What is the difference Between Light and Dark Heat Transfer Paper?

The heat transfer paper is intended for use on garments or other substrates with cotton, cotton blend fabrics, or synthetic fabrics as polyester, nylon, and Lycra. Transfer paper can permanently transfer onto these substrates, thanks to the polymer film that bonds the ink and fabric together. It is available in the standard U.S. letter and tabloid sizes of 8.5" x 11" and 11" x 17", respectively. As mentioned earlier, using heat transfer paper allows you to print full-color images on a single sheet of paper. Which means no more layering, for those used to using HTV. Some papers can transfer with no visible background or white space. For most we recommend to either cut paper transfers by hand or use the contour cutting feature of a vinyl cutter (sometimes called "Print & Cut).

Light heat transfer paper is designed for pressing on white or lightly-colored fabrics, while dark transfer paper is for pressing on black or darkly-colored fabrics. Considering that most printers do not have white ink, light heat transfer paper uses the white or light color of the fabric to fill in the white portions of the graphic. Dark transfer paper prints like normal paper, using the white of the paper itself to fill in those spaces, which is why some are called "opaque". Due to the way light transfer paper is transferred, images must always be mirrored before printing them. This will not be necessary for dark/opaque heat transfer paper.