Illustrator edits are significantly increasing file size

[Ryan 2535]

Hi,

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?

[Ryan 2535]

I should've clarified: I am looking to reduce exported PDF file size.

[Anna Lander]

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.

[Ryan 2535]

Thank you for this Anna. How do you do that?

[Monika Gause]

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.

[Ryan 2535]

Thanks Monika.

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.

[Monika Gause]

Don't use Illustrator for that purpose. Illustrator is not a general purpose PDF editor.

[Ton Frederiks]

Acrobat is better suited for editing page boxes like the bleed box.