How to Prepare Your Artwork for Foil Stamping

Why Foil File Prep Is Different

Foil stamping is a physical process — a heated metal die pressing real metallic foil onto paper under pressure. That means your digital file has to translate cleanly into a physical tool. The rules are different from standard CMYK printing, and the mistakes are less forgiving. A misaligned gradient in CMYK might look slightly off. A misaligned element in foil means remaking a brass die and reprinting the entire run.

This guide covers everything you need to set up your files correctly the first time: file format, layer structure, foil separation, line weights, trapping, typography, and the common mistakes that cause production problems. If you follow these rules, your foil job will proof cleanly, produce beautifully, and avoid costly reprints.

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Every minimum for every process, on one page: minimum line weight and type size.

One note before we start: Print Peppermint includes a free digital proof with every order. Our team reviews your files before production and will flag any issues. But the closer your files are to production-ready when you submit them, the faster you'll get to proof approval and into production.

The Golden Rule: Foil Is a Separate Layer

This is the most important concept in the entire guide. Everything else follows from it:

Foil is not ink. It's not a color in your CMYK build. It's a completely separate physical process that requires a separate physical die. Your file must have foil elements on their own dedicated layer, completely isolated from your CMYK artwork.

Think of it this way: your printer needs to produce two separate things from your file. First, the CMYK print plates (for any full-color printed elements — photos, backgrounds, colored text). Second, the foil die (for any metallic elements). These are manufactured independently and applied to the paper in separate press passes. If your foil elements are mixed into your CMYK layers, the prepress team has to manually separate them — which costs time, introduces error potential, and delays your proof.

How to structure your file

Set up your document in Adobe Illustrator or InDesign with clearly named layers. At minimum you need: a "CMYK" layer (or "Print") containing all full-color elements, and a "FOIL" layer containing only the elements that will be stamped in foil. If you have foil on both front and back, use separate layers: "FOIL — Front" and "FOIL — Back." If you're using multiple foil colors (gold AND silver, for example), each color gets its own layer: "FOIL — Gold" and "FOIL — Silver."

On the foil layer, set all elements to 100% black (K: 100, C/M/Y: 0). The color doesn't matter for production — it's just a mask showing the die maker where foil goes. But 100% black is the universal convention because it's clean and unambiguous. Don't use spot colors, don't use rich black (C:40 M:40 Y:40 K:100), don't use gray. Pure K:100.

If you want to be extra clear, create a spot color swatch called "FOIL" or "Gold Foil" and apply it to all foil elements. This makes the intent unmistakable in the file. But 100% black on a clearly labeled layer works just as well.

File Format and Technical Requirements

Accepted file formats: Adobe Illustrator (.ai), EPS (.eps), or PDF (.pdf) with outlined fonts and embedded images. Illustrator native files are preferred because layers are preserved exactly as you built them. PDFs work but make sure layers are exported intact (File > Save As > PDF, check "Create Acrobat Layers from Top-Level Layers"). EPS files flatten layers — submit the .ai alongside the .eps if possible.

All fonts must be outlined (converted to paths). No exceptions. Foil dies are cut from vector paths. If a font isn't outlined, the die maker's system may substitute a default font, and your proof will come back wrong. In Illustrator: select all text, Type > Create Outlines. Verify by switching to Outline view (Cmd+Y) — all text should appear as paths, not highlighted text boxes.

All images must be embedded, not linked. If your CMYK artwork contains placed images (photos, textures), embed them in the file. Linked images that don't travel with the file cause missing image errors in prepress.

Document setup

• Color mode: CMYK (the document itself should be CMYK even though foil elements are a separate process)
• Resolution for raster elements: 300 DPI minimum (though foil elements should be vector — raster only applies to CMYK printed elements like photos)
• Bleed: 0.125" (3mm) on all sides — this applies to BOTH the CMYK artwork and the foil layer. If your foil extends to the edge of the card, it needs to extend into the bleed area too.
• Card size: set your artboard to the final trim size plus bleed (standard US business card: 3.75" × 2.25" with bleed, or 3.5" × 2" trim)

What NOT to submit

Canva exports, PNG/JPG files, Word documents, PowerPoint files, Photoshop files (for the foil layer — raster foil masks are problematic), or any file with live text. These cause delays and often need to be completely rebuilt.

Minimum line weights and type sizes for foil

Fine detail survives foil. Foil holds positive lines down to 0.1 mm (0.28 pt). We design to 0.15 mm (0.43 pt, 0.006 in) or thicker for the crispest strike, with gaps at 0.25 mm (0.71 pt); the gap floor is 0.15 mm. Raised foil and raised spot UV use 0.3 mm (0.85 pt, 0.012 in) line and gap targets, with a 0.17 mm floor. Type remains 7 pt positive, 10 pt reversed and 12 pt for high-contrast serifs.

