I would recommend 100%K alone so you don't need to worry about registration. If you want a rich or warm black, I would use a Pantone spot colour (my swatch books are in storage so I cannot recommend an actual #).

On a coated paper I use 60/47/45/100 looks really black.
When I need to put white text on a black background I make two layers in indesign:
1) 60/47/45/0 with white letters with 0.35 pt white outline around them.
2) 100% black overprinted with the same white letters without any outline.

30/20/20/X is the way to go..

Sorry, I forgot to mention my suggestion is for offset printing on coated paper. I usually use this method for book covers and if I need small texts on black in a catalog.
Would be too dark for an offset paper like Munken.

You might want to discuss it with your printer to get their recommendations.

Dear Kristians, small texts on black is exactly what I need (in a 10fold accordion brochure on 115gr coated paper)!
Unfortunately, no Munken or any other Artic Paper available in many italian areas (the "kingdom" of Fedrigoni Group and of anonymous coated papers).

A trick I've used in four colour printing to cope with misregistration is mixing 100% of one ink with x% yellow. On a side note: Is there any point in ink traps for reversed text? Aren't you trying to stop the ink from bleeding in the opposite direction.

There's a printer in Sweden that knows a lot about these things: Fälth & Hassler.

If you’re knocking out small text from a 4-color black, then the exact composition of your rich black will not be the issue, registration will. Check with your Pre-press to see if they can spread the type in the CMY plate (I think some pre-press software provides this level of control).

Kristians and kentlew are talking about trapping. It's a good idea if you aren't closely working with the printer. It gives you a rich black for color purposes, but a one-color black for the reversed type.

Also keep in mind that if this is really small type, you're going to want to slightly beef up the type (via a thin stroke or consider going with a bold weight).

On the other hand, if you are close to the printer in terms of being able to work directly with them, this may very well be something that they'd prefer to handle themselves. Traditionally, this was a pre-press/on-press issue that was handles by the professionals that handle the actual printing. In this era of really cheap printing, those craftsman aren't as abundant as they once were.

Many skilled print shops may also have their own preferred rich black that they'd like you to use that takes into account all sorts of variables (the paper, their presses, their presspeople, etc.)

@JamesM
You might want to discuss it with your printer to get their recommendations.

@aluminum
Many skilled print shops may also have their own preferred rich black that they'd like you to use that takes into account all sorts of variables (the paper, their presses, their presspeople, etc.)

Sage advice from both: don't try to second-guess the people who are actually going to do the work. Believe it or not, printers actually appreciate being consulted on technical issues.

> Traditionally, this was a pre-press/on-press issue
> that was handles by the professionals that handle
> the actual printing.

Yes, when working with a good-quality print shop, take advantage of their expertise. Their prepress people deal with trapping (and related issues) on a daily basis and know what works best on their equipment.