Black is Black?
Well not exactly! The first kind of Black is single colour black which is 100% pure black process colour. Obvious? Well this is really best for small areas of, say, less than 25mm2 (text, logos etc) as more than this and you may get Set-off.
In terms of how we actually perceive colour black - like grey and white - is what is known as an achromatic colour: a colour lacking both hue and saturation. Although there has been much debate as to whether or not black is a colour at all, in design terms it's probably the most important colour of all.
On larger areas, single colour black can appear washed out and uneven. This is because the rollers on printing presses roll the ink off over large areas. The alternative is rich black which is made up of 100% Black and 40% Cyan. This should be used on large areas as the Cyan disguises any inconsistencies. However, rich black should not be used on small text as any tiny deviation in registration will give a blurred effect. Also be aware that the higher the percentage ink coverage, the longer the drying time required (particularly on uncoated stock).
Black will invariably appear duller on uncoated stock owing to the absorbency of the paper. This absorbency also means that any fine detail may disappear - try to avoid text of less than 8pt on uncoated stock.
Finally, be aware that placing an image with a black background onto a black area in Quark may reveal a difference between the two shades of black when printed. To get round this, take a sample of the image's black background with the Eyedropper Tool in Photoshop and take a note of the CMYK values which you then "mix" in Quark.