How Are T-Shirts Printed?
One of my favorite things to do is search through second-hand stores for t-shirts with curious designs and wry sayings. I get to make my personal statement as I walk down the street. T-shirts are to the self-employed what a yellow power tie is to an executive—self-expression.
But how are they produced? I thought about this recently and did some research. Some of the information was new to me. Much of it I already knew. But what surprised me was the large number of printing options. Here are a handful to get you started.
Heat-Transfer Vinyl
For years, most of the t-shirts I saw were produced in a heat press by pressing a transfer sheet with a vinyl applique against the t-shirt fabric. In this method a plotter first cuts out a design in any number of colors from separate sheets of colored vinyl. These pieces are then arranged on the shirt, which is placed on a platen to keep everything in place and the fabric flat. When the top of the heat press comes down onto the shirt and vinyl, the high temperature fuses the vinyl (which is coated with adhesive) to the shirt.
If you run your hand across such a product, you'll feel the raised vinyl in the design. It has a bit of a rough feel. Unlike some of the other methods for t-shirt decoration, the vinyl does not become a part of the fabric. Rather it it sits on top of the fabric to which it has been adhered.
Vinyl transfers are usually durable if properly applied and do not crack or peel even when the garment is washed repeatedly. In fact, the transfer vinyl may outlast the t-shirt.
One of the benefits of using this method of t-shirt decoration is that you can economically produce a very short print run (even one t-shirt). Therefore, it is a good option for adding numbers to shirts (for sports jerseys, for example).
Unfortunately, you can't produce gradients or halftones within the t-shirt art. The process only lends itself to single (or multiple) flat colors.
Screen Printing and Plastisol
Nothing beats the thick ink of screen printing, in my opinion. Screen printed ink has a substantial feel and is durable. The ink sits up on the surface of the t-shirt as well as seeping into the fabric because of its thick body.
Using photo silk screen processes (involving a computer, light-sensitive emulsions, and chemicals), you can create gradients and halftone images. This puts screen printing ahead of heat-transfer vinyl in terms of design flexibility.
However, this is an expensive process. A lot of work has to be done to prepare the screens for the actual printing, so only a long press run can usually justify screen printing. You wouldn't choose this method for one shirt.
That said, you can replicate the traditional (direct) screen printing look with pre-screened plastisol inks applied to transfer sheets. Basically, this is a screen printed image produced on a paper liner, which you then affix to the shirt using a heat press (high temperature combined with high pressure).
One of the benefits of such a process is that you can either buy or produce a number of screen printed transfer sheets and then affix them one at a time to the t-shirts. This gives you the ability to stock fewer blank shirts and print them as needed, choosing the proper sized shirt for the customer (rather than keeping all screen printed t-shirt sizes and all colors in stock).
In addition to traditional 4-color printing, plastisol transfers are good for glitter, foil, puff, and sparkle printing.
The screen printed product is durable. Like transfer vinyl, the screen printed image may even outlast the t-shirt.
Unfortunately, screen printing the transfer sheets takes time since it is usually a subcontracted operation.
Inkjet- and Laser-Printed T-Shirts
You can make these on your inkjet printer or laser printer. Basically you print the image onto a transfer sheet with ink or toner, and then you transfer the image to the shirt using heat (a heat press or in some cases even an iron).
If you turn the shirt inside-out and wash it in cold water the first few times, it should last quite a while. However, such a product is not as durable as screen printed t-shirts or heat-transfer vinyl t-shirts. Nevertheless, it's very easy to produce and transfer the art for the shirt, and every image can be different. This is a great option for a short print run. For a family get-together, for instance, when the t-shirt just needs to last for the one event, this process may be ideal. And compared to the other options, it's cheap and immediate.
Unfortunately, there can be a boxy appearance of the art (an 8.5” x 11” rectangle in the center of the shirt). You can avoid this by cutting the transfer sheet around the printed image to give it an irregular border.
Inkjet- and laser-printed t-shirts also have a plastic-like feel compared to some of the other options.
Dye Sublimation
For the brilliant colors it yields, this has become my favorite option.
Basically, an image is inkjetted onto a paper transfer sheet using special dyes (rather than inks). The press operator then puts the shirt on the platen in the heat press, puts the transfer sheet on top, and closes the heat press. The heat and pressure then turn the printed ink in the transfer paper into a gas that travels into the fibers of the t-shirt and actually becomes part of the shirt. (That is, the ink sublimates directly from a solid to a gas without first becoming a liquid.)
If you look at the transfer sheet prior to the sublimation process, the dye colors won't seem as brilliant as they will after sublimation and transfer into the fabric. The process intensifies the hues and makes them stunning.
In addition, the feel of a dye sublimated product (called its “hand”) is particularly soft, since the image has become a part of the fabric. This also accounts for its durability.
Since this is a digital process, you can make a press run of one copy or a thousand copies. And each one can be different.
Unlike heat-transfer vinyl, this process can achieve stunning gradients and halftones with a very fine level of detail. Even screen printing could not match the fineness of the dye-sub gradient screen due to the thickness of screen printing inks compared to the much thinner dye-sub dies.
Keep in mind, though, that the process lends itself to fabrics with at least a 65 percent polyester content rather than to cotton fabrics. Shirts must also be of light, rather than dark, material. The supplies are also expensive, and the learning curve to operate the equipment is high.
Embroidery
Don't rule this out. It's not a printing method, but it's nevertheless a most elegant and durable option for decorating a t-shirt (or a hat or even a messenger bag, for that matter). Personally, I'd use it for a more formal shirt than a t-shirt, though, like a polo shirt.
Basically the method involves using thread to create the design, usually on a sewing machine run by a computer to automatically sew the logo, pattern, or image into the garment.
What makes this interesting, I think, is the raised, tactile nature of the product. It has even more depth than screen printed ink, so it feels very substantial to the touch.
[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]