If a PDF has layers, each layer can become its own PDF file. The layers have to be in the file already: Acrobat and the free Acrobat Reader list them in the Layers panel. Illustrator cannot do the split for you. When it opens a layered PDF, it puts everything on a single layer.
We tested this on two real files: a label with five layers that we built for the test, and one sheet from a public set of construction drawings with 43 AutoCAD layers. This is what came out of each.
What counts as a layer in a PDF
A PDF layer (the PDF standard calls it an optional content group) is a named group of artwork that a viewer can switch on and off. Packaging files use layers for print, white ink, varnish and die lines. AutoCAD and other CAD programs can export one PDF layer per drawing layer. This quick check in Acrobat tells you whether your file has any.
Test 1: a label with five layers
The label is 90 x 60 mm with rounded corners on a 100 x 70 mm page. It has five layers: Print for the artwork, White for the white underprint, Varnish for a spot varnish on the round logo, Die cut for the cut line, and Info for the job slug. White, Varnish and the cut line use the spot colors White, Varnish and CutContour.
The result:
- Five PDF files, one per layer, each named after its layer.
- Every file keeps the full 100 x 70 mm page, so the layers stay in register when you put them back together.
- The spot colors keep their names. White, Varnish and CutContour are still spot colors in the split files, not converted to CMYK.
- We stacked the five files in their original order and compared them with the original at 150 dpi. No pixel differed by more than 2 of 255 levels, which is edge smoothing.
Test 2: an AutoCAD sheet with 43 layers
The second file is one 42 x 30 inch sheet from a public set of construction drawings. It has 24,635 paths on 43 CAD layers and one more layer that holds 4 images.
- 44 PDF files, one per layer name.
- The PDF stored six CAD layers in two separate blocks each, among them A-WALL and Existing. Both parts of each went into the same file, so every name appears once.
- Layers that draw nothing, such as Levels and References, were left out.
- Together the 44 files hold 24,635 paths, the same number as the original sheet, and every file is still 42 x 30 inches.
- The split took 15 seconds on our test machine.
More on this case, including when to ask for the DWG instead: AutoCAD PDF to Illustrator with the layers intact.
What you get besides the layer files
The split files are ordinary PDFs, so you can open any of them on its own. The package also includes an Illustrator script. Run it from File > Scripts and it builds one Illustrator document with a named layer for each file. For the other ways to get PDF layers into Illustrator, see how to extract layers from a PDF.
When a PDF cannot be split
The split only works on layers that are in the file. A PDF saved without layers, or with its layers merged on export, has nothing to split. A layer that is switched off by default is still in the file, and it is split out like the others.
If the check finds no layers and you have the source file, export the PDF again with layers switched on: in InDesign tick Create Acrobat Layers, in Illustrator tick Create Acrobat Layers from Top-Level Layers, and in AutoCAD tick Include layer information in the PDF options.
Try it on your own file
Upload the PDF to the free check. It lists every layer it finds and shows a preview you can switch layer by layer, before you pay anything. The price depends on the file: the label above comes to $5 and the construction sheet to $12.
Questions
Does splitting change the artwork?
No. In our label test the five files, stacked in their original order, matched the original at 150 dpi, and the spot color names stayed the same.
What happens to a layer that is switched off?
A layer that is off by default is still in the PDF, so it is split into its own file like the others. Illustrator leaves such a layer out when it opens the PDF.
What if my PDF has no layers?
Then there is nothing to split. Export the PDF again from the source file with layers switched on, or ask the sender for a layered export.
Do I need Illustrator?
No. The layer files are ordinary PDFs. Illustrator is only needed if you want the included script to rebuild them as one layered Illustrator document.