You may be able to use a customer’s .ai file without Illustrator if it was saved with Create PDF Compatible File enabled. That option includes a PDF representation that other apps can read. Underbase, the Windows separation app from Automata Labs, opens PDF-compatible Illustrator files, rasterizes the vectors at 300 dpi, and prepares one plate per ink, a choked white underbase and true-size film. If the file lacks PDF compatibility, ask the customer to save it again with the option on, or to send a PDF.
This quick guide covers why some .ai files open and others do not, what to ask for, and how to check the artwork before making film.
Open PDF-compatible .ai artwork and prepare plates and film, without Illustrator.
Get it fromMicrosoft
Why can some .ai files be opened without Illustrator?
Adobe’s help page on saving artwork in Illustrator describes an option called Create PDF Compatible File. It saves a PDF representation of the document in the Illustrator file, and Adobe recommends it when you want the file to be compatible with other Adobe apps.
That embedded PDF is what a PDF-based importer reads. Without it, Underbase cannot rely on the .ai extension to provide usable PDF artwork. Older Illustrator formats and other importers may behave differently; a fresh PDF export is the dependable request when compatibility is uncertain. Renaming the extension does not create a missing PDF representation.
So the practical question is not “is it an .ai file?” but “was it saved PDF compatible?”
How do you tell whether a customer’s .ai file will work?
Try opening the file, then inspect what was imported.
- Open the file in Underbase. Drag it onto the window and check whether the artwork loads.
- Check the preview carefully. Look at small text, thin lines, placed images and gradients, and compare them with the customer’s reference. A preview is an intake check, not proof that every Illustrator feature survived.
- If it does not open, ask for a resave. Request Create PDF Compatible File or a PDF export. A damaged or otherwise unsupported file can also fail, so an import error alone does not prove the option was off.
Customers often do not know what this means, so give them a short message they can forward:
Please save the artwork from Illustrator with “Create PDF Compatible File” checked, or export it as a PDF, and send that file. Thanks.
Which file types are safest to ask for instead?
If you have a choice, you can ask for a format that does not depend on that option at all. Confirm the intended print size and review any missing fonts or placed artwork with the designer.
| File the customer sends | Opens without Illustrator? | Notes |
|---|---|---|
| .ai saved PDF compatible | Usually, yes | Underbase reads the PDF representation and rasterizes vectors at 300 dpi |
| .ai saved without PDF compatibility | Not through Underbase’s PDF import path | Ask for a resave or a PDF |
| Supported by Underbase | Check the imported preview against the customer’s reference | |
| SVG | Supported by Underbase | Check text, placed images and gradients after import |
| PNG or TIFF at print size | Supported by Underbase | Check resolution at the printed size |
| JPEG | Supported by Underbase | Soft edges may need index mode or cleanup |
For the resolution side of raster files, our guide to customer art resolution for screen printing explains what is enough.
What happens to the vectors when Underbase opens the file?
Underbase’s film pipeline uses rasterized plates. It rasterizes vectors at 300 dpi at their true size when opening a PDF or PDF-compatible AI file. For illustration, a 12 x 16 in design at that resolution becomes 3,600 x 4,800 pixels. Enlarging the resulting raster later does not recover vector detail, so check the intended print size and fine features in the preview.
From there, the separation works the same way as for other artwork:
- Inks you confirm. Underbase groups close shades and anti-aliased edges into inks and leaves the background fill unprinted. You rename, merge, reorder or switch off any ink before generating plates.
- White underbase with choke. For dark garments, the underbase is built from the inks you choose and pulled in by the millimetre to reduce exposed white at the edges. See white underbase for dark shirts.
- Plate budget. Tell Underbase how many screens your press has. It counts the underbase and every printing ink and holds generation when the job runs over. Use Merge inks to fit the budget, then review the result.
- Trapping. Spread or choke any plate, or trap every ink under the darkest in one click.
Review the inks, a choked underbase and one plate per ink before making film.
Get it fromMicrosoft
What should you check before you burn screens?
A file that opens is not automatically a file that prints well. Before you output film, check:
- Ink count. Vector logos often contain near duplicate colours, such as two slightly different reds. Merge them so you are not burning an extra screen.
- Background. Make sure a white or coloured background rectangle is not being treated as an ink.
- Thin lines and small text. Lines that are fine on screen can be too thin to hold on mesh. Zoom in on the preview.
- Size. Confirm the print size with the customer. Vector art scales, but your film should be true size.
- Print order. Review Underbase’s suggested order against the job. The white underbase and the highlight white are different printing roles; confirm which inks need white beneath them and which print on top.
The Output dots preview shows the raster plate at the selected output resolution. Inspect it before burning a screen, then verify physical film density, size and registration on your printer.
How do you get from the file to film?
- Open or drop the PDF-compatible .ai file, or the replacement PDF.
- Confirm the inks, the underbase and the plate budget in the live preview.
- Pick the film size, resolution and output folder.
- Generate. Film PDF, TIFF plates, channels, preview and a production ticket land in one job folder.
Film output includes a 1-bit film TIFF per plate at 600, 720, 1200 or 1440 dpi and a true-size film PDF on Letter to A2 or a custom sheet, with a mirror option for emulsion-down output. You can also print straight to a Windows printer. Film density depends on the printer, ink and media; an appropriate RIP or dense-black driver setting may be needed.
Underbase runs on your PC and makes no network connections, so customer artwork stays in the folders you choose. It is for limited-colour spot and index work, not a substitute for a dedicated photographic simulated-process separation workflow.
Frequently asked questions
Can I open an .ai file in a PDF viewer?
Sometimes, if it was saved PDF compatible, because the file then contains a PDF representation. Results vary by viewer, so the dependable route is to ask for a PDF.
Do I lose quality when the vectors are rasterized?
Underbase rasterizes at 300 dpi, which suits most garment prints at true size. Check fine detail in the preview before output.
What if the customer only has the .ai file and no designer?
If the file opens in Underbase, you can work from it. If it does not, someone with Illustrator needs to resave it. Ask whether the original designer can help.
Does Underbase need Photoshop or a plug-in?
No. It is a standalone Windows app with no plug-in and no subscription.
Try Underbase
Underbase is a one-time purchase with a free trial in the Microsoft Store; the listing shows the current price and system requirements. Open the next .ai file a customer sends and see whether it comes in cleanly before you ask for a resave. More detail is on the Underbase product page, and our guide on how to make colour separations for screen printing covers the separation steps.
Check compatible customer artwork and prepare a film pack locally, without Illustrator.
Get it fromMicrosoft