Understand the Underbase

What Is an Underbase?

An underbase (also called underlay or base coat) is a foundation layer of ink printed before the actual design.
Its purpose is simple: create a consistent, bright, and stable surface so the design colors appear vibrant, smooth, and accurate.

Underbases are most commonly printed in white, but grey or black are used for:

• Dye-migration blocking
• Better tonal balance
• Preventing color shift (e.g., red turning pink over white)

Without a proper underbase, prints on dark or saturated garments often look faded, dull, or inconsistent.

Why Use an Underbase?

A well-designed underbase enhances almost every aspect of the final print:

✔ Prevents Garment Color Interference

Stops the shirt color from bleeding through the inks.

✔ Boosts Vibrancy & Opacity

Creates a bright canvas for semi-transparent inks.

✔ Reduces Fibrillation

Helps flatten surface fibers, giving the print a smooth finish.

✔ Acts Against Dye Migration

Especially on polyester or blends where dyes migrate when heated.

✔ Supports Special Effects

Glitters, fluorescents, puffs, and 3D effects require a stable base.

✔ Improves Print Durability

Allows inks to sit on top of the fabric rather than sinking into it.

An underbase is one of the most powerful tools in achieving premium, consistent print quality.

When Should You Use an Underbase?

You should use an underbase when:

• Printing light colors on dark garments
• Using semi-transparent inks (water-based, discharge, plastisol blends)
• Customers request high opacity finishes
• You need to print on polyester or sublimated fabrics
• The design includes gradients or detailed elements
• You need to flatten the garment fibers

You may skip an underbase when:

• Printing dark ink on a light garment
• You intentionally want a vintage/faded look
• Using extremely opaque high-solids inks
• Printing reflective inks (which should never have an underbase)

Types of Underbases

1. Solid Underbase

• Full, opaque layer
• Very stable and bright
• Creates a heavier hand feel

Best for spot-color designs.

2. Halftone Underbase

• Uses dot patterns to reduce ink deposit
• Creates smoother gradients
• Reduces print thickness

Best for simulated process printing, photorealistic images.

3. Colored Underbase

Examples: grey, light blue, tan, black

Use it when:

• White creates color shifts
• You need balanced tonal depth
• You’re blocking dye migration

4. Clear Underbase

A gloss-like layer used to tame fibers and enhance detail without affecting color tone.

Factors in Creating a Successful Underbase

Ink Properties

Choose inks with:

• High opacity
• Thick, creamy consistency
• Fast flash-gel times

Mesh Count

Typical ranges:

• 110–160 tpi (43–62 t/cm) for thick, opaque plastisol
• 180–230 tpi (70–90 t/cm) for detail and halftone underbases

Screen Tension

Higher tension results in:

• Cleaner ink release
• Smaller dot gain
• Sharper detail

Flashing

The underbase must be gelled, not fully cured.

Over-flashing leads to:

• Cracking
• Poor adhesion

Artwork Choking

Choking shrinks the underbase slightly (0.5–2 px) so its edges never peek out beyond the top colors.

Proper Application Technique

Step-by-Step

1. Lay Down the Base

• Use consistent flood stroke
• Apply a hard flood + lighter print stroke
• Avoid pushing ink deep into the fibers

2. Flash to a Gel

Ideal state:

• Dry to the touch
• Matte finish
• No ink pickup on finger

Never fully cure the underbase before printing top colors.

3. Print Top Colors

This is where opacity and detail come to life.

4. Optional: Print-Flash-Print (PFP)

Used for extremely bright whites:

• Print underbase
• Flash
• Print again
• Flash lightly
• Add top colors

5. Final Cure

Follow exact ink manufacturer’s curing instructions.

Potential Downsides

While underbases are essential, they have drawbacks:

• Heavier hand feel (especially solid underbases)
• More production time (extra screen + flashing)
• Registration challenges if choking is incorrect
• Risk of dye migration if underbased incorrectly
• Over-flashing issues causing poor adhesion

However, these problems are solved with correct setup, experience, and proper technique.

The Future of Underbases

Automation & Robotics

Automated underbase control reduces human error.

Digital-Hybrid Underbases

Combining screen + digital printing results in:

• More accuracy
• Less ink waste
• Superior detail

Smart Mesh & Nanotech

Modern meshes and inks will adjust flow and deposit amount intelligently.

Sustainable Underbases

Growth in:

• PVC-free inks
• Water-based underbases
• Low-temperature curing solutions

Advanced Dye Blocking

Specialized migration-blocking formulations for polyester, nylon, and sportswear.

Conclusion

The underbase is the unsung hero of screen printing.
It determines how bright, crisp, and durable a print will be — especially on dark garments.

Mastering underbases means mastering:

• Color accuracy
• Detail
• Print longevity
• Customer satisfaction

Whether you’re printing simple spot colors or advanced photorealistic designs, understanding underbases is essential for professional, consistent results.

Questions & Answers on Underbases in Screen Printing

When is an underbase important?

Whenever printing light inks on dark garments or when dye migration is likely.

Can an underbase be another color besides white?

Yes. Grey, black, tan, or blue underbases can stabilize color and prevent shifts.

Is an underbase always required?

No. Some designs, inks, and garment colors work without one.

Solid vs. halftone underbase?

Solid: More opaque, heavier

Halftone: Less ink, smoother gradients

Why only gel the underbase during flashing?

Fully cured layers don’t bond well with top inks.

Does it affect garment feel?

Yes. More ink = heavier hand feel.

What factors should I consider?

• Garment color
• Fabric type
• Ink opacity
• Design complexity
• Customer expectations