People see a finished print and assume a machine just stamps it on. The real process has more steps than most folks expect, and each one affects how your shirt turns out.
We run screen printing out of our shop in Saskatoon, so we get asked how it all works a lot. Here's how screen printing works, step by step, from the artwork file to the folded shirt. We've kept it general, since every shop's equipment and inks differ. If a word trips you up, our screen printing glossary has plain-language definitions.
How screen printing works: the short version
A screen is a frame with fine mesh stretched across it. A light-sensitive coating called emulsion is spread on the mesh, then hardened everywhere except where your design goes. Ink gets pushed through those open areas onto the shirt, then heat sets it.
One screen prints one colour. A three-colour design needs three screens, lined up so each colour lands exactly where it should. That's the whole idea. The rest is detail, and the detail is where good prints come from.
Step 1: Artwork and colour separations
Everything starts with the design. Clean, high-resolution artwork makes every step after it easier. We won't repeat the file prep details here; our guide to screen printing artwork requirements covers that.
Once the art is ready, it gets split into separations. The print industry federation FESPA describes separation as the process by which original artwork is separated into individual colour components for printing. Each colour becomes its own black-and-white layer, and each layer will become its own screen.
Registration marks, small crosshairs, get added to every separation. They're the shared reference points that let the printer line the screens up later.
Step 2: Printing the film positives
Each separation is printed onto clear film, so the design shows up as solid black on a transparent sheet. Emulsion maker Chromaline recommends printing the film as dark as possible.
The darkness matters because the film's job is to block light. Any grey or thin spot lets light through, and that part of the stencil won't wash out cleanly.
Step 3: Cleaning and coating the screen with emulsion
Before any coating goes on, the mesh needs to be clean. Screens get degreased to strip out dust, oils and residue, because emulsion won't grip dirty mesh evenly.
Then comes the emulsion. It's applied with a scoop coater, a trough that holds the liquid and spreads it in one smooth pass up the mesh. Chromaline's guide describes coating the print side first, then the squeegee side, and notes most emulsions call for one coat on each side.
The coated screen dries flat, print side down, in a dark and clean space. Chromaline says the drying temperature shouldn't go above 110°F (43°C). Humidity matters too: Grimco's prep guide suggests keeping relative humidity at 40% or lower and warns that exposing a screen before it's fully dry is one of the most common causes of poor screen prep.
Step 4: Exposing the screen
This is where the stencil is actually made. The film positive is taped to the screen, and the screen goes under a UV light source.
Light hardens the emulsion wherever it hits. Under the black parts of the film, the light is blocked, so that emulsion stays soft. Exposure time depends on the emulsion, the mesh and the light, which is why printers use exposure charts and test strips rather than guessing.
Step 5: Washing out the stencil
After exposure, the screen gets rinsed with water. The soft, unexposed emulsion washes away and leaves open mesh in the exact shape of the design. The hardened emulsion stays put and becomes the stencil.
Chromaline suggests gently wetting both sides with lukewarm water, waiting about 30 seconds, then washing the print side until the image is fully open. Grimco adds that a short soak before washout helps fine detail release without blasting the stencil off.
Step 6: Taping, touch-ups and registration
Once the screen dries again, it's checked over on a light table. Tiny pinholes get touched up with blockout, and the edges of the screen get taped so ink can't leak where it shouldn't.
Next, the screens go on the press. For a multi-colour job, each one is lined up using those registration marks until every crosshair meets the same reference point. Printable Press recommends a test print on paper or acetate on every new setup, since it only takes a couple of minutes and catches mistakes before a shirt gets wasted.
Honestly, registration is where patience pays off. A colour that's off by a hair is easy to see on a finished shirt.
Step 7: Ink and squeegee
With the garment loaded on the platen, ink goes on the screen. The printer floods the screen, spreading a thin layer of ink over the design, then pulls the squeegee across with firm, even pressure to push ink through the open mesh.
Squeegee choice changes the print. Systematic Automation, a press manufacturer, explains that a softer blade pushes more ink through, while a harder blade gives finer detail. Mesh count plays a role as well. Lawson Screen Products lists low mesh counts for things like metallic and athletic prints, and much higher counts for simulated and four-colour process work.
Step 8: Flash and cure
Many shirt inks, including plastisol, won't dry at room temperature. According to Lawson, plastisol gels, or becomes dry to the touch, between 180 and 250°F, and fully cures between 280 and 320°F.
For multi-colour prints, a quick flash between colours gels the layer just enough that the next screen doesn't smear it. Lawson notes this partial cure usually takes 5 to 10 seconds.
After the last colour, the whole print gets a full cure, usually through a conveyor dryer. ScreenPrinting.com notes that standard plastisol cures at 320°F, low-cure versions at lower temperatures, and water-based inks need airflow as well as heat so the moisture can evaporate. Always follow the ink maker's numbers, because they vary.
Step 9: Quality checks and folding
A print that looks fine coming out of the dryer can still be under-cured. The common checks:
- Stretch test: gently stretch the cooled print. ScreenPrinting.com says cracking ink means it wasn't completely cured.
- Wash test: the more reliable check. The same source recommends at least three wash-dry cycles.
- Temperature checks: laser temperature guns and contact probes help check that the ink actually reached its cure temperature. ScreenPrinting.com points out they measure differently, so know which one you're reading.
- Visual check: look for registration, coverage, stray ink and specks from pinholes.
Then the shirts get counted, sorted by size and folded, ready to go out the door.
What this means for your order
All that setup is why screen printing makes the most sense in batches, and why we have a 10 garment minimum. The screens take the same work whether you print ten shirts or a hundred.
We print up to four colours per design, and our screens go up to 23 x 31 inches. Design help is included, and you'll get a full quote before anything is printed. Timing depends on order size and the time of year, and we'll confirm it in your quote.
Questions people ask
Why does each colour need its own screen?
Each screen only has openings where one colour goes. Separate screens keep colours crisp and let the printer control each one.
Can screens be reused?
Yes. After a job, screens are cleaned and the stencil is removed so the mesh can be coated again. Grimco's guide covers this reclaiming step.
Why does the ink need heat?
Plastisol doesn't air dry. It needs to reach its cure temperature to bond and hold up in the wash.
Got a design you want on shirts? Head to our screen printing page for details and a quote.
Sources
- FESPA: Screen separations in printing
- Chromaline: A Beginner's Guide to Making Screens for Screen Printing
- Grimco: Screen Coating and Exposure Prep Process for Screen Print Shops
- Printable Press: How to Register Multi-Color Screens
- Systematic Automation: Screen Printing Squeegee Tips and Information
- Lawson Screen Products: General Information about Screen Printing Plastisol Inks
- ScreenPrinting.com: Best Practices to Ensure Proper Ink Curing
Written by XUSI, an Indigenous-owned clothing and screen printing brand from Saskatoon on Treaty 6 territory. Our story · What the words mean