Underbase
Print method — one of 27 in the glossary
A layer of white ink printed first, underneath the coloured artwork, so the colours read accurately on a dark garment rather than being tinted by the fabric beneath. Necessary for most printing on dark blanks and the reason those prints feel heavier and cost more. Sublimation cannot lay one down, which is why it cannot print on dark fabric at all.
Colour needs something to sit on
Screen printing inks are not fully opaque. Print red directly on navy and the fabric shows through, so the red reads as a dull maroon.
An underbase is a layer of white printed first, in the shape of the design, giving the colours a neutral ground so they read as intended.
It is flashed — briefly heated — before the colours go on top, so they do not smear into it.
What it costs
A screen and a station, so it adds to setup cost as if it were an extra colour.
A flash cycle per garment, which slows the run.
And hand. An underbase plus colours is two or three ink layers thick, which is most of why prints on dark shirts feel heavier than the same design on white.
When you can skip it
On white and very light garments, where the fabric is already the neutral ground.
With discharge ink, which removes the garment's dye rather than covering it, so the design sits in the fabric with almost no hand — though it only works well on reactive-dyed cotton.
With DTF, where the transfer carries its own white layer on the film rather than on the shirt.
Common questions
- What is an underbase in screen printing?
- A layer of white ink printed first, in the shape of the design, so the colours on top read accurately instead of being tinted by a dark garment underneath.
- Do you need an underbase on a black shirt?
- For accurate colour with plastisol, yes. The alternatives are discharge ink, which removes the garment's dye instead, or a DTF transfer, which carries its own white layer.
- Why do prints on dark shirts feel thicker?
- Because there are more ink layers — an underbase plus the colours on top. That extra thickness is the price of the colours reading correctly.
Where this comes up
See also
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