I can't figure out why some sections of font appear darker/thicker when I export to a .pdf

One other possibility is that the characters that appear artificially darker/thicker have been “outlined” or have both a fill color as well as a color outline applied to them.

Again, if you supply a PDF file, we can quickly advise as to what the symptoms point to.

          - Dov

Hi Jennifer.

I'd suggest you try one more thing before you get wrapped around the axle applying "fixes."

1) Open the offending PDF.

2) Zoom in to 200%, then 300%, then 400%. Be sure you can see samples of both the text that doesn't seem to be artificially thickened, as well as the text that does.

If you find, at a high display percentage, that the text no longer appears to be thickened, you've run across a long-running flaw of Acrobat displaying some documents.

On an infrequent, but consistent to a document basis on a given system, Acrobat's display will render with an artificial "thickening" of text characters. The reason I suggest zooming in to several different percentages is that the problem "clears up" at different percentages for different documents, on different systems.

If it's any consolation, if this is your problem it will invariably print fine. And if you have multiple systems in your shop, you'll often find that the display rendering is different on different systems -- or that the zoom percentage that "clears it up" will be.

I can't definitively say that this is your problem. I work on print-intent documents all day, every day, and I see this happen maybe every other month or so. But I run across this problem often enough that it's the first thing I check before I start trying to apply any fixes to a PDF with this issue. If your PDF is intended for print, I'd ignore it -- and just grumble to myself that WYSIWYG is once again one of those great lies like "the check is in the mail" while I output it. If it's intent is online or other digital display, I'd first check it on another machine (or two), and grumble a little louder to myself about it before I start messing with the PDF file.

Hi Jennifer,

do like Steve is suggesting.

But not only the PDF, also the InDesign document.

Zip both files and upload it to a service like Dropbox and post the downlod link.

In the meanwhile you could check the Pages panel and see if there is some transparency on the spread.
Might be something on the pasteboard as well.

Go to the panel options and enable the little checkerboard symbol that is showing that transparency is on the spread.

From my German InDesign:

Symbole

Transparenz (Transparency)

An object on the pasteboard with an effect applied: Transparency on the spread.

The symbol is showing up.

No transparency on the spread, the symbol is not showing:

Regards,
Uwe

Most likely, there is transparency involved, either explicitly or implicitly, in the areas where the darker/thicker text is seen and you are exporting PDF using a setting such as PDF/X-1a or PDF/X-3 that ruins transparency by flattening it as part of the PDF generation process. PDF versions less than 1.4 do not support live transparency and as such, the areas with transparency must be flattened into opaque objects. This may require that text objects be converted to vectors or raster bitmaps, both of which may have the possibility of having that darker/thicker look at lower magnifications.

A workaround is to make sure that the text is at the "top" of the design with no overprints or transparency. Better than that, export PDF using either PDF/X-4 or options based on at least PDF 1.4 (such as High Quality Print); don't use Press Quality!

          - Dov