Underbase White in Screen Printing: When Do You Need It and How Much?
Designs that look bright on screen go dull and muddy on dark shirts. An underbase white is almost always the fix. Here is when you need one, how heavy it should be, and how we handle it in separation.
Your design looks bright on screen, but on a black shirt the colours come out dull and muddy. The fix is almost always an underbase. Here is when you need one, how heavy it should be, and how we handle it in separation.
What is an underbase white?
An underbase is a layer of white ink printed first and flash-cured, with the colours printed on top of it. On a dark or coloured garment, the fabric darkens any ink laid directly onto it. The white underbase gives your colours an opaque base to sit on, so they read bright and true instead of sinking into the shirt.
When do you need an underbase?
The short answer: whenever the garment is darker than the lightest colour in your design. In practice that means:
- Dark garments (black, navy, deep shades): almost always
- Mid-tone garments (red, royal blue, grey): usually, for any light or bright colours
- Any time you want bright, opaque results on coloured fabric
Without it, yellows, reds, and light tones are the first colours to disappear into the cloth.
When can you skip the underbase?
- White or very light garments, where the fabric is already your white base
- Designs printed in dark inks on light garments
- Intentionally soft, vintage, or tonal looks, where the colours are meant to blend into the shirt
If you are not sure, tell us the garment colour and the effect you want, and we will advise.
How much underbase is too much?
This is where most problems start. A heavy, solid underbase under the whole design causes:
- A thick, plasticky hand feel and poor breathability
- Ink build-up that can crack or trap moisture
- Loss of fine detail as the dots fill in
- Longer flash and cure times that slow the press
The goal is enough white to support the colours and no more. A good underbase is built to match the artwork, lighter under light areas and held back in the highlights, rather than a full flood of white everywhere.
Does the garment colour change the underbase?
Yes. A black shirt needs a fuller underbase than a charcoal or a navy, because there is more darkness to cover. We adjust the underbase weight to the specific garment, so the same design on black and on charcoal each get the right amount, instead of one heavy underbase that is too much on the lighter shirt.
How do we build the underbase channel?
In separation, the underbase is generated from the colours that sit on top of it, then refined:
- It is choked slightly (pulled in from the edges) so the white does not show past the colours if registration drifts on press
- Highlights and very light areas are managed so the print keeps its detail and does not go chalky
- The weight is tuned to the garment colour and to the ink and mesh you print with
The same principle applies to DTF and DTG, where a white layer sits under the colour. The handling is more automated there, but the idea is identical.
Getting your underbase right
If your prints look dull on dark garments, or you are fighting a heavy hand feel and lost detail, the underbase is usually the cause: missing, too heavy, or not choked. Send us your artwork and the garment colour, and we will separate it with an underbase built for that exact job. We respond to quotes within 1–2 hours, and most separations are delivered within 2–4 hours.
Ready to get it right? Submit your artwork or see how we handle simulated process separation.
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