What is Print on Demand?
Print-on-demand (or simply "POD") is where you sell an item first, then produce or print it only after a customer has placed an order. This is the opposite of the traditional order fulfillment method, where a factory makes the items in bulk first, then sell them to customers afterwards.
There are many types of items that are compatible with POD, including books, mobile phone cases, posters, canvases, stickers and even jewelry, but in this article we're going to focus on the largest and most popular print-on-demand item category: T-shirts.
But first, let's talk about how T-shirts were printed before print-on-demand became popular.
Screen Printing: The Traditional Way to Print a T-Shirt
In screen printing, a patterned mesh screen is used to transfer ink onto a shirt. In this technique, a blank shirt is put on a platen and the mesh screen is laid on top of it. Ink is added to top of the screen, then the screen printer moves a squeegee across the screen to push the ink through the patterned mesh onto the shirt. Historically, silk was used as the material for the screen, so this method is also often called "silkscreening."
A single screen can be used to print the same design on many T-shirts. For images with multiple colors, multiple screens must be used (with each screen created to correspond with the pattern of a single color in that design). It's common to hear, for example, "a two-color screen printing job" to refer to a printing run of an image that contains two distinct colors. Indeed, screen printing costs are determined by the number of colors in the design as well as the quantity of the shirts.
Screen printing is an age-old technique and has its origins in the Song Dynasty (960 to 1279 AD) in China. It did not, however, become a popular way to decorate garments until the 1960s, when an inventor named Michael Vasilantone created a dual rotary printing press that made screen printing T-shirts quick, reliable and economical.
Screen printing was the only way to reliably print on T-shirt for decades until the late 90s, when a new printing technique called direct-to-garment (DTG) printing was invented.
Direct-to-Garment (DTG) Printing
In 1996, Matthew Rhome created a new machine called the direct-to-garment printer, which was basically an industrial-sized ink jet printer that applied ink directly onto garment (hence the name).
The first direct-to-garment printers were slow and finicky, but the printing hardware technology and ink chemistry improved at a rapid pace. In late 2004, printing companies Mimaki, U.S. Screen and Kornit introduced commercially viable DTG printers. Shortly afterwards in early 2005, traditional printing company Brother (known for its consumer inkjet and laser printers) joined the rush and released the first industrial DTG printer built from the ground up with print head and electronics, as well as ink chemistry specifically designed for direct-to-garment printing.
In DTG printing, a digital artwork is converted into a printer-specific printing file through a raster image processor (RIP) software. The print file is sent to the printer, and after a blank T-shirt is loaded onto the machine's printing platen, printing commences. The DTG printer's printheads apply white and/or CMYK ink in specific patterns while the printing platen moves the shirt. After the printing is done, the shirt is offloaded from the platen and the ink is cured under an industrial heat press or in a conveyor dryer.
Since its introduction, the market for DTG-printed shirts have increased with a compound annual growth rate of 10%. As of 2021, the market for DTG in north America is valued to be $2.5 billion. About 1 in every 10 printed T-shirts is currently printed with direct-to-garment method.
The popularity of DTG makes it so that the term "print-on-demand" and "direct-to-garment" is almost synonymous in the mind of customers and suppliers. In many print shop and vendor websites, DTG is the method behind POD on garments(1).
(1)A note on other methods: Although popular, DTG is not the only
print-on-demand method for printing garments. For example, there is dye sublimation, where solid dyes are transferred onto cloth with the use of heat and pressure. There's also heat transfer vinyl or HTV, where a solid sheet of colored or patterned vinyl is cut in a specific shape and then "glued" to the shirt by pressing it on a heat press. While sublimation and HTV are significant players in the POD field, their usages are limited as sublimation requires polyester fabric and HTV are labor-intensive and can only produce relatively simple designs.
There's always new printing methods like Direct-to-Film (DTF) being invented, so it'll be interesting to see how POD continue to evolve.
The Main Advantage of Print on Demand with DTG
Like we've mentioned before, before the invention of POD with DTG, practically all printed shirts were screen printed so it's natural to talk about the pros and cons of direct-to-garment printing as compared to screen printing.
Screen printing is fast, reliable, and economical ... but it has one big drawback: it requires an extensive set-up, so it's not suitable for printing low quantities of shirts (never mind just one shirt).
To screen print a shirt, first we have to create screens containing the design. This is usually called "burning a screen" and it involves covering the screen with a photo emulsion and laying it on top of a film positive, with the design stenciled in black print. A UV light bulb is turned on, and the areas not covered by the black printed design will harden. The area covered by the black printed design will not harden, and the emulsion can be washed out - this is the pattern where you can squeegee the ink through onto the shirt.
