: the added colours shine through the black, giving a very cold black with 100%C, 100%K, or a warm and red black with 60%C 40%M 100%K. Be sure not to exceed the maximum ink percentage of ~280%.
To use a 'rich' black in a work, it's best to make it a swatch, so you use the same black all the time. Makes it easier to include it in a gradient, too.
Do not use a rich black for text. Alignment between printing plates is always imperfect, yielding colour sheens at the borders of the letterforms, severely hindering legibility. to say nothing of sharpness.