Can someone help me punctuate this sentence?

Here's the sentence:

Based on your experience which type of paint do you suggest we use glossy or matte?

I was thinking that it should be punctuated like this:

Based on your experience, which type of paint do you suggest we use–glossy or matte?

But that looks totally wrong to me. Can anyone help me figure out the correct way to write this?

  • Whatever you end up with (and you have a fair query – this happens commonly in conversation) there will be some who object. I wouldn't use a comma (too lightweight) after ' ...we use' though I probably wouldn't have marked it wrong as a teacher (of science at the time). An ellipsis is another possibility, but probably over-dramatises. I'd say the dash (I prefer the spaced en-dash, but that's another controversy) is just about right (colons being so dated), though some might plump for question mark and new sentence fragment (with a second question mark). Commented Jan 12, 2021 at 19:55
  • Although this would not solve the punctuation for that particular phrasing, you could just break this into two sentences, with something like: You have experience with different types of paint. Do you suggest we use the glossy type or the matte type?
    – Noah
    Commented Jan 13, 2021 at 0:09

1 Answer 1


The most common and most traditional is arguably this:

Based on your experience, which type of paint do you suggest we use: glossy or matte?

In principle, the colon could be replaced by a comma or even a dash, but I am going to argue that the colon works best here.


The comma before which

The comma preceding which is not controversial; see the many results here.

The supplement glossy or matte

Also not controversial is that glossy or matte is a supplement, i.e. a part of the sentence that is not integrated into the syntactic structure of the clause, but is instead semantically linked to an anchor. In this case, the supplement has a form of an appendage. In general, supplements that are appendages should be either put into parentheses, or else preceded with one of the following punctuation marks: a comma, a colon, or an appropriate form of a dash. American usage prefers an em-dash without spaces around it, while

in British usage, an en dash (with space before and after) is usually preferred to the em dash as punctuation in running text, a practice that is followed by some non-British publications as well. (The Chicago Manual of Style (17th ed.), 6.83).

According to CGEL (p. 1350),

In speech, supplements are marked as such by the prosody: they are intonationally separate fromthe rest of the sentence.

The comma is the 'lightest' separator, so it will correspond to the shortest prosodic break in speech.

Parentheses not appropriate

It is non-controversial that in your case, using the parentheses would not be appropriate.

Em-dash disfavored

I would say that the em-dash would normally be disfavored here. According to The Chicago Manual of Style (CMoS),

Em dashes are used to set off an amplifying or explanatory element and in that sense can function as an alternative to parentheses, commas, or a colon—especially when an abrupt break in thought is called for.

Note that introducing a list of items is not specifically named in CMoS as one of the functions of the em-dash. In your case, glossy or matte is more like a list of items.

Where CMoS does mention em-dashes is with expressions introduced by that is, namely, for example, and the like:

There are simple alternatives to the stigmatized plastic shopping bag—namely, reusable cloth bags and foldable carts.

Best bet: the colon

On the other hand, CMoS says the following about the colon:

A colon introduces an element or a series of elements illustrating or amplifying what has preceded the colon.

Grammarbook says this:

Use the colon after a complete sentence to introduce a list of items when introductory words such as namely, for example, or that is do not apply or are not appropriate.


You may be required to bring many items: sleeping bags, pans, and warm clothing.

A colon usually does not precede a list unless it follows a complete sentence.

Note that, in your case, what precedes the appendage is indeed a complete sentence: Based on your experience, which type of paint do you suggest we use?

The comma: a possibility

Finally, let's discuss the possibility of a comma.

I looked through all the uses of comma described in CMoS, and the closest ones are those where they separate descriptive phrases (e.g. That was John, with a hat all crooked), possibly with introductory phrases like such as and including.

Having said that, to my ear, using a comma to introduce glossy or matte introduces a level of lightness, of informality (which would explain why CMoS, a very academic style manual, would not recommend it for this purpose). In speech, it would correspond to a shorter prosodic pause than the colon. This effect might be appropriate, depending on what you are trying to accomplish with this sentence, and of course depending on the context.

  • I couldn't find even a style guide recommendation, so I didn't post an 'answer'. Commented Jan 12, 2021 at 19:59
  • 1
    @EdwinAshworth I am so sure this is 'right' (i.e. most common, most traditional), I posted the bare answer before finding the justification for it. I'm looking for one as we speak. But if I don't find it, I'll remove the answer. Commented Jan 12, 2021 at 20:02
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    Yes; perhaps it's one special application where the colon still holds sway. Though if you're my age, it could just be that we both have long memories and have seen examples many years ago. Commented Jan 12, 2021 at 20:05
  • @EdwinAshworth OK, see what you think… Commented Jan 12, 2021 at 22:12
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    Meaty, certainly, and sound advice. The examples given don't include any where the matrix sentence is interrogative. I've done my best with such where the 'residue' is not a list of alternative answers (and where I think I've seen the odd colon, but think it hugely dated / inappropriate) at Where to put the question mark for a sentence which starts with a question but doesn't end with one: <Can you book a room in advanceØ because otherwise we'd be in troubleØ> Commented Jan 13, 2021 at 12:55

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