- Color separation splits a design into one layer per color, and each layer becomes its own screen.
- Spot colors suit logos and text, while CMYK is for photos and gradients and shows halftone dots up close.
- Dark garments need a white underbase, which counts as an extra color and an extra screen.
- Convert gradients to halftones and avoid RGB files, live effects and unoutlined text before sending art.
What is Color Separation?
Color separation is the process of splitting a multi-color design into individual layers: one per color. Each layer becomes its own screen. That's the foundation of how screen printing works.
Why it matters:
- One screen per color keeps inks from mixing
- Clean edges, sharp detail, accurate registration
- No guesswork: every color prints exactly where it belongs
Example: A 3-color logo
- Blue layer → Blue screen
- Yellow layer → Yellow screen
- Black layer → Black screen
- Result: 3 screens, 3 setups, 3 print passes
Get the separation wrong and the whole print falls apart. Get it right and you've got something that lasts.
Spot Colors (Pantone)
A spot color is a pre-mixed ink matched to a specific Pantone number. No guessing. No approximating. The color you spec is the color you get.
Why spot colors win:
- Exact color matching via PMS numbers
- Rich, vibrant, solid coverage
- Consistent across every reprint, years later
- Simple to separate, easy to execute
Best applications:
- Logos and brand identity
- Text and simple graphics
- 1 to 6 color designs
- Corporate and licensed branding
The Pantone library gives you:
- 1,000+ solid colors
- Metallic, fluorescent, and pastel options
- Custom mixing for anything outside the standard range
Cost: Each spot color = 1 screen = $32 setup fee
If brand accuracy matters, and it should, spot colors are the right call.
CMYK Process Printing
CMYK uses four ink colors (Cyan, Magenta, Yellow, and Black) to simulate the full color spectrum. Instead of solid ink coverage, it lays down thousands of tiny halftone dots that overlap and blend. Up close you see the dots. Step back and you see a photo.
The upside:
- Full-color and photorealistic results
- Handles gradients and complex imagery
- No theoretical color limit
The tradeoff:
- Halftone dot pattern is visible at close range
- Solid colors look less vibrant than spot inks
- Requires skilled separations to execute well
- Not the right tool for flat, solid color work
Best applications:
- Photographic images
- Complex gradients and color blends
- Full-color artwork that can't be reduced to spot colors
- Designs with 20+ colors where spot printing is impractical
Cost: Minimum 4 screens (C, M, Y, K) = $128 setup
CMYK earns its place when the artwork demands it. For everything else, spot colors are sharper and more consistent.
Spot vs CMYK: When to Use Each
| Factor | Spot Colors | CMYK |
|---|---|---|
| Color Count | 1 to 6 practical | 4 minimum, unlimited |
| Color Accuracy | Exact (PMS match) | Approximate (converts) |
| Vibrancy | High (solid ink) | Medium (dot pattern) |
| Best For | Logos, text, solids | Photos, gradients |
| Setup Cost | $32 × color count | $128 (4 screens) |
| Skill Required | Basic separation | Advanced separation |
| Consistency | Excellent across reprints | Good (may vary slightly) |
The rule is simple: Spot colors for logos and brand work. CMYK for photos and complex gradients, and only when there's no other way.
Underbase for Dark Garments
Printing on a dark garment without an underbase is a mistake. Fabric color bleeds through the ink and kills your vibrancy: reds go purple, whites go gray. An underbase fixes that.
What it does:
- White ink is printed as the first layer
- It blocks the garment color from affecting what's on top
- Colors printed over the underbase appear full-strength and clean
The process:
- Print white underbase first
- Flash cure (partially dry the ink)
- Print colors on top
- Full cure
What it costs:
- Underbase counts as an additional color
- A 2-color design on a dark garment = 3 screens
- Setup: 3 × $32 = $96 (vs. $64 on a light garment)
Real-world example:
- Navy garment, 2-color logo (red + white text)
- Without underbase: Red looks purple, white looks gray
- With underbase: Red is vibrant, white is crisp
If you're printing on black, navy, charcoal, or any dark color, budget for the underbase. It's not optional if you want quality results.
