Printing on spandex (or any stretchy synthetic blend) can yield vibrant, flexible designs---if the ink stays where you want it. Ink bleeding not only ruins the visual impact but can also compromise the fabric's stretch and durability. Below is a step‑by‑step guide to keep your colors crisp, your seams intact, and your customers (or yourself) thrilled with the final result.
Understand Why Ink Bleeds on Spandex
| Cause | What Happens | How It Affects the Print |
|---|---|---|
| High water content in ink | Ink spreads as water seeks equilibrium across the fibers. | Blurry edges, loss of detail. |
| Low cure temperature | Ink doesn't fully polymerize, leaving a tacky surface. | Ink smears during handling or laundering. |
| Improper pretreatment | Fiber surface remains oily or coated with finishes. | Ink cannot bond, so it flows into adjacent fibers. |
| Excessive stretch during printing | Fabric tension changes under the platen. | Ink migrates when the fabric returns to its relaxed state. |
Knowing the root cause will help you choose the right combination of inks, pretreatments, and machine settings.
Choose the Right Ink for Stretch
| Ink Type | Best For | Key Benefits | Typical Curing Temp |
|---|---|---|---|
| Plastisol (high‑solids) | Heavy‑weight spandex blends, bold colors | Thick, sits on top of fibers, excellent opacity | 320‑340 °F (160‑170 °C) |
| Water‑based discharge | Light‑weight, high‑stretch performance wear | Soft hand, breathable | 300‑320 °F (150‑160 °C) |
| UV-curable | Small runs, quick turnaround | Cures instantly, minimal heat stress | UV‑lamp (no heat) |
| Sublimation inks (polyester‑coated spandex) | All‑over prints, vibrant photorealistic images | Ink becomes part of the fiber, no surface bleed | 380‑400 °F (193‑204 °C) |
Pro tip: For most everyday spandex garments, a high‑solids plastisol or a specially formulated water‑based stretch ink provides the best balance of colour pop and flexibility. Avoid low‑viscosity inks unless you're using an UV system that fully cross‑links the polymer.
Pretreatment is Non‑Negotiable
- Clean the Fabric
- Apply a Stretch‑Specific Pre‑Coat (optional but highly recommended)
- Check for Residual Moisture
- Any trapped moisture will cause the ink to migrate. Use a moisture meter or simply feel---fabric should be dry to the touch.
Optimize Your Printing Machine Settings
| Setting | Recommended Range for Spandex | Why It Matters |
|---|---|---|
| Platen Pressure | Light to moderate (just enough to flatten without crushing fibers) | Too much pressure squeezes ink into fibers, encouraging bleed. |
| Print Speed | 12‑16 inches per second (ips) for plastisol, slower for water‑based | Faster speeds reduce dwell time, limiting ink spread. |
| Ink Deposit (thickness) | 10‑15 mil for plastisol, 8‑12 mil for water‑based | Too thick = excess ink, too thin = incomplete coverage---both lead to bleeding. |
| Curing Time | 15‑20 seconds at target temperature (check manufacturer) | Under‑cure leaves tacky ink; over‑cure can damage elasticity. |
Tip: Perform a "pre‑cure" test on a scrap piece: print a small swatch, cure, then stretch the fabric 20 % and release. If the print cracks or smears, adjust temperature or speed.
The Curing Process -- Get It Right the First Time
- Heat Up the Conveyor -- Set the conveyor to the ink's recommended cure temperature. Let it stabilize for at least 5 minutes before printing.
- Use a Heat‑Reflective Cover -- A thin silicone sheet over the print area helps retain heat and ensures even curing without overheating the surrounding fabric.
- Monitor the Exit Temperature -- The fabric should exit the oven at no less than 10 °F (5 °C) above the ink's cure point. Use a non‑contact infrared thermometer for quick checks.
- Cool Gradually -- Rapid cooling can cause micro‑cracks that later result in feathering. Allow the printed panel to cool on a flat, non‑sticky surface for 30‑60 seconds before handling.
Post‑Print Handling & Finishing
| Action | How to Do It | Reason |
|---|---|---|
| Gentle Stretch Test | Stretch the fabric 10‑15 % in multiple directions. | Confirms ink adhesion under real‑world movement. |
| Cold‑Water Rinse (optional) | Light rinse at 40 °F (4 °C) for 30 seconds. | Removes surface tack and reduces "catch‑up" bleed after washing. |
| Low‑Heat Press | Press at 260‑270 °F (127‑132 °C) for 5 seconds to flatten any minor uplift. | Levels the surface without melting the spandex fibers. |
Troubleshooting Common Bleed Scenarios
| Symptom | Likely Cause | Quick Fix |
|---|---|---|
| Ink feathering at the edges | Insufficient platen pressure + high ink viscosity | Reduce viscosity (add a compatible reducer) and increase platen pressure slightly. |
| Smudging after washing | Under‑cured ink | Raise cure temperature by 10 °F (5 °C) or increase dwell time by 2‑3 seconds. |
| Brittle prints that crack on stretch | Over‑cured or using a non‑stretch ink | Lower cure temperature or switch to a flex‑grade water‑based. |
| White halos around darker areas | Ink bleeding into adjacent fibers during cure | Decrease ink deposit thickness and ensure the pretreatment is fully dry. |
Pro Tips to Keep Ink Bleeding at Bay
- Use a "dummy" layer -- Print a thin layer of clear plastisol or water‑based binder first, cure it, then print the colored layer on top. The first layer acts as a barrier.
- Control ambient humidity -- Aim for 40‑55 % relative humidity in the production area. High humidity adds moisture to the fabric and encourages ink spread.
- Mind the stretch direction -- Align the print's critical details perpendicular to the primary stretch direction; this reduces the mechanical stress on those areas.
- Batch test -- For new fabric‑ink combos, run a 5‑sample batch (different colors, thicknesses) before committing to a full run.
Wrap‑Up
Printing on stretchy spandex can be a rewarding venture when you master the balance of ink chemistry, fabric preparation, and precise machine settings. By:
- Selecting an ink formulated for stretch,
- Pretreating the fabric to remove contaminants,
- Fine‑tuning platen pressure, speed, and cure temperature, and
- Verifying the print with stretch tests before mass production,
you'll dramatically reduce the risk of ink bleeding and deliver vibrant, durable prints that move with the wearer---not against them.
Happy printing---and may your colors stay as elastic as your fabrics!