Screen Printing Underbase: Achieve Opacity on Dark Garments

You've nailed the design. The customer loves it. Then reality hits: they want the artwork printed on a navy hoodie, and your standard cyan, magenta, yellow, black (CMYK) setup looks washed out.

This is where underbase printing becomes your secret weapon. An underbase—typically a white or light-colored layer printed first—lifts color vibrancy on dark garments and ensures opacity without requiring multiple passes of colored ink.

Let's walk through when you need it, how to execute it, and how to price it so your margins don't suffer.

What Is an Underbase and Why You Need It

An underbase is a foundational ink layer—usually white, light gray, or a matching base tone—printed first on a dark garment. Your colored inks then print on top, sitting on a reflective surface instead of absorbing into dark fabric.

Without an underbase on a navy or black shirt:

• Colors appear dull, muted, or translucent
• You need thicker ink deposits to achieve coverage (wasting material)
• The print lacks pop and color separation
• Darker inks may bleed into the fabric base

With a proper underbase:

• Colors appear vibrant and true-to-sample
• Ink adhesion improves over time and washing
• You use less colored ink overall (better margins)
• Design details stay crisp and defined

Types of Underbase Techniques

1. Full Coverage White Underbase

The most common approach. A white layer covers the entire print area, and colored inks print on top.

Best for:

• Logo-heavy designs with many colors
• Photorealistic prints
• High-visibility merchandise (sports teams, event shirts)

Drawback: Uses more white ink, adding cost per garment.

2. Selective (Spot) Underbase

White only appears under specific colors—typically where you want maximum vibrancy.

Best for:

• Multi-color designs where some colors don't need lift
• Budget-conscious orders
• Designs with large solid areas that don't need white underneath

Drawback: Requires careful registration; one missed screen and the spot underbase won't align with the color above.

3. Half-Tone Underbase

A halftone white layer (using dots instead of solid coverage) reduces white ink while still providing opacity boost.

Best for:

• Mid-tone colors (reds, oranges, purples) that need partial lift
• Designs where a solid white would be too visible
• Water-based ink systems (where underbase ink can interact with top layers)

Drawback: Requires precise halftone screen settings; inconsistent pressure can cause dot gain and muddy appearance.

Step-by-Step Underbase Execution

Screen Preparation

1. Separate your underbase onto its own screen using a 230–280 mesh count

   • Higher mesh (280) = finer detail, less ink deposit
   • Lower mesh (230) = thicker white, more coverage
   • Most shops use 260 for balance

2. **Use a sharp, low-durometer squeegee (65–70 Shore) for the underbase

   • Softer squeegee = thicker white ink deposit
   • Harder squeegee (90 Shore) belongs to colored layers

3. **Ensure consistent squeegee pressure and stroke speed

   • Inconsistent pressure = uneven white opacity
   • Aim for 0.5 to 1.5 seconds dwell time on the substrate

Ink Selection

• Use high-opacity white (Plastisol or water-based)
• Brands like Wilflex, Speedball, and Rutland all offer formulations optimized for underbases
• Avoid transparent whites—they defeat the purpose
• White ink should cure separately before colored layers print

Curing the Underbase

Flash cure is essential. A full final cure before color printing is overkill and slows production.

• Flash cure temperature: 250–300°F for 3–5 seconds
• The ink should be tacky but not fully hardened
• This allows the next color layer to grip the white surface

Registering Color Layers

Misalignment ruins an underbase investment.

• Use registration marks on your artwork (crosshairs at corners and center)
• Print the underbase first, then place the next color screen carefully
• Check the first 5–10 pieces before running the full batch
• Tools like Kontraktr can help organize and track your color separations in your digital asset library, reducing manual setup errors

Cost Implications and Pricing Strategy

Material Costs per Garment

Underbase adds roughly $0.15–$0.40 per piece, depending on:

• White ink coverage percentage
• Garment type (cotton absorbs more ink; blends may need less)
• Your ink cost per liter

Colored ink savings:

• Without underbase: 3–4 passes of color to achieve opacity
• With underbase: 1–2 passes of color
• Net savings can offset underbase cost on complex designs

What to Charge

• Add $0.50–$1.50 per piece for underbase service (depending on design complexity)
• Full coverage white underbase: Top end of range ($1.00–$1.50)
• Spot or half-tone underbase: Bottom end ($0.50–$0.75)

This compensates for material, screen preparation, flash-cure dwell time, and labor. Many shops use a per-screen flat fee ($15–$30 per screen) instead, which works better for batch orders.

Common Underbase Mistakes (and How to Avoid Them)

1. Insufficient White Opacity

• Problem: You can still see the dark fabric through the white
• Fix: Lower your mesh count (220–240), use a softer squeegee, or slow your print speed

2. Over-Curing the Underbase

• Problem: Colored inks sit on top of hardened white; they don't grip, and adhesion fails
• Fix: Flash cure only; aim for a tacky surface, not a fully cured finish

3. Underbase Visible After Color Printing

• Problem: White creeps out from under color layers (especially with spot underbase)
• Fix: Tighten your color screen registration; consider slightly smaller color separations

4. Excessive White Buildup on Fabric

• Problem: Garment feels stiff or heavy; customers complain about feel
• Fix: Switch to half-tone underbase or reduce mesh coverage; consider 280 mesh instead of 230

When NOT to Use Underbase

• Light-colored garments (white, cream, pale yellow) — underbase shows and muddles color
• Single-color prints — the color itself has enough opacity
• Super budget orders — underbase adds cost; customer may reject higher quote
• Niche fabrics (heavy velvet, terry cloth) — white may not adhere properly

Pro Tip: Software Organization

Many shops struggle with underbase confusion because they mix color-separated artwork files without clear labeling. When you store artwork in a centralized system, clearly mark which designs require underbase and note your preferred technique (full, spot, or half-tone). This prevents you from running a $300 order with the wrong setup.

Your Action Item

Audit your current orders:

1. Pull the last 10 dark-garment prints you completed
2. Note which ones suffered from faded or dull colors
3. Quote those jobs with underbase pricing (using the ranges above)
4. Run a small test batch to dial in your underbase flash-cure time and screen pressure
5. Re-quote similar future orders with underbase included in your base price

Underbase is one of the highest-ROI techniques in screen printing—it costs little to execute, customers love the results, and it positions your shop as quality-focused. The key is building it into your workflow, pricing, and file management from the start.

Start with one design, nail the process, then scale.