The number of screens that need to be prepared depends on how many colors are in the design. A simple design with just a single color requires only one screen. A design with two colors will require two screens and so on. As you can see, the prep phase of screen printing can get quite onerous quickly if the design calls for many colors.
Screen printers usually charge a per-shirt fee as well as a per-screen setup fee. The more colors present in the design means a higher setup fee. If the screen printer charges $20 to set up a screen, then a four-color design (without underbase ink) would cost 4 x $20 or $80 in setup fee alone (and you haven't even printed a single tee!)
In contrast, there is no set-up in print-on-demand with direct-to-garment printing. Printing a white tee is the simplest: the print operator simply loads the white shirt onto the printer's platen and hits the machine's "print" button.
DTG printing a black or color shirt requires a bit more work. First, a liquid solution called "pretreatment" is sprayed onto the shirt. This is akin to a paint's primer that will let titanium dioxide-based white ink to adhere to the cotton fabric. The pretreated shirt is dried using an industrial heat press, then is loaded onto the printer's platen. Then, the printer operator hits the machine's "print" button.
Without any set-up required, the sequence of printing with direct-to-garment printer is identical for printing a hundred T-shirt with the same design or printing a single shirt. This is the main advantage of POD: you can custom-print a single, a few dozens or even hundreds of T-shirts, each with its own unique design.
Note: in industry parlance, the quantity of shirts determine the type of print job. We call printing small quantities of shirts as a "short run" and large quantity as a "long run." DTG is perfect for short runs, and screen printing is perfect for long runs.
The Main Disadvantage of Print on Demand with DTG
So, as explained above, you can custom-print a single T-shirt using DTG but not (at least not economically) with screen printing. But if you're printing thousands, hundreds, or even dozens of T-shirts, all with the same design, it turns out that screen printing is the cheaper option.
Direct-to-garment printing has a fixed per-print cost. It costs the same amount of money (in forms of ink and blank T-shirt) whether you print one shirt or multiple tees.
The per-shirt cost in printing with direct-to-garment is significantly higher than the per-shirt cost of screen print. This is because the white and CMYK ink of DTG printer is the highest cost factor in direct-to-garment printing (not the blank tee). In contrast, plastisol, discharge and water-based screen print inks are cheap.
When printing a small number of T-shirts with screen printing, especially designs with a lot of colors, the screen setup fee accounts for the majority of the cost. With print-on-demand with direct-to-garment print, the per-shirt cost is higher but there's no setup fee so the total cost is lower.
At a certain quantity of shirts, the situation is flipped: the screen setup fee in screen printing is small on a per shirt basis if you're printing dozens or hundreds of shirts, so the total cost can be lower. In contrast, the per-shirt cost of DTG remains constant ... and the total cost is higher.
Other Advantages of Print on Demand with DTG
There are other advantages of direct-to-garment method. Let's talk about them below:
Practically Unlimited Colors
Traditional screen print use one screen per color, so screen printed designs are typically limited to four- to six-colors or fewer. DTG printers, on the other hand, are like giant industrial inkjet printers that print with CMYK ink. They can print thousands of colors in the design (like in color photographs, for example) with ease.
Note: There are screen printing techniques called "simulated process" and "4-color process" that achieve similar results to DTG prints, but these methods are technically difficult and require higher minimum T-shirt quantity to make them worthwhile. Most screen printers don't do them.
Easy Artwork Prep
The colors in the artwork for screen printing need to be in separate layers. Each of those layer corresponds to one distinct color to be burned in a single screen. Because of this, bitmap artwork will require a lot of processing before it can be screen printed.
In contrast, raster-image-processing (RIP) software for DTG takes bitmap artwork as input and automatically converts it to print files ready to print within seconds.
The Ability to Print Intricate Details
The printheads of DTG printers can print at amazing resolutions (up to 1200 dpi or dots-per-inch) so it can print fine and intricate details easily.
In contrast, the mesh size of a screen in screen printing is much larger. The higher the mesh size, the tighter its weave, and the higher the details of the print but the more difficult to push ink through it.
The most popular mesh size in screen printing is 160. This translate to a dot resolution of about 100 micron wide - compare that to 20 micron dot of ink of a DTG printer. As you can guess, the smaller the dot size, the more details you can see, so DTG printers have about 5 times the resolution than a typical screen print.
