REFERENCE > USING DASHES
There seems to be much confusion among novice typesetters and writers about the proper use of dashes. Most problems are of a grammatical nature, but there are also typographical problems, with some typesetters not knowing how to set a dash, and imitating them by typing two consecutive hyphens.
Unless you are using an old typewriter (or typesetting HTML documents), you should never need to simulate a dash again. Any professional font is equipped with en dash and em dash characters. Mac users can achieve these characters by typing opt-hyphen and shift-opt-hyphen respectively, while PC users type ALT-0150 and ALT-0151. Unfortunately, these characters are currently unavailable for use on the web.
In his book Rules of Printed English (Darton, Longman & Todd), Herbert Rees warns writers about overusing dashes, and says that the dash "is often, like the excessive use of italic, a substitute for clarity of thought". If you are going to use dashes, here is some information about using them properly:
WHAT ARE THEY?
In the words of Robert Bringhurst:
"Type is normally measured in picas and points, but horizontal spacing is measured in ems, and the em is a sliding measure. One em is a distance equal to the type size. In 6 point type, an em is 6 points; in 12 pt type it is 12 points, and in 60 pt type it is 60 points. Thus a one-em space is proportionately the same in any size... Half an em is called an en.
An em dash, therefore, will be equal in length to the point size that you are setting the type in, and an en dash will be half as long."
THE PARENTHETICAL DASH
The most common use of the dash is as a replacement for parentheses (i.e. brackets). The current standard is to use en dashes surrounded by single spaces:
A more traditional standard, and one which is still found in many style manuals, is to set the same text with em dashes that are NOT surrounded by spaces:
As font designers often apply very little spacing around the dashes, you may find that additional space around the dashes will make them look more pleasing. You can add a little tracking before and after the em dashes, but don't add a full space.
MORE COMMON USES OF EN-DASHES
En dashes should be used instead of hyphens when you are expressing durations of time, or a difference in distances, ages, etc.:
En dashes are also used to indicate ranges:
The following examples show both en-dashes and hyphens used in the same sentences:
The en-dash should NOT be used when followed by the word "from":
OTHER USES OF DASHES
A dash can be used to indicate an interruption or change of thought in a sentence. In the following example, an em dash should be used in preference to an en dash, to make the breaks in thought more obvious:
A dash can be used as a more pronounced pause than a comma:
An em dash can be used to before the final phrase of a sentence to sum up the main idea of the sentence:
A dash can be used to prolong a letter that describes a sound, such as a growl. An en dash is sufficient for this, but notice the em dash which follows the growl below:
Dashes can also be used to indicate a missing word or part of a word, or the abrupt ending of a sentence in mid-thought:
Robert Bringhurst points out that the em dash can be used "to introduce speakers in narrative dialogue. The em dash, followed by a thin space (M/5) or word space, is the normal European method of marking dialogue, and it is much less fussy than quotation marks:
Hopefully these examples will be useful in helping you to use dashes properly, because a world with fewer typesetting flaws is a better world indeed.
©1998 Lloyd Springer
- Typographic, Vol. 4, No. 1 (1973) includes an article about dashes, reprinted from Monotype Newsletter 88, published by The Monotype Corporation Limited.
- The Elements of Typographic Style Robert Bringhurst. Published by Hartley & Marks