Creating artwork for silk screen film output requires strict adherence to prepress standards. Below is the complete specification.
1. File Format Requirements: Must Be Vector
Never use raster formats like JPG or PNG directly. The artwork must be in vector format.
- Preferred Formats: .ai (Adobe Illustrator), .cdr (CorelDRAW), .eps, .pdf.
- Why: Silk screen film needs to be exposed onto a mesh screen. Vector graphics maintain sharp, clean edges at any size. If a logo or text is a bitmap, it will have jagged edges, resulting in a rough, low-quality stencil.
- Convert to Outlines (Curves): This is the most critical step. Before submitting an .ai or .cdr file, you must convert all text to outlines (create curves). This prevents font substitution and layout corruption if the factory doesn’t have your specific fonts.
2. Size & Scale: Must Be 1:1
- 1:1 Scale: The size of the artwork on your artboard must be the exact final printed size on the product. For example, if the logo should be 20mm wide, set your artboard to 20mm.
- Bleed: If the print needs to cover a specific area completely, add a small bleed (usually 1-2mm) beyond the intended edge.
- Avoiding Obstructions: Design must account for product features like rounded corners, screw holes, assembly gaps, and areas that are not flat.
3. Color Specification: Spot Colors (Pantone System)
Silk screen is not full-color process printing (CMYK). Generally, one color requires one separate screen.
- Pantone (PMS): All colors must be labeled with a Pantone (PMS) number, e.g., PMS 186 C (Red). The factory will mix ink to match that specific Pantone standard, rather than trying to simulate it with process colors.
- Color Separation (Layers/Pages): You must separate colors into individual layers or artboards.
- Example: A logo with 3 colors (Black, Red, Gold) must be prepared as 3 separate layers. The factory will create 3 separate screens and print them sequentially.
- Black & White Separation File (Film Output): When exporting a PDF for direct film output, convert each color layer to pure Black (K=100%). Film imagesetters only register black; the purer the black, the better the opacity and exposure quality.
4. Process Limitations: Minimum Line Width & Spacing
This is the most overlooked yet critical aspect. Screen printing pushes ink through a mesh. If lines are too thin, the ink won’t hold and will break.
- Minimum Line Width: 0.15mm ~ 0.2mm (approx. 0.006 – 0.008 inches). For general printing, 0.2mm is safer. Below 0.15mm, lines will likely break or print blurry.
- Minimum Spacing (Gap): The distance between two lines (or the open space in a design) must be no less than 0.15mm. Smaller gaps will fill in with ink.
- Minimum Font Size: For fonts with complex strokes (like Serif or Blackletter), the x-height should be at least 1.0mm. For extremely thin fonts, consider using a bolder weight.
5. Halftones & Gradients
If your design requires a gradient or drop shadow:
- Must Use Halftones: Convert the continuous gradient into a pattern of small dots (halftone screen). You cannot output a continuous gradient directly, because a screen either lets ink pass (open) or blocks it (closed). The illusion of a gradient is created by varying the size and spacing of dots.
- Lines Per Inch (LPI) / Screen Ruling: For standard product silk screen, the halftone frequency is typically 35 LPI to 75 LPI. Higher LPI (finer dots) is harder to print without clogging; lower LPI gives more visible grain.
6. Artwork Package & Markings
A complete, professionally prepared submission for a silk screen film should include the following:
- Printing Location Diagram: Place the 1:1 artwork on an A4 page. Use a red dashed outline to show the exact print area. Add dimension lines with tolerances and clearly call out the Pantone numbers.
- 1:1 Source File: Provide the vector file (with fonts outlined) at exact 1:1 scale.
- Film Output PDF (Optional): If you are generating the film yourself, provide a single PDF with each color separation as a pure black plate.
Summary Checklist
| Check Item | Requirement | Consequence of Ignoring |
| Format | AI / CDR Vector, Text to Outlines | Missing fonts, scrambled layout |
| Scale | 1:1 (Actual printed size) | Printed size will be wrong |
| Color | Labeled with Pantone (PMS) number | Severe color mismatch |
| Line Width | Line ≥ 0.15mm | Broken lines, incomplete print |
| Spacing/Gap | Gap ≥ 0.15mm | Ink bleeding, blurred details |
| Layers | Multi-color = Multi-layers | Impossible to separate screens |
Core Advice
Silk screen printing excels at sharp lines, solid colors, and high contrast. It struggles with complex gradients and extremely fine text. For successful film output and final print quality, keep your design simple, high-contrast, and geometrically sharp.