Process inks are transparent: they colour the light that comes back from what they're printed on. On white paper that's what you want. On clear film, metallic foil board, kraft or a coloured stock, there is no white underneath, so the colours print dull, dark or see-through. A white underprint (also called a white underbase) puts a layer of opaque white ink down first, under the colours, so they look as they do on paper.
The White underprint card on the Tools tab of the 1-up editor makes that white plate for you, in the shape of the die. You choose how far it sits inside or outside the cut, and the page shows where the white will print before anything is applied.
When to use it#
- Clear labels and window clings: without white, the artwork is see-through and takes on the colour of whatever is behind it.
- Metallic stock and foil board: white under part of the design keeps those colours flat and opaque, while the areas without white keep the metallic shine.
- Kraft, coloured and dark stock: white under the colours stops the stock showing through and shifting them.
Printers that print white as a separate ink (most digital label presses, UV flatbeds and wide-format printers with a white channel) need it as a spot colour plate in the file. That's what this tool writes.
Turn it on#
- Make sure the page has a die (the cut line). The white follows it, so set it up on the Die & lines tab first (see The die).
- On the Tools tab, switch on Add a white underprint. The area where white will print appears on the page as a blue hatch with a dashed edge.
- Choose the Edge of the white, the Distance and the Corners (below). The hatch follows as you change them.
- Check the White ink name: the spot colour your press or RIP prints white from. White is the default; Opaque White, Underbase and W1 are offered, and you can type any other name.
- Press Apply to print-ready file in the Output section. Until then the card shows Not applied yet.
- Edge of the white
- Inset (choke) pulls the white in from the cut, so none can show at the edge if the cut lands slightly off. Outset (spread) makes the white wider than the cut: use it when the white should reach the edge with room to spare, or when you want a visible white border. A distance of 0 follows the cut exactly.
- Distance
- How far the white sits inside or outside the cut, up to 0.5 in (12.7 mm). The default is a 0.25 mm inset.
- Corners
- Round rounds the corners of the white where it is moved; Sharp keeps them pointed, like a square-cut label.
- White ink name
- The name of the white spot colour in the file. Use the name your RIP or press expects for its white channel.
Windows and holes in the die stay free of white, and move with the same inset or outset.
Inset or outset?#
An inset is the usual choice for labels and stickers that are cut after printing. A die cutter or a print-and-cut device always has some tolerance; a small inset means that if the cut wanders, the edge shows the colours or the clear film, never a thin line of white. A quarter to half a millimetre is a common starting point; ask your finisher what their cutter holds.
Use an outset when the white must cover the whole piece even if the cut wanders, for example under a full-bleed background on clear film, or when you want a white keyline around a cling.
How it's written into the file#
The white is a solid fill in its own spot colour, on its own layer named White, over the page's artwork. It is set to overprint, so it adds the white plate without knocking anything out of the colour plates: on press, the white prints first and the colours print on top of it. It is drawn so that viewers that don't show overprint still display the artwork unchanged; open the Separations tab to see the White plate on its own (see Separations).
The white is added after the bleed and before a die you made in the editor, so the bleed never covers it and the die line stays on top. Changing any white setting marks the print-ready file Out of date until you apply again (see Bleed and the print-ready file). Imposition places the print-ready file, so the White layer goes onto the imposed sheets with the rest of the artwork.
Files that declare PDF/X-1a or PDF/X-3 allow neither layers nor this way of drawing: the white is still written as an overprinting plate, and a warning says that viewers without overprint preview show it over the artwork.
In 3D proofs and trapping#
Because its name reads as white, the plate is recognised as a white ink: in 3D proofs it shows as opaque white under the colours on clear or metallic materials, and trapping lays it down first and pulls it back under the colours with its underprint choke (see Trapping settings and inks).