Foil releases from its carrier where the heated die touches the sheet, then shears along the artwork’s edges. A positive line down to 0.1 mm holds; 0.15 mm gives the crispest strike. Gaps have their own 0.25 mm target and 0.15 mm floor. Measure both at final size without changing the mark’s character.

High-contrast serifs carry hairlines much narrower than their stems. Keep the existing 12 pt foil minimum and measure the smallest detail against the 0.1 mm floor, targeting 0.15 mm. Foil and letterpress share this positive-line guidance; preserve the chosen lettering.

Fine lines and detailed marks can stay in foil. Measure the supplied artwork at final size against the 0.1 mm line and 0.15 mm gap floors. Our team preserves its character and discusses only local below-floor corrections. See foil combinations.

The honest truth: We review every file before production and will flag any elements that are below our minimum thresholds. But if you catch these issues before submitting, you avoid a revision round and get to production faster.

Knockout vs Overprint — The Most Common Mistake

This is the most frequent file preparation error we see — and the most confusing for designers who haven't done foil before.

The question: When a foil element sits on top of a CMYK-printed background, should the CMYK layer have a hole (knockout) where the foil goes, or should the foil stamp directly on top of the printed ink (overprint)?

The answer depends on the foil color and the background:

• Opaque metallic foils (gold, silver, copper, rose gold) on any background: KNOCKOUT. Punch a hole in the CMYK layer where the foil will go. The foil stamps directly onto bare paper, not on top of ink. Metallic foils achieve their best reflectivity when bonded directly to the paper surface.
• Light or transparent foils on a dark background: KNOCKOUT is even more critical. A white or clear foil on a dark CMYK background will look muddy if the dark ink is underneath.
• Foil on an unprinted area (bare paper): No knockout needed. There's nothing to knock out — the CMYK layer has no artwork in that area.
• The exception — registered emboss with foil: The foil mask and the emboss mask must align exactly. Submit both as separate layers from the same file, with elements in precisely the same position. Even 0.5mm of misregistration is visible.

Trapping

Foil never goes over ink. When a foil element sits in a CMYK background, knock the ink out with a 1mm designed gap around the foil — foil registers to print within ±0.5mm, so a deliberate gap reads as intentional where a butt join would show every shift. Where two foils share an edge, trap them 0.3mm; keep separate foils 1mm apart. If you're not comfortable setting this up, note it in your submission and our prepress team will add it.

Keep foil 3 mm inside the trim, or bleed it 3 mm past. Never stop in between. The cut lands within ±0.8 mm across a stack, so foil that stops 1 or 2 mm from the edge leaves a margin that visibly wanders from card to card. On a card with a painted edge, stop foil 3 mm short of trim and never bleed it into the paint.

Foil + Other Finishes: File Setup for Combos

Many of Print Peppermint's most popular products combine foil with another finish. Each combination has specific file setup requirements:

• Foil + Blind Emboss (or Deboss): Three layers needed: "CMYK," "FOIL," "EMBOSS." The emboss layer follows the same rules as the foil layer: 100% black vectors on a labeled layer. If an element is BOTH foiled AND embossed (registered emboss + foil), the same element appears on both layers in exactly the same position.
• Foil + Spot UV: Three layers: "CMYK," "FOIL," "SPOT UV." Note: foil and spot UV should generally not overlap on the same area. UV coating on top of foil can dull the metallic effect. Foil on top of spot UV doesn't adhere well.
• Foil + Letterpress: Three layers: "LETTERPRESS" (specify PMS color in the layer name or notes), "FOIL," "EMBOSS/DEBOSS" (if any blind deboss is also present). Letterpress and foil are produced in separate press passes.

General rule for multi-finish files: Every distinct finishing process gets its own clearly labeled layer. If you're combining 3 finishes, you have at least 4 layers (CMYK + one per finish).

Typography in Foil

Measure the actual lettering, not its weight label. Positive foil type stays 7 pt minimum, 8 pt recommended; high-contrast serifs stay 12 pt. A line that clears the 0.1 mm floor does not need boldening to meet the 0.15 mm design target.

High-contrast serifs such as Bodoni and Didot retain the 12 pt foil minimum. Measure their thinnest strokes at printed size: 0.15 mm target, 0.1 mm floor. Do not replace or bolden the customer’s type merely to reach the target.

