The heat transfer printing method uses heat and pressure to transfer an image or design from a piece of transfer paper to the desired object. Many objects can be printed on using this method, including T-shirts, cups, mouse pads, memo pads, wood and ceramic plates and tiles. The resulting print is difficult to distinguish from a print done by screen printing, according to printing and copying supplier Coastal Business Supplies.
Early heat transfer printing methods in the 1960s involved a cold peel process. The image was printed on a piece of transfer paper and sold by a retail store. The consumer would purchase the transfer paper and iron on the image at home. This method was not successful and the design often would not stick to the garment or object to which the transfer was being applied. The hot split method, where the ink is split between the paper and the object, was developed later to improve upon the cold peel process.
To use the heat transfer method to print onto an object, the design must be printed onto transfer paper first. To obtain the correct look, the design must be printed in reverse. The transfer paper is then applied to the object using heat and pressure. Heat presses typically heat the transfer to 191 degrees Cor 15 to 20 seconds. Iron-on transfers are intended for use at home and require only an iron and a hard surface.
A heat press is the machine used to transfer a design from the transfer paper to the object. Heat presses can heat a transfer up to 218 degrees C and can press between 40 and 80 psi, or pounds per square inch. Transfers done with a heat press are permanently adhered to the object. A home iron is not able to get as hot as a heat press and the amount of pressure applied by a heat press is far greater than what can be achieved at home, so the quality of the transfer from a heat press is greater than that of an iron-on transfer.
There are two types of machines used in commercial heat transfer printing. Platen presses have a flat surface to hold the item being printed and press it against the ink plate. Platen presses are often used for individual pieces or to print on a rigid surface such as wood or tile. Rotary drum machines print fabric continuously, or roll-to-roll. They are also used to print large designs on banners or signs.
There are several different types of images produced for the heat transfer printing process. The most common are supplier, computer and colour copier transfers. Supplier transfers can be purchased from a commercial business from a catalogue. Computer transfers are created using software and printed onto paper in-house. Colour copier transfers are produced in a copier onto special paper. Other images include embroidered appliques and die cut letters.