How the expansion actually happens
The ink carries a chemical blowing agent. When the printed area passes through the cure tunnel, the agent decomposes and releases gas, and the ink film expands. The height is set by how much agent is in the mix, the deposit thickness, and the cure temperature and dwell time.
Because the cure and the expansion are the same event, the process window is narrower than a standard plastisol print. Under-cure gives a raised print that will crack; over-cure gives a print that has already peaked and flattened. This is why puff is quoted as a separate pass rather than an add-on to an existing screen job.
A second, more controllable route is a puff transfer: the same expanding ink printed on film and pressed onto the garment. Setup disappears, height is more even, and fine detail still closes up.
Why the artwork has to change
Expansion pushes the ink outward as well as upward, so every gap in the design narrows. A 1 mm gap in the file becomes a 0.4 mm gap on the shirt, or a closed one. Serif type, thin rules and small reverses are the usual casualties.
The workable rule is a minimum stroke width of about 2 mm and a minimum gap of the same, at final print size. Type under roughly 12 pt closes up regardless of how it is separated.
The design has to be re-drawn rather than scaled down. A logo that arrives as a 300 mm chest print and then gets reduced to a 60 mm left-chest version will fail at the smaller size, because the stroke widths fall below the expansion tolerance.
- Minimum stroke: about 2 mm at final print size.
- Minimum gap: about 2 mm, and more on textured fabric.
- No fine serifs, no hairline reverses, no type under ~12 pt.
Puff versus high density
Both are raised, and buyers confuse them constantly. Puff expands the ink itself and has a soft, slightly rubbery feel. High density deposits a thick, hard film of plastisol through a low mesh screen and gives a flat-topped, sharp-edged raised panel with a much crisper finish.
High density holds fine detail far better and is the right answer when the raised area is a logo with small elements. Puff is the right answer when the raised area is a large shape and the texture is the point.
Neither is a good match for a garment that will be tumble dried at high heat — the puff film softens and the high-density edge softens with it, so both are better on a line-dry programme.
Which fabrics hold it
Puff needs a surface that will not move under the deposit. A 160–180gsm jersey stretches as the screen lifts, so the ink film breaks at the edges and the print looks ragged. From about 220gsm upward the knit is stable enough to hold a clean edge.
On a garment-dyed or heavily washed body the surface is uneven before the print goes down. Puff on a sun-faded finish reads as deliberate texture; puff on a slub or heavy-rib surface reads as a defect, because the expansion follows the surface ridges.
Very dark colours need a white underbase for the ink to read, which adds a layer under the puff and softens the height. A white or light-grey body gives the most visible height for the same deposit.
What to send for a puff quote
Vector artwork at final print size, the placement and dimensions, the fabric weight and colour, the quantity per colour and style, and whether the raised area is one shape or a multi-colour design.
If the artwork uses type below 12 pt or hairline gaps, expect a redraw before the order. That redraw is the step that saves a whole run — it is not a delay in the process, it is the process.
Puff print is one of six decoration routes on the custom hub, alongside screen printing, embroidery, DTG and DTF, garment dyeing, and private label with custom neck labels.