Outline ALL text. This bears repeating because it's the source of so many production delays. Every letter, every word, every text frame. Check by toggling to Outline mode in Illustrator (Cmd+Y). If you see text bounding boxes instead of paths, you missed something.

Tracking and kerning: measure the narrowest space between foil letters and inside counters. Use 0.25 mm (0.71 pt) as the gap target and 0.15 mm as the floor. Only a below-floor gap needs a local opening.

Reversed text (paper showing through foil): A foil panel with reversed-out white text is a common and beautiful treatment. But the text needs to be at least 10pt, medium or bold, for the letters to remain readable. The counters (holes) in letters like "a," "e," "o," "B," "D" are especially vulnerable — they need to be wide enough that the foil doesn't bridge across and fill them in.

Common Mistakes We See (and How to Avoid Them)

The real-world production issues, from most to least frequent:

1. Foil elements mixed into the CMYK layer. The designer built the layout in one layer with the foil logo in a gold color. There's no separate foil layer. Fix: Always build foil on its own layer from the start.
2. Raster foil elements. The foil layer contains a Photoshop-placed logo at 300dpi instead of a vector path. Raster edges produce jagged die cuts. Fix: Every element on the foil layer must be vector — paths, not pixels.
3. Lines below the floor. Measure at final size: 0.1 mm is the floor, 0.15 mm the design target. Adjust only the below-floor detail, preserving the rest of the mark.
4. Gradients in foil. Foil is either present or absent, not a continuous tone. A screened treatment needs discrete vector dots that clear the 0.1 mm detail floor, target 0.15 mm, and spaces targeting 0.25 mm with a 0.15 mm floor.
5. Live text (not outlined). Fonts get substituted by the die maker's system, producing wrong letterforms. Fix: Select All → Type → Create Outlines, then verify in Outline view.
6. No bleed on foil elements. The CMYK artwork bleeds but foil stops at the trim line. If the cut shifts even slightly, un-foiled paper appears at the edge. Fix: Bleed foil 3 mm past the trim, or keep it 3 mm inside. Never stop between 0 and 3 mm.
7. Overprint instead of knockout. Foil stamps on top of dried ink, reducing adhesion and dulling the metallic effect. Fix: Set foil elements to knockout and verify in Illustrator's Overprint Preview.
8. Flat PDF with no layers. The designer saved with "Flatten" settings that merged all layers. Fix: Save as PDF with layers preserved, or submit the native .ai file alongside.

The Pre-Submit Checklist

Run through this before sending your files:

1. Is the foil on its own dedicated, clearly labeled layer? ("FOIL — Gold — Front")
2. Are all foil elements 100% black (K:100, C/M/Y: 0) vector paths?
3. Are all fonts outlined (no live text anywhere in the file)?
4. Are all images embedded (not linked)?
5. Is the document in CMYK color mode?
6. Do all elements extend 0.125" into the bleed area (including foil)?
7. Are foil lines measured against 0.15 mm target / 0.1 mm floor, and gaps against 0.25 mm target / 0.15 mm floor?
8. Is the smallest foil text at least 7pt (8pt recommended), reversed text 10pt, and any high-contrast serif 12pt?
9. Is the foil set to knockout (not overprint) over CMYK backgrounds?
10. Are there zero gradients, transparency effects, or drop shadows on the foil layer?
11. If combining finishes, does each finish have its own labeled layer?
12. Is the file saved with layers intact (not flattened)?

If you can check all 12, your file is production-ready.

Files ready? Upload them with your order or quote request and we'll start reviewing within 1 business day. Need help with file setup? Our design team can prepare your artwork for US$ 75.

Start a Quote →

What Happens After You Submit

Once you submit your files with your order or quote, our prepress team reviews them — typically within 1 business day. If everything checks out (layers separated, foil within spec, no issues), we prepare a digital proof showing your artwork on the card with print specs, foil placement, and any specialty layers separated for clarity.

Our team gives specific, measured notes: “Please outline the text on the foil layer,” “The gap inside foil is 0.1 mm; open that gap to 0.25 mm,” or “Please supply the foil layer as vector paths.” The rest of the supplied mark stays intact.

Once you approve the proof, production begins. For Studio (hot foil) orders, the die is manufactured from your approved vector file, and your cards are stamped. From proof approval to shipping is approximately 3 weeks.

If you don't have print-ready files, that's OK too. We offer a design recreation service (US$ 75) where our team rebuilds your design to production specifications. You'd supply your logo, brand colors, content, and any references — and we handle the file preparation, foil separation, and print setup. Learn more about pricing →