Before your print shop diversifies into garment printing, you may need to learn more about some pretreatment and finishing equipment that may be required to convert blank T-shirts, sweatshirts, socks, and other apparel into ready-to-ship products.
The type of ancillary equipment you need will depend on whether you plan to use screen, direct-to-garment (DTG), heat-transfer, or dye-sublimation printing to decorate the garments and how you will market the products. For example, garments for sale in brick-and-mortar retail stores may have different finishing requirements that those that will be shipped directly to customers.
Pretreatment fluids are applied to blank garments that will be printed on DTG printers. The fluids help control the appearance and washability of the aqueous pigment inks on cotton and poly/cotton T-shirts and other fabric items. When the pretreatment fluid is heat-dried on the blank garment, the fluid bonds with the fabric. During printing, the chemistry of the pretreatment fluid reacts with DTG printer inks to form a gel that stays on the fabric surface of the fabric.
Pretreating is a must when printing bright colors and photographic images over a white ink underbase on dark garments.
Pretreatment fluids for dark garments keep the white ink from soaking into the fabric, causing all colors to look muddied.
Pretreatment fluids for light garments prevent DTG inks from bleeding on garments made from polyester or poly/cotton blends.
Small shops can use handheld high-pressure spray guns (such as Wagner paint sprayers) to pretreat shirts. But pretreatment spray booths must be set up far enough away from the DTG printer so that the overspray doesn’t affect the printer.
Pretreatment Machines apply controlled amounts of pretreatment fluid to different types and sizes of garments. They can be programmed to apply fluid only to the areas of the garment that will be printed. Pretreatment equipment with enclosed spray chambers can be set up closer to the equipment that will be used to print and dry the garments.
Examples of pretreatment devices include the EZPrep from M&R, the Viper MAXX, and the Lawson Zoom Pro Pre-Treat Sprayer.
Print shops that don’t want to invest in spray booths or pretreatment machines can buy pre-treated, DTG-ready blank garments from suppliers such as RTP Apparel. Or, they can invest in Kornit industrial DTG printers with built-in pretreatment systems.
Pallets are printer accessories designed to hold different sizes and shapes of garments flat and wrinkle-free during pretreating and printing. Different pallets are available for T-shirts, socks, garment sleeves, tote bags, zippered sweatshirts, children’s wear, and other garments.
Before a garment is printed, the pretreatment fluid must be fully dry. Plus, inks on the printed garments must be fully dried before the shirts are folded and bagged.
Conveyor Dryers use moving belts to transport pretreated or printed garments beneath a drying unit that uses either infrared heating or forced air (convection) systems. The amount of time the garment must dwell in the dryer depends on the ink chemistry. Water-based digital-printing inks and discharge screen printing inks require longer dwell times than plastisol screen-printing inks.
Many conveyor dryers are optimized for either DTG printing or screen printing. To save space in shops that use both screen-printing presses and DTG printers, M&R’s Sprint 3000D conveyor system uses two stacked belts to feed garments through two separate heat chambers. In this device, users can simultaneously dry shirts printed with screen-printing plastisol inks and shirts output on DTG printers.
Flash Dryers are free-standing, easy-to-move units that are typically used to partially dry a screen-printing ink so another color can be printed on top of it or adjacent to it. The flash dryer is positioned a few inches above the platen of a screen-printing press and switched on for a few seconds. The flash dryer heats the ink to the point at which it gels and is tacky to the touch.
A heat press uses a combination of heated and non-heated metal flat plates (platens) to apply controlled amounts of heat and pressure to different types of materials used to decorate garments. The amount of time and pressure required depends on the thickness of the garment and whether you are using inkjet transfer paper or dye-sublimation transfer paper or applying digital appliques or cut adhesive-vinyl.
In the DTG printing process, heat presses can cure pretreatment fluids on blank T-shirts before printing and dry the textile inks printed on the shirt.
Clamshell heat presses have platens that are joined by a hinge at the back of the device. After the garment is inserted, the raised upper platen comes together with the lower platen like a clamshell. Some devices have separate controls to heat the bottom platen.
In a swing-away press, the heated top platen can be rotated out of the way so the operator can safely load the next shirt to be dried or decorated.
In a draw heat-press, the operator pulls the lower platen out from under the heated top platen to load and unload garments.
Different types of processes are used to add special decorative effects to custom garments.
Digital Embroidery uses computer-controlled sewing machines to convert digital files into raised letters, logos, or designs. Instead of using ink, embroidery machines different colors of thread to create the designs. Converting designs into ready-to-embroider files is different than preparing digital print files.
Appliques are created by sewing pre-cut pieces of fabric to garment. An applique can be an embroidered patch or simply a decorative patch made with a different fabric color or pattern.
Heat transfers are pre-printed designs that are applied to a garment via a heat press. The designs are screen-printed or digitally printed onto an adhesive-backed transfer media. After a vinyl cutter has trimmed to printed sheet to follow the contours of the printed design, the heat-transfer graphic is positioned on the surface of the garment and placed in a heat press.
When the right amount of heat and pressure is applied, the printed design is transferred to the surface of the garment. The protective liner on the heat-transfer media is then peeled away from the face of the graphic. Heat-transfer printing can be used to add reflective or holographic vinyls or flocked materials to the surface of a garment.
Unlike the dye-sublimation heat-transfer process for infusing sublimation inks into polyester garments, heat transfers can be applied to all colors of garments, including non-polyester garments. Stahls is a leading supplier of heat transfer materials and heat presses equipment for heat transfer printing.
Many print shops serve customers that convert blank garments into branded fashion and licensed team apparel. For these customers, your shop may need to add labels and hang tags to the garment, then fold and bag them for shipment to retailers or customers.
Hang tags are creatively designed to give the buyer more information about the clothing item. Like packaging, a well-designed hang tag is a form of brand marketing. Some print shops specialize in printing, die-cutting, folding, and stringing custom hang tags for apparel products.
Labels can be printed directly inside the back neckline of a T-shirt to indicate the brand, garment size, fiber content, and care instructions. Labels can be screen-printed with compact Rapid-Tag automatic presses or digitally printed onto heat-transfer media and heat-pressed into the garment.
Automatic folding machines provide faster, more uniform folding than paying pressroom employees to fold garments manually. Companies that make screen-printing presses for higher volume garment decoration (such as M&R and Lawson) also offer garment-folding equipment.
Automatic bagging machines insert folded garments into bags and seals the bags. For example, M&R’s AB-9000 machine can bag and seal up to 18 roll-fed bags per minute. It process bag sizes ranging from 4 x 5 inches to 12 x 15 inches. When used in conjunction with M&R’s K-950 automatic folder, a single operator can fold and bag up to 1,000 garments per hour.
To enable more types of companies to add DTG printing, companies such as Lawson and M&R are developing multi-purpose devices that combine multiple garment-finishing processes in one machine.
For example, the Lawson Evolve SDP combines can spray, dry, and press garments printed on DTG equipment. M&R folding devices can be equipped to apply pressure-sensitive labels to folded garments that will be stacked in retail displays.
This series of print-business glossaries is designed to help you understand how different types of printing and finishing processes can be combined to produce a huge variety of products. Follow Ordant on LinkedIn, Facebook, Twitter to learn when the next post in this series is published.
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