Mastering the Art of Printing Underbases in Screen Printing
In screen printing, a great underbase is the unsung hero that can make or break the final print. Whether you're printing on manual or automatic presses, understanding how and when to use underbases—especially white or alternative colors—is key to vibrant, consistent, and long-lasting prints. Here’s a breakdown of best practices to elevate your underbase game.
Choosing the Right Mesh Count for Underbases
The mesh count directly affects ink deposit, edge definition, and print clarity. For underbases:
- Manual Press: Use a 110–125 mesh. These meshes lay down a heavier ink deposit to ensure opacity and coverage.
- Automatic Press: Use a 160–180 mesh (preferably thin thread). Autos have more control and pressure, allowing for finer meshes that deliver smooth yet opaque bases.
Using thin thread mesh increases open area, allowing for better ink flow and faster flashing without overloading the garment.
When You Don’t Need an Underbase
Not every print needs a white base underneath:
- Dark Inks on Light Garments: Black, navy, and forest green often read clearly and vibrantly on white, ash, and light heathers.
- Color Shift Concerns: Some colors, like royal blue, maroon, and wine, may appear overly bright or shift in hue when printed over white. In these cases, consider skipping the underbase or switching to a toned underbase (more on that below).
When to Use a Gray Blocker Underbase
A gray blocker base is critical when battling dye migration or ghosting issues on synthetic blends and sublimated garments. Use it when:
- Printing on polyester, tri-blends, or heathers that contain sublimated dyes.
- You need to neutralize a background tone before laying down colors.
- You're printing white or pastel inks on difficult garments like red or royal poly.
Gray blocker bases usually print as a bottom layer under the white base. Use a tighter mesh (180–200) and cure thoroughly.
Alternative Underbase Colors: White Isn’t Always Right
For vintage looks or to intentionally tone down top colors, use non-traditional underbase shades like:
- Gray – reduces the pop and creates a muted aesthetic (great for distressed or tonal designs).
- Tan or Brown – ideal for earth-tone palettes or warm artwork.
- Soft White or Natural – helps blend better with off-white garments.
These options are perfect for creating a more textile-friendly appearance or for mimicking water-based ink aesthetics while still using plastisol.
Halftone Underbases: When Less is More
Not all underbases need to be solid. Halftone underbases allow for smoother gradients and a softer feel, and are particularly useful when:
- You're printing illustrative or vintage art styles.
- The top colors don’t need full opacity.
- You want to reduce ink buildup and printing pressure.
Use halftones with 180–230 mesh screens, depending on detail. Keep your dots open and test flash carefully—dot gain can ruin the subtlety.
Creating a Smooth and Printable Surface
A properly flashed underbase is essential to avoid fibrillation, poor top color registration, or texture issues. Best practices:
- Flash temp: 220–250°F surface temp, 2–6 seconds. It should be dry to the touch but not fully cured.
- Check the feel: If it’s too tacky or too gummy, back off on ink deposit or raise your flash head.
For high-volume shops or precision underbases:
- Use a Stampinator to flatten and gel the base perfectly.
- Try a roller screen for leveling the underbase during the flood pass.
These tools help deliver consistent smoothness and improve top layer registration.
Final Takeaways
A great underbase is the foundation of a great print. By tailoring your approach to mesh count, garment type, and desired final look, you’ll not only produce better prints—you’ll improve efficiency, hand feel, and customer satisfaction.
Want help building the perfect underbase setup for your shop? Reply to this email to schedule a personalized consult or equipment demo.
