What artwork specification do printed cans need?
Supply vector artwork built to the supplier's dieline, in CMYK, with fonts outlined and images at 300 dpi or better at final size. The two things that catch most first-time buyers are that the printable band is smaller than the can looks, and that bare aluminium is not white, so anything that needs to read as a solid colour sits on a printed white base layer.
Most artwork rejections are not design problems. They are geometry problems, and they are all avoidable if you know the shape you are designing for.
You are designing for a cylinder, not a rectangle
Artwork is supplied flat and wrapped onto the can, so the left and right edges of your file meet. Anything that crosses that seam has to line up, which means a repeating pattern needs to tile cleanly and a wordmark should not sit across the join.
The can also narrows at the top. Artwork near the shoulder compresses as the metal necks in, so type and fine detail placed high on the can will distort. Keep anything that has to stay exact inside the straight-walled section.
The base and the dome are not printable. Neither is a narrow band at the neck. The printable area is always smaller than the can, and by more than people expect the first time they see a dieline.
What to supply
| Item | What printers generally expect |
|---|---|
| File format | Vector PDF, AI or EPS built on the supplier's dieline. Flattened image files are accepted for photographic work but limit what can be adjusted |
| Colour space | CMYK, with any brand colours listed by reference alongside so the printer knows what is being aimed at |
| Images | 300 dpi or better at final printed size, not scaled up from screen resolution |
| Type | Outlined or with fonts supplied. Small reversed-out text is the first thing to break, so check the minimum point size for your press |
| Layers | White base layer separated and named, so it can be adjusted independently of the colour |
| Barcode | Supplied as vector, not as an image, and positioned in the straight-walled section |
The white layer is a real part of the design
Aluminium is reflective and slightly grey. Ink printed straight onto it takes on that base, so colours read darker and cooler than they do on paper.
Where you want a colour to look like itself, the press lays down white first and prints on top of that. Where you want the metal to show through, it does not. That is a design decision, not a technical default, and it is one of the few things a can can do that a paper label cannot.
Decide deliberately which parts of the can are metal and which are white-backed, and mark it on the file. If you leave it to the printer you will get their judgement, not yours.
Barcodes and legal copy
Orient the barcode so the bars run vertically, parallel to the can's axis. Bars that run around the circumference get compressed by the curve and scan badly.
Keep the quiet zone clear on both sides and avoid placing the code over a busy background or close to the seam. Ask the supplier to confirm the minimum bar width they can hold.
Mandatory copy competes for the same space. Ingredients, allergens, volume, ABV where it applies, producer address, deposit-return marks and recycling marks all have to fit, and in more than one language in some markets. Lay these out before the design, not after it, because they are the part you cannot shrink.
Proofs
A PDF proof confirms content and position. It tells you almost nothing about colour, because a backlit screen and an ink film on metal are different objects.
Ask for a printed proof on the actual can before a full run, particularly on a first order or any time the artwork carries a brand colour. Sign off on metal, in daylight, with the over-varnish applied. The varnish shifts the finish slightly, so a proof without it is not the finished article.
The short version
Get the dieline first, design inside it, keep the important things off the shoulder and off the seam, decide where the metal shows, and approve colour on a real can. Everything else is ordinary print production.
Common questions
What file format should can artwork be supplied in?
Vector PDF, AI or EPS built on the supplier's dieline, in CMYK, with fonts outlined and any placed images at 300 dpi or better at final size. Ask for the dieline before you start designing rather than adapting a label file afterwards.
Why does my can artwork need a white layer?
Aluminium is reflective and slightly grey, so ink printed directly onto it reads darker and cooler. A printed white base layer restores the colour. Leaving the white out is a valid choice where you want the metal to show through, but it should be a deliberate one and marked on the file.
Can artwork print all the way to the top and bottom of a can?
No. The base and dome are not printable and a narrow band at the neck is left clear, so the printable area is smaller than the can appears. The shoulder also compresses artwork as the can necks in, so keep type and fine detail in the straight-walled section.
How should a barcode be placed on a can?
Supply it as vector, position it in the straight-walled section away from the seam, and orient it so the bars run vertically rather than around the circumference. Keep the quiet zones clear and confirm the minimum bar width the press can hold.
Do I need a physical proof before printing cans?
For a first order or any artwork carrying a brand colour, yes. A PDF proof confirms layout but not colour. Approve a printed can with the over-varnish applied, viewed in daylight, before committing to the run.
Keep reading
What is the difference between digital and offset can printing?What is short run can printing?What drives the cost of a printed can?How do order minimums for printed cans actually work?Can you match a Pantone colour on a printed can?How do you get custom printed cans made?How do you get printed cans made in Ireland?How long does it take to get printed cans?What Swaay does