Your ink coverage for any colour should no be more than an absolute maximum of 300%. This is really only a problem when shades of black are created from CMYK. For a rich black base we recommend using a value of C = 45% - Y = 0% M = 0% = K = 100%, This will give your black base a little shine as a simple 100%K can look a bit flat. You might also like to use for a slightly richer black C = 45% - Y = 20% M = 20% = K = 100%
CMYK stands for Cyan, Magenta, Yellow & Black.
I strongly recommend that black text if black is made up of only K=100%, this will ensure crisp sharp text.
To Clarify the following shows swatches of 100% each of the main CMYK colours.
!00% Cyan - 100% Magenta - 100% Yellow - 100% Black
Below is a mix of 100% K & 45% C, we call it Rich Black = 145% coverage
Below is a mix 100% Cyan, 100% Magenta, 100% Yellow & 100% Black. That's 400& ink coverage or density.
This would cause problems with the amount of ink saturating the paper making any white or light coloured text placed on top appear feathered where the ink has bled into it through being too heavy.
It appears to look like 100%k on screen but will cause problems, so for any black areas of print use Rich Black (100% K & 45% Cyan) (145% Coverage)