The Preferred Method to Print Color Photographs
Want a color photo on a shirt? The combination of high resolution and unlimited colors discussed above means that DTG is the preferred method to print full-color photographs on garments.
The Ability to Change Design in the Middle of a Print Job
Imagine you've burned four screens only to realize that there's a typo in the design right before you squeegee the ink onto that first screen-printed T-shirt. You'll have to scrap those screens and prepare new ones.
In contrast, with DTG, all you have to do is fix that digital art file, send the corrected version to the printer, and hit "print"!
Believe it or not, this happens more frequently than you'd expect: clients would call and say "Wait! We just discovered a mistake in the final-final-copy of the art that we approved. Could you re-do everything?"
Easy Personalization
With DTG, it's easy to incorporate names or other personalized details into the design. Got a team of 100 people who want their names printed on tees? DTG is the easiest way to do it.
No Setup Means Quick Turnaround
For low quantities of shirts, even at the quantity point where screen printing and direct-to-garment cost about the same, DTG will usually have a quicker turnaround time. This is because there's no setup like in screen printing: no time required to prep the film positive for the design, burn and rinse the screens, and then mount them on the press.
All you got to do with DTG is load the shirt onto the printing platen and press the print button!
Less Waste
Remember that film positive and screen that screen printers use? After printing, screen printers usually throw away the film positive. While they often reuse the screens, they first have to scrub and remove the old emulsion using specialty chemicals that end up as waste products.
DTG printers don't use a lot of chemicals beside ink, so they produce less waste.
No Inventory Risk with Print on Demand with DTG
Like it says on the tin, print on demand means that the T-shirt is printed only after it's ordered. This means that you can list hundreds or even thousands of T-shirt designs for your customers to buy without keeping a single shirt in inventory.
What happens if all none of those shirts sell? Well, nothing. With POD with DTG, you don't have to pay for any inventory upfront.
In contrast, with screen printing, you have to print, stock, and pay for the shirt upfront. And you better guess the correct number of shirts to print in each size. Guess incorrectly and you'll have a lot of leftover inventory of medium shirts while you've run out of the large shirts that your customers want!
Other Disadvantages of Print on Demand with DTG
There are cons of POD with DTG, including:
Limited Garment Options
Direct-to-garment printing works best with cotton fibers. While most T-shirts are 100% cotton garments, this means that certain types of shirts (like moisture-wicking polyester athletic garments, as well as 50% cotton/50% polyester fleece) are not suitable.
Note: Sublimation is the preferred print on demand method for printing on polyester fabric.
Because they need to be loaded onto the DTG printer platen, certain types of garments like button down shirts and polos (with collar and buttons) cannot be easily printed.
While DTG printers can print on long-sleeves, the technical difficulties in pretreating and pressing the sleeves on a heat press, as well as aligning the sleeves on the printing platen mean that most print shops do not offer long-sleeve prints with direct-to-garment method.
Certain fabric dyes also react poorly to the pretreatment used in DTG and cause unwanted staining or discoloration.
Difficulties in Color Matching
DTG prints with CMYK ink, so it can be difficult to match certain colors exactly. If you need a logo printed in a specific shade of red, that can be difficult to achieve with DTG without a lot of trial-and-error prints.
In contrast, screen printers can buy ink that are already color-matched from the factory. Or they can mix the color according to specific formulas that have been worked out by the manufacturer.
Lack of Specialty ink
Want to print glow-in-the-dark or neon colors? You're limited to screen printing - there's no glow-in-the-dark or neon ink in DTG.
Variable Print Quality and Washability
This one is actually not an inherent disadvantage of DTG, but it's worth mentioning because it's common to find badly printed shirts with faded/muted colors that degrade in the wash, and thus it's logical to assume that it's the fault of DTG.
In ecommerce with print-on-demand, the customer typically see a fantastic digital mockup and not photographs of the actual printed shirt. They can't see the print quality firsthand, so large print shops tend to compete on price rather than quality.
As mentioned above, DTG ink is expensive so print shops trying to cut costs will skimp on the ink (or print in low quality "draft" mode). This results in poor color vibrancy and poor image quality as not enough ink coverage can result in images that are semi-transparent.
Print shops that cut corners on quality also often rush their jobs (after all, they focus on quantity not quality), so they don't cure the printed images properly. Partially cured ink doesn't last in the wash - and the image will be significantly degraded after just a wash or two.
This is not a problem with good print shops: their DTG prints have great ink coverage, vibrant colors, and good washability.