This happened to me on the first bigger project I ran on my own - the client sent a file with a logo set in some nice, narrow font, and on the test print the letters were thicker, wider, simply different. I didn't figure out what was going on right away. It turned out that the computer we opened the file on didn't have that font installed, and the graphics program's system quietly substituted a replacement. No error message, no red exclamation mark. Just a different font, and that was it.
That is exactly what happens when a PDF does not have embedded fonts. And although the topic sounds like a technical detail for prepress geeks, in practice it ruins a great many projects - especially where typography is part of the brand identity, not just „some text“.
Why a font can change at all
A PDF does not inherently contain fonts - it is a file that describes the appearance of a page. If the description says „use the Montserrat Bold font“, and the program reading that PDF does not have Montserrat installed, it has to improvise. Most often it substitutes the most similar system font, or, in a worse scenario, replaces everything with Arial or Times New Roman. That looks different, has different letter proportions, different character spacing - so the whole text shifts, breaks in different places, and sometimes simply no longer fits in the box it was supposed to fit into.
Important: this is not the printer's fault. It is a question of whether the file we received carries everything it needs to look the same on every computer in the world. PDF can do that - but it has to be allowed to during export.
Embedding fonts - what it actually means
Font embedding means saving, inside the PDF file itself, the data describing the letterforms used in the project. In other words: the PDF stops saying „use font X“ and starts saying „here is font X itself, use it“. There is no need to have it installed on the computer opening the file - everything is inside.
Most layout programs - InDesign, Illustrator, QuarkXPress - do this automatically when exporting to PDF, as long as the export settings are correct and the font itself has a license that permits embedding (some fonts, especially free ones from questionable sources, have license restrictions that block embedding - and that can be a source of further problems).
How to check a file before sending it: Checking whether fonts are embedded takes literally a few seconds: open the PDF in Acrobat, go to Document Properties → Fonts tab. Next to each font there should be „Embedded Subset“ or „Embedded“. If you see just the font name without that note - you have a problem.
Outlines, or converting text to curves - the other way to get there
There is another approach: instead of embedding the font, you can convert the entire text into vector objects - Bezier curves that describe the shape of each letter the same way they describe the shape of a logo or an illustration. In Illustrator that's „Create Outlines“, in CorelDRAW „Convert to Curves“, in InDesign you have to do it via export or additional plugins, because InDesign is not natively eager to do this.
After such an operation, the text technically stops being text. It can no longer be edited, selected with the cursor, or have typos fixed without going back to the source file. But in exchange it looks identical always and everywhere, because it doesn't depend on any font - it's simply a shape, just like any other graphic element.
This is a radical but very reliable solution. It is used mainly for logos, visual identity elements, sometimes for die-cutting files, or for jobs where the file travels between different companies and there's no certainty who will be opening it or on what equipment.
Embedding or outlines - which to choose
There is no single right answer, because it depends on what stage the file is at and what will happen to it next. If you're sending a finished, final PDF for print and no one is going to change anything in it anymore - outlines give an absolute guarantee that the look won't change, either on our end or at any point along the way. But if the file may still need minor text corrections (and with catalogs or brochures this sometimes happens even at the last minute), outlines are inconvenient - because every typo requires going back to the source files.
In practice, a compromise usually works best: work on source files with embedded fonts, and apply outlines selectively - for logos, for elements that must remain untouched, or for a file that is genuinely the final version and is going into production.
A small real-life example
A company is preparing a brochure in InDesign. The designer uses a font bought from one of the type foundries, paid, with a full commercial license. When exporting to PDF, they forget to check the embedding option (or, as sometimes happens, the program silently embeds not the whole font but only a fragment of it - a subset, only the characters actually used in the document). The file arrives at the prepress stage. Opened on a different computer, without that font, it gets a system substitute. The whole brochure falls apart, paragraphs break in different places, the heading no longer fits in its designated space. The correction goes back to the client, the file has to be generated again - and that's a loss of time that, on jobs with a specific deadline, simply isn't in abundant supply.
