Graphic Cotton — Printing graphics on cotton: how | graphicotton.com
'Cotton' is not a specification. Weight in gsm, yarn construction, thread count and colourfastness are what a printer can actually work to.
A purchase order that just says 'cotton' tells a printer almost nothing. The specification that controls the print is weight in grams per square metre, yarn construction, thread count and preshrinking — and each one controls a different failure mode.
Weight first. T-shirt jersey normally runs 140-180 gsm, and 180 gsm is the common all-rounder because it is opaque enough for dark inks and stable under a squeegee. Combed ring-spun cotton at 180-200 gsm presents a smoother surface and holds a print more cleanly; lighter 110-130 gsm poly-cotton drapes better but changes the ink chemistry, because the polyester component will not take water-based ink and the print needs an underbase.
On narrow screens, swipe or scroll the plate sideways.
Yarn and thread count control detail. A ring-spun 30/1 or 40/1 yarn holds fine lines that a 20/1 carded single jersey smears, which is why detailed artwork and carded blanks disappoint together. Thread count matters less than GSM in practice: combed ring-spun is properly specified as 100-150 threads per inch, and a marketing number above that rarely changes the print.
Preshrinking controls geometry. Untreated cotton shrinks 3-5% in the wash, and a printed panel that shrinks at a different rate from the body puckers around the design. Blanks should be washed at 60 °C and preshrunk to a tolerance of about 2-3% before printing — this single step matters more than the fibre content on the label.
Colourfastness closes the specification. A 100% cotton knit absorbs 7-8% of its weight in water, and dark garments bleed into a shared wash for the first 1-3 cycles; water-based ink raises absorption at the printed area, so print and fabric should be pre-washed together before sale. Method constraints follow from the fibre: DTG needs at least 80% natural fibre and a white or light base, and discharge works only on cotton and cotton-rich blends. The method-by-method numbers are compared at /screen-print-vs-dtg, and the full ordering sequence is at /printing-order-checklist.
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