1 Complete Process Chain
The entire production process of DTF printing can be described as: creating a design and pattern → printing on a film → applying melt adhesive powder → melting and curing the adhesive powder → transferring the pattern using heat → removing the finished product. The following will explain the operation standards and main points of each step in detail.
Step 1: Pattern File Creation and Preprocessing
The step in DTF printing is getting the design files ready. The main tools used in the industry are Adobe Photoshop for bitmap design and Adobe Illustrator for vector graphics. CorelDRAW is also commonly used. It is important to remember that since the pattern is printed on the film first and then transferred to the clothing all design files must be mirrored and flipped horizontally. Otherwise the text and image directions on the product will be reversed.
Raster Image Processor software (RIP) is the tool that connects the design end and the printing equipment. It is responsible for turning the design files into instructions for the printer and doing tasks like automatically generating white ink managing colors accurately and controlling how much ink is used. Popular DTF raster processing software includes Caldera and Cadlink Digital Factory. These tools can precisely control where white ink is used: transparent areas do not get ink, solid color areas get a full white background and semi-transparent areas get some white ink ensuring the pattern looks good and colors are clear.
The standard file format for printing is 32-bit Portable Network Graphics with a transparency channel (PNG). The final size needs to have a resolution of 300 DPI and the lowest acceptable resolution is 150 DPI. The file background must be transparent and white is not allowed or the system will think the white background is part of the pattern and print white areas.
Step 2: Film Pattern Printing
DTF printing uses polyethylene terephthalate film (PET film) as the printing material. This material is strong, resistant to chemicals. Has good stability making it suitable for long-term storage and high-temperature heat transfer. Depending on the peeling method the film comes in three types: tear, cold tear and cold-hot universal. They should be chosen based on what's needed for production.
The printing process follows a set order: color layers are printed first the white ink layer on top. First four-color ink (CMYK) is sprayed to create a color pattern. Then a white ink layer is added. This order is the opposite of the DTG printing process. The reason is that the DTF process requires flipping the film to stick it to the fabric. After flipping the white ink layer is between the color pattern and the fabric creating a background. This keeps the color pattern bright. Prevents it from looking gray or dark on dark fabric. During the printing process the color layers and white ink layers do not need to dry in between. The time between the two layers must be strictly controlled to one minute to ensure the ink sticks well.
Step 3: Hot Melt Adhesive Powder Coating
After the pattern is printed, melt adhesive powder must be evenly spread on the printing surface before the ink dries. The standard adhesive powder is made from polyurethane (TPU). This material offers flexibility, strong adhesion to fabric and resistance to washing. It is a material in the DTF process.
The size of the powder particles affects the feel, adhesion and compatibility with the fabric. Different particle sizes are used for situations:
• Fine powder (0–70μm): The final product feels the softest. It is good for text, thin lines and lightweight fabrics.
• Medium powder (70–170 μm): A size. It balances adhesion, softness and durability. It works well for common clothes like cotton, blended fabrics and sweatshirts.
• Coarse powder (120–240 μm): It has the strength and adhesion. It works best on strong fabrics like denim and canvas but the final feel is harder.
The coating process needs coverage. Then the film is. Gently shaken to remove any extra glue that is not sticking to the ink area. This leaves the needed layer of adhesive reducing waste.
Step 4: Glue Powder Melting and Curing
After the powder is spread a heating device is used to melt and cure the glue. The main equipment is a powder spreading machine with a tunnel dryer or a hot press machine for -pressure preheating.
The temperature and time for curing must match the glue specifications. For polyurethane glue the standard is 100–120°C for 60–90 seconds. This fully. Sets the glue making it stick well to the ink. Melting glue can be cured in 60 seconds at 110°C. Some technology shows that drying at 125°C for 3 minutes gives the transfer adhesion. The cured film can be used away or stored for later. It is good for making items and adjusting orders.
Step 5: High-temperature Hot Press Transfer
Once the DTF transfer film is ready the printed side is placed face down on the fabric. The transfer is done with a hot press. The temperature, pressure and time must be set for the fabric.
Key process settings:
• Temperature: The standard is 160–170°C for fabrics. Pure cotton can handle temperatures but polyester has poor heat resistance. The temperature should be around 127°C (260°F) and the time increased to avoid shine, color shift and fading.
• Pressure: Usually a medium to pressure is used to make sure the glue sticks well to the fabric. Much pressure can flatten the fabric and leave marks, which affects the final product quality.
• Time: For fabrics, 10–15 seconds. For polyester, 20–25 seconds. For fabrics the time can be a bit longer.
Thick fabrics like sweatshirts need pressure to make up for the pressure loss from the thickness. This ensures the transfer pressure is right.
Step 6: Film Peeling and Shaping
After the hot press is done the PET transfer film can be peeled off to get the pattern. The peeling methods are peeling and cold peeling. They must match the film and production needs.
• Hot Peeling: The film is peeled off after the hot press. At temperatures the connection between the printed layer and the film is weak so peeling is fast. The product feels soft. The pattern edges are clear. It is good for patterns and high-quality clothes.. The operator needs some skill. If not done right the pattern can. Fall off.
• Cold Peeling: The film is left to cool for 10–25 seconds before peeling. This process is stable. Has a high success rate. It is good for workers and large production. Dark fabric transfer looks even. Covers well but the product feels a bit harder. The production time is a bit longer.
Step 7: Finished Product Shaping
Once the film is peeled off the DTF transfer process is done. The final product has colors and good stretch. It depends on the nature of the thermoplastic polyurethane glue layer. It is not likely to come off crack or fade after washes. It has resistance to weather and lasts long. This process works for products, including cotton, polyester and mixed fabrics, for T-shirts, sweatshirts and more. It can also be used for canvas bags, sportswear work clothes and other fabric types.
