How do I set up a white ink underbase for custom clear labels?

Why do CMYK colors look translucent on clear film without white ink?

On a normal desktop or commercial press printing on white paper, the paper itself supplies 100% of the white brightness in your design. There is no white cartridge in standard four-color CMYK printing: when you leave an area white on your screen, the press simply lays down 0% ink and lets the paper show through. When you switch the material from white paper to transparent custom clear labels, any area with 0% ink becomes completely see-through, and any CMYK color printed directly on the clear film lets 40% to 70% of the background light pass right through it. By laying down a dedicated 5th ink channel of high-opacity titanium-white ink on the clear film milliseconds before the CMYK and Pantone colors are printed on top, we create a precision white canvas exclusively underneath your graphics. Everywhere else on the label stays crystal clear.

1. Pure white text & monograms: printed with 100% opaque white ink and zero CMYK on top.
2. Solid opaque CMYK & Pantone colors: printed on top of a matching 100% opaque white ink underbase.
3. Translucent stained-glass tint zones: printed with CMYK ink directly on the clear film (0% white ink underneath).
4. 100% transparent background & windows: left completely unprinted (0% white ink and 0% CMYK).

How do I build a White_Ink spot-color layer in Adobe Illustrator?

If you are building your own print-ready vector file in Adobe Illustrator, Affinity Designer or InDesign, never color your white ink areas with standard CMYK white (C=0, M=0, Y=0, K=0), because RIP software reads 0% CMYK as 'print nothing at all.' Instead, represent white ink using a dedicated Spot Color swatch on its own layer so the press knows exactly where to fire the white printhead. Follow these five steps to build a clean White_Ink channel in less than three minutes, or skip straight to uploading your artwork and let our prepress team build the channel for you at no charge.

1. Step 1 · Create a new Spot Color swatch: open the Swatches panel, click New Swatch, name it exactly White_Ink, set Color Type to Spot Color, and set the preview color to 100% Cyan (or 100% Magenta) so you can see it clearly on screen.
2. Step 2 · Create a layer named White_Ink: place it directly above or below your CMYK Artwork layer, and keep your CutLine layer at the very top.
3. Step 3 · Duplicate opaque elements onto White_Ink: copy all logos, text, barcode boxes and illustrations that need to be solid white or opaque color, paste in place (Cmd/Ctrl+F) on the White_Ink layer, and fill them with the White_Ink spot swatch.
4. Step 4 · Choke underbase edges by 0.25 pt (0.0035 in): on colored elements that have white ink underneath, inset the White_Ink shape by −0.25 pt so a tiny hairline of white never peeks out from under the color.
5. Step 5 · Turn on Overprint Fill & Stroke: select everything on the White_Ink layer, open the Attributes panel (Window > Attributes), and check Overprint Fill and Overprint Stroke.

What are the prepress specs for white ink, choke and barcodes on clear labels?

Use the reference table below to verify your clear label file before exporting a PDF/X-4 or Adobe Illustrator file. Every specification here is designed to keep small ingredient text razor-sharp and ensure retail barcode scanners read your UPC code on the first pass. If you are also adding metallic gold or silver accents, you can combine a White_Ink layer with a Foil_Stamp spot layer on the same label, or compare full metallic stocks on our custom foil labels page.

Why do you choke the white underbase by 0.25 pt under colored logos?

When a press prints white ink first and CMYK colors second on a moving web of clear film, even a microscopic registration shift of two thousandths of an inch could allow a sliver of the white underbase to peek out along one side of a dark green, navy or burgundy logo. In prepress, we prevent that by applying a 0.25 pt (roughly 0.0035 inch) choke, shrinking the white underbase path inward by a fraction of a hair underneath colored objects. Notice that you only choke the white underbase when another color sits directly on top of it. For elements that are meant to appear pure white (such as white ingredient text, white borders or a white logo), keep the White_Ink shape at 100% full size with zero choke. And for retail barcodes on custom bottle labels and custom jar labels, always place a solid 100% White_Ink rectangle extending at least ⅛ inch outside the left and right quiet zones of the black barcode bars.

What if I do not know how to set up a spot white ink channel?

You never have to touch spot channels or choke settings if you do not want to. More than three-quarters of brands ordering custom clear labels from CubitPack simply upload their normal PDF, AI, PSD or high-resolution PNG file in Step 3 of the quote form and write a quick note like 'Back all logos and text with white ink, leave background clear.' Our prepress specialists build the White_Ink spot channel, apply the 0.25 pt underbase choke under colored graphics, add a solid white backing box behind your barcode, and send you a clear two-part digital proof plus a 3D container mockup before you pay. On the proof, we show both the finished realistic view and a magenta/cyan mask view so you can confirm every square millimeter of white ink.

What are the most common white ink setup mistakes on clear labels?

Our prepress check catches these automatically on every order, but if you build your own files, watch out for these five white-ink traps

1. Coloring white text with 0% CMYK (paper white) instead of a Spot Color swatch, which tells the press to leave those letters unprinted and transparent.
2. Forgetting to check Overprint Fill on the White_Ink spot layer, which causes the white layer to knock out the CMYK colors sitting on top of it.
3. Applying a −0.25 pt choke to standalone thin white text instead of only choking the white underbase beneath colored shapes.
4. Leaving the area behind a black UPC barcode transparent, making the barcode unreadable against dark liquids or amber glass.
5. Using a soft raster drop shadow over a clear background without deciding whether the shadow should fade to white or fade to clear.

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