The traditional digital sublimation process applies a digital printer to produce an opposite image on a transfer paper, and then transfer the image to the final substrate (which can be polyester or other polyester coating material) by heating. This process usually uses water-soluble, solvent-based, or oil-based sublimation ink, which can be used to expand color gamut of the print.
Thermal sublimation is a process that makes matter change from solid to gaseous state directly, without liquid state. The fogging process of dry ice at room temperature is a typical thermal sublimation process.
The thermal sublimation ink on the transfer paper is transferred to the final substrate by a transfer machine, whose temperature is between 356-410 ° f (180-210 ° C). Under high temperature and high pressure, the dye will turn into gas, penetrate into the fiber, and finally solidify on the textile. When the temperature exceeds 390 ° f (200 ° C), the sublimation ink will immediately become gas. In addition, heating can also make the small holes on the polyester or polyester coated substrate surface open, and let the gaseous dye penetrate into the material. After stopping heating, the ink will cool into a solid, and the holes on the polyester material will close. If operated correctly, the printed image will not fade, crack or age.
The traditional thermal sublimation is to print the image on transfer paper with a digital printer, and then transfer it to the final substrate, while the direct thermal sublimation is to print the image directly on the substrate without transfer paper. Textile fibers used for direct thermal sublimation usually have a special coating that allows the thermal sublimation ink to flow freely. When the textile is heated, the ink will penetrate into the textile fibers through sublimation, thus forming a lasting image.
Direct printing is a cost-effective way of production, and can make ink better penetrate into the textile fiber. However, transfer paper allows users to get better image quality, especially the details and edges of images. Transfer image looks very vivid, because the water absorption of fiber is not as strong as paper. But for flags and other textiles that need to be printed on both sides, direct thermal sublimation is an ideal solution.
Compared with UV and solvent-based ink printing, the biggest advantage of thermal sublimation printing is its wide color gamut. The vitality and high density of heat transfer ink can provide those ad. designers with more choices.
When considering whether using traditional or direct sublimation printing, we must take equipment cost, image saturation and quality, consumables cost (ink and substrate) and labor cost into account. Some printing equipment must use a heat transfer machine, and some has built-in heating device, no need of manual intervention. If you want to carry out traditional thermal sublimation printing, at least one printer and one heat transfer equipment are needed, so that the production cost will multiply with the increase of printing size, but if you want to carry out direct thermal sublimation printing, you can just buy one online or multi-functional system.