Saving Illustrator files safely
As Mordy Golding in this excellent piece about Illustrator files pointed out, a native Illustrator file consists of actually two parts: a native AI part and a PDF, EPS or SVG part. This double strategy actually makes these files "native", that is: fully editable in the same version of Illustrator it's been created in.
When saving an AI file, you check the "PDF compatible" option to get the two-part file. For PDF and SVG you only get the two-part file when you check the "Illustrator editable" option. For EPS you don't have this choice.
For the rest of this article I'll assume that the option is checked and that you get the two-part file.
Opening the two-part file
Even with the two-part file there are still methods to completely ruin your file. So you not only need to know what Illustrator saves but also what's in that file and how Illustrator accesses saved content.
PDF, EPS and SVG when saved out of Illustrator usually contain mostly vector graphics. But of course huge parts of these graphics are not "live" anymore, that is: effects, brushes, multiple strokes or fills are flattened, expanded, maybe even converted into pixels. Also everything outside an artboard usually is not part of these parts of the file.
The exchange formats are needed to exchange files with other apps or place them into web pages. Also in AI files the PDF part is the one that InDesign or Photoshop access when you open an AI in them. But even Illustrator accesses the PDF part of its files from time to time. It happens when:
- the AI part got corrupt (mostly when saving directly to a server)
- you place an AI file into another AI file
- you open an AI file in a lower version of Illustrator
When this happens you'll notice, although Illustrator doesn't pop up a warning. Signs of opening a PDF are:
- the PDF import dialog
- clipping masks in the layer panel
- expanded effect, brushes and stuff
- and of course: there's nothing outside of the artboard
When you then make a change and just save the file, not only the PDF content gets overwritten, but also the original AI content gets replaced by the flattened PDF stuff, everything that was not on artboard, is definitely lost after saving the file.
What's the Difference between AI and PDF?
An AI file and a PDF basically contain the same: an AI part and a PDF part. The only difference is in the options you have when saving: when saving an AI, you can set option for that part (e.g. saving to a lower version). When saving a PDF you can save e.g. PDF/X, but you can't downsave to a lower AI version.
What about EPS versions?
When saving an EPS you don't have a choice whether there will be an AI file in it, but you can select the version of this included AI file.
Actually you don't select the EPS version, but the version of the included AI file. When you select a lower version there, of course flattening of effects or stuff will occur. So always keep a copy of the original file in the version you created it in.
Now what does this all mean for a secure workflow?
In order to work with a maximum of safety:
- Always make backup copies of your files.
- Always make an artboard for everything you want to keep (so that it gets into the PDF part of the file)
- When you want to open the file in an older version, downsave it to that version, but don't overwrite the original.
- When saving an EPS to version 10 (which is what most microstock agencies demand), always keep a copy of the file in your original version.
- When opening a file in a legacy version of Illustrator, never overwrite it when saving the file.
- When opening legacy files in a newer version, always save as, don't just save (I've outlined the details here).
- Don't directly save to networked or removable drives or USB sticks or the like.
Read my other tutorials
How to set up a file: vector/raster, color mode, resolution, file format
Mysterious things Illustrator does - Saving files (Video on Vimeo)
EPS – the zombie of file formats
Saving legacy files
Long Shadows with Illustrator
Creating a pentagonal pattern
Problems with align to pixel grid
Proposals for better better workflow in Illustrator
Freeform-artbrush with a gradient
Pathfinder doesn‘t react
Stylish guilloches with gradients
Outline object and outline stroke