I work for a print shop and much of my work revolves around resizing, removing, and adding bleed on pdfs sent to me from clients.
Where I get baffled is that many times a file comes to me at one size, and from a simple edit like removing bleed (simply changing artboard size from 3.75x2.25 to 3.5x2) the file size increases unpredictably.
Most recently, I had a banner come to me from a client as a pdf at 23MB, I removed the bleed by simply resizing the artboard and saving a copy as a pdf (Preset: "High Quality Print"), and the file exported was 71MB.
I have some clients send me their high quality print files at low sizes like 420KB, and I very rarely seem to be able to create files that small.
What is likely occurring? How can I reduce file sizes without loss?
I should've clarified: I am looking to reduce exported PDF file size.
Do the files contain raster images? If yes, the effect may be caused by the difference of compression settings between client's and your file saving. I would try to check the Effective PPI of the raster images and set the same one in the PDF saving settings.
Thank you for this Anna. How do you do that?
You get PDFs from clients and edit them in Illustrator? Those PDFs have been created in Illutrator and saved with "Illustrator editing capabilities"?
Because if not, it would be a better solution to use dedicated prepress software that is meant for editing PDFs. Editing them in Illustrator might ruin them thoroughly. The file size would be your smallest problem then.
Yes, it's the software our shop uses. For most, it's relatively simple: changing Artboard size to create a proof minus the bleed, or using document setup to add a bleed box and then manipulating elements to create bleed.
However, no matter how simple the change, I see a large difference in file size once it passes through Illustrator.
Don't use Illustrator for that purpose. Illustrator is not a general purpose PDF editor.
Acrobat is better suited for editing page boxes like the bleed box.