A font subset is not the same as the full font: Font subsetting - that is, embedding only the characters actually used - can be a trap during later edits. If someone adds new text in the PDF containing a character that wasn't in the original document (e.g. a special character), that character won't display correctly, because its description simply wasn't saved in the file.
The most common mistakes we see
The first and most common: exporting with default settings, where font embedding is disabled or limited to a subset without checking whether that's enough. The second: files from Word saved as PDF via a virtual printer, where Word doesn't think about embedding in a print-oriented way at all - sometimes it works, sometimes it doesn't, depending on the version and system settings. The third, a very classic one: someone applies outlines to only part of the text, forgetting about headings or text in tables, and the result is patchy - some letters look right, and some change.
A fourth, less obvious mistake: a font that looks fine on screen because the system substituted a visually similar replacement, but the font name in the file's metadata was kept from the original. That means the file looks fine while browsing, but during actual processing for print, on a different workstation, the real problem shows up. That's why „it looks fine on my screen“ is no proof at all that the file has been prepared correctly.
How to do it right - step by step
In InDesign, when exporting to PDF, choose Adobe PDF (Print), and in the Compatibility tab it's best to set PDF/X-1a or PDF/X-4 - these standards, by definition, require all fonts to be embedded; without that the file won't pass validation. This is, incidentally, one of the reasons why PDF/X is so well liked in prepress: the standard's own mechanism catches this error before the file ever reaches the press.
In Illustrator, when exporting, it's worth checking the „Embed Fonts“ option (the name may vary depending on the version), and if the project is a logo or something that needs to stay untouchable - simply do Create Outlines on a copy of the file, keeping the original with live text for further editing.
In CorelDRAW the situation is similar - Convert to Curves on a copy, and when exporting to PDF, check the font-related options in the export window, because Corel tends to be rather unclear in its naming there.
Word is the hardest case, because it's a writing program, not a layout program, and it thinks about print typography in its own way. If you absolutely have to use Word, it's worth checking the TrueType font embedding option in the PDF save settings (there is such an option in the document save settings), and ideally verifying the finished file in Acrobat before sending it as well.
Before you send a file for print, check
- Whether Acrobat shows „Embedded“ or „Embedded Subset“ next to every font
- Whether the logo and key graphic elements have been converted to curves (outlines)
- Whether the export from InDesign/Illustrator was done with the PDF/X standard, not the default screen setting
- Whether the font used in the project has a license that allows embedding
- Whether a file from Word has actually been verified after saving, and not just „looks fine on screen“
And if the file has already reached prepress without embedded fonts
This is not a hopeless situation, just a loss of time. As standard practice in such cases we ask the client for a corrected file, because only someone with access to the source files and the original installed fonts can fix this in a way that won't change the layout. Substituting a replacement font at the prepress stage is an emergency, visually risky solution - the very same mechanism that caused the problem may try to „fix“ it, but with no guarantee that the result will match the original intent of the design.
Image resolution in files for offset and digital printing is standardly 300 dpi at 1:1 scale - fonts are a different category of problem than raster graphics, but the principle is the same: the file has to carry everything needed for correct printing, instead of relying on something being „patched up“ along the way.
File format matters
The preferred format at the prepress stage is a print-ready PDF, ideally finalized as PDF/X-1a, or a properly prepared composite PDF. For select applications we also accept TIFF or JPG, but that's more for purely raster materials, not for documents with live text. The reason PDF/X-1a is so recommended in the context of fonts is simple: this standard simply won't let you generate a file without embedded fonts. If validation fails, the program will tell you - so the error comes to light before the file reaches anyone, rather than only at the proofing stage.
Not every typographic mistake comes from bad intentions or carelessness. Sometimes it's just a program's default setting that nobody changed, because nobody knew they had to. But now that you know where to click and what to look for in the Document Properties window - you no longer have an excuse.
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Ask us before you send the file
If you're not sure whether your file has been prepared correctly, it's simpler to ask before sending it into production than to find out about the problem after the proof print. We respond to quote requests within a maximum of 24 hours, on business days between 9:00 AM and 5:00 PM - and we're happy to take a look at your file even before the production stage.