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What Lies Beneath - Digital Transfer Paper

Posted: 11/10/2014

This month, we’re taking a look at decorating using transfers. There is so much to say on this topic, that we have broken up the discussion into two articles. This first one explores the world of digital transfer applications, and the other delves into adhesive transfers. Digital transfer involves printing onto a sheet of transfer paper that is a temporary home for the ink.

When applied to the substrate using a heat press, the ink transfers from the paper to the surface of the product. The manufacturer usually adds a binding agent to the ink, the paper or both, to ensure that the ink bonds/affixes to the surface during the pressing process. The paper itself is then removed and discarded. Digital transfer papers come in three distinctly different types: inkjet, laser and sublimation. Take note: they are not interchangeable

Inkjet Transfer

Most inkjet digital transfer paper has multiple layers of functionality. The top layer provides an ink management function. It’s composed of a micro-porous polymer that receives and encapsulates the ink, preserves the dots that compose the image and wicks off any unwanted adhesion for the ink during heat pressing. The next layer ensures that the ink and binding elements are released from the paper, so that it can be removed and discarded at the end of the production process.

Sawgrass’ ChromaBlast product is a digital inkjet application that enables you to transfer an image onto cotton. This is not a sublimation process. The heat and pressure applied during production creates a cross-link between the cotton, the inks and the paper, which transfers the image into the fibers of the garment. We’ll discuss sublimation’s transfer process in a bit. Since the binding agents in inkjet transfer paper are spread out across the entire area of the paper, a very light gray image of the unprinted areas of the paper can transfer onto the fabric. You may have heard this referred to as a “polymer window.”

With white garments, simple adjustments in heat, time and pressure will prevent it this. But with some colored garments, it may not be possible to eliminate the discoloration. Many decorators opt to trim the transfer paper right up to the edge of the image. This can be done with scissors, but is much easier with an automated cutter. Craft units start at around $300, and industrial units at about $500.

Laser Transfer

The next type of digital transfer paper on the list is laser carrier paper. It looks a lot like inkjet paper, but is quite different once you go below the surface.

Since laser printers generate a lot of heat during printing, getting a good-quality image can be challenging. The heat from the printer can affect the surface of the paper and its ability to transfer properly when pressed. Quality laser transfers used to be nearly impossible to produce. However, recent improvements in print head and paper technology have greatly improved laser transfer challenges.

The nature of laser printing also affects your prints. Laser toner is applied to the top of the transfer paper’s surface, while inkjet printers encapsulate the ink into the paper’s surface. Though binding and release agents are still used in laser transfer papers, the paper is quite different from that used for inkjet applications.

Laser toner also washes differently than does inkjet inks. Depending on the product you’re trying to decorate, you may want to experiment with both laser and inkjet applications to determine which systems and papers are the best fit.

Just like with inkjet transfers, laser transfers can also produce a polymer window. Cutting your transfer to the printed area is one option for avoiding this. There is also a relatively new laser transfer product on the market called “no-weed” paper, which only transfers the toner (image), not the entire surface of the paper. Though it sounds like the ideal solution, no-weed paper doesn’t work well in situations where you’re looking to create photo realism.

Sublimation Transfer

The third category of digital inkjet transfer paper is sublimation. Even though sublimation is traditionally printed with an inkjet printer, the chemical properties of the ink (which is actually a dye) are radically different from pigment and OEM inks. You need transfer paper that is uniquely engineered for the process to successfully decorate with sublimation.

During pressing, sublimation dye physically penetrates, bonds with and recolors polymer fibers/cells from the inside out. Because this is a molecular process, binding agents are not required and the polymer windows are never an issue. Thus, sublimation transfer paper is composed of a polymer management layer combined with a release agent – and no binder.

On the surface, sublimation papers look all pretty much the same. But, different brands have different manufacturing recipes, so it pays to explore the options on the market. Don’t focus on cost. Look for a product that consistently delivers the highest quality images for your substrates.

Now that you know about the main types of digital transfer papers out there, let’s talk about substrates. Each of these processes are appropriate for specific types of substrates. Standard inkjet and laser papers have binding agents that help the ink bond to the surface of the given substrate. They usually work well for cotton and cotton blend fibers, but not necessarily with polyester and rarely for hard-surface products. If you are able to successfully transfer inkjet or laser prints onto polyester, you may not get the color vibrancy or longevity that is desired.

Sublimation will only work with polyester fibers, polymer products or substrates that have a polymer coating applied to them. The dye has to chemically and physically bond with the polymers in order to transfer. Theoretically, using an inkjet paper with sublimation dye might sound like it would work for non-polymer fiber products, but it doesn’t deliver quality results and has a tendency to wash out quickly.