Halftones for Gradients
Screen printing lays down solid ink. It can't literally fade. Halftones solve that problem by using varying dot sizes to create the illusion of a gradient: large dots where the color is dark, smaller dots where it lightens out. Your eye blends them together.
Dot shape options:
- Round: the standard, works for most applications
- Elliptical: smoother gradient transitions
- Square: sharper, more defined transitions
Line screen (LPI):
- Measured in lines per inch
- 85 to 100 LPI is standard for garment printing
- Higher LPI delivers finer detail, but demands more precision to execute
Best applications:
- Fade and shadow effects
- Varying color intensity within a design
- Gradient transitions that can't be achieved with solid spot colors
If your artwork has a gradient, it needs halftone conversion before it can be screened. Don't skip this step.
The Separation Process
Color separation isn't magic. It's a disciplined, step-by-step process. Here's how it works.
Step 1: Artwork Analysis
- Count colors, identify spot vs. CMYK requirements
- Determine underbase needs based on garment color
- Flag any gradients that need halftone conversion
Step 2: Color Separation
- Isolate each color onto its own layer
- Convert to bitmap format for screen output
- Apply halftones where gradients exist
- Add registration marks for alignment on press
Step 3: Film Output
- Each separated layer prints to clear film: one film per color
- Output at 2400+ DPI for clean, sharp edges
- Films are labeled by color and print order
Step 4: Screen Exposure
- Screen is coated with light-sensitive emulsion
- Film is placed over the screen and exposed to UV light
- Unexposed emulsion washes away, leaving the image
- One screen per film, every time
Every step matters. A mistake at separation shows up on press, and on the finished garment.
File Setup for Separation
Send us the right files and the process moves fast. Send us the wrong ones and we're doing your job before we can do ours.
Vector files (AI, EPS, PDF):
- Each color on its own named layer
- Layer names that match the color (e.g., "PMS 185 Red")
- Pantone numbers specified
- Text converted to outlines: no live fonts
Raster files (PSD, TIFF):
- Each color on a separate channel
- 300+ DPI at final print size
- CMYK or Spot color mode only
- Transparency flattened before sending
Include with your files:
- Total color count
- Pantone numbers for any spot colors
- Note if garment is dark (underbase needed)
- Print order if known (light to dark)
- Garment color
Do not send files with:
- RGB color mode (it will shift on conversion)
- Live effects like drop shadows or glows
- Transparent gradients (convert to halftone first)
- Unoutlined text
Set up your files correctly and you'll save time, money, and back-and-forth.
Separation Mistakes
These are the most common ways artwork fails, and how to avoid every one of them.
RGB files RGB is for screens. Screen printing uses ink. RGB to CMYK conversion causes color shifts you won't like. Fix: Design in CMYK or Pantone from the start.
Too many colors Every color is another screen, another $32 setup fee. Fix: Simplify the design. Four to six colors is the sweet spot for cost-effective screen printing.
No underbase note Dark garments need an underbase. If you don't tell us, we have to assume, and assumptions cost time. Fix: Specify garment color upfront. Every time.
Gradients without halftone conversion Solid ink can't fade. A gradient that hasn't been converted to halftone can't be screened. Fix: Convert all gradients to halftone before submitting.
Tiny text Anything under 6pt won't hold on a screen. The emulsion can't support it. Fix: Keep text at 8pt minimum for screen printing.
Hairline strokes Lines under 1pt break down in the screen and disappear in the print. Fix: Minimum 1.5pt stroke weight, no exceptions.
Unseparated layers When layers aren't separated, we have to do it manually. That's an art fee on top of your setup cost. Fix: Provide separated layers. It's faster for everyone.
Get a Quote
Ready to print? We handle color separation in-house and we know what it takes to get your artwork right the first time.
Three ways to get started:
Business Quote Form: Upload your artwork and get a fast, accurate quote
Email: sales@arnoldprints.com: Attach your files and note your garment color
Call: (561) 323-7573: Talk directly to someone who knows screen printing
Don't sit on a design that's ready to go. Submit your artwork today and we'll tell you exactly what it'll take to get it on a shirt.
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