Embossing is the process of creating a three-dimensional image or design in paper and other ductile materials. It is typically accomplished with a combination of heat and pressure on the paper. This is achieved by using a metal die (female) usually made of brass and a counter die (male) that fit together and actually squeeze the fibers of the substrate. This pressure and a combination of heat actually "irons" while raising the level of the image higher than the substrate to make it smooth. In printing this is accomplished on a letterpress. The most common machines are the Kluge Letterpress and the Heidelberg Letterpress. The term "impressing" enables one to distinguish an image lowered into the surface of a material, in distinction to an image raised out of the surface of a material. Both are "embossing" per se. For embossing metal, see repoussé.
The embossing process can be applied to textiles as non-wovens to get better finished products as sanitary napkins, diapers, tissue paper and others. In printing it is used as an accent process and can be used in conjunction with ink called colour register embossing or with no ink called blind embossing. It also can be used with foil stamping which when embossed with foil is known as combination stamping or combo stamping. All of these processes use a die and counter die. Most types of paper and boards can be embossed and there are no restrictions on size.
Embossing involves a separate stage in the production process, after any varnishing and laminating. This process costs as much as printing.
A notary public frequently uses embossing to mark legal papers, either in the form of an adhesive seal, or using a clamp-like embossing device used to certify (a signature on a document, contract, etc.) or cause to become certified through a notary public or bill.
Embossing has been used regularly on postage stamps. Notable early examples include some of the earliest stamps of Italy, Natal, and Switzerland, as well as the early high values of Britain. Modern stamps still sometimes use embossing as a design element.
Rubber stamp embossing is another form of embossing popular in scrapbooking and cardmaking. A rubber stamp is used to apply adhesive (often a slow-drying, sticky ink called pigment ink) to paper in a desired pattern. Embossing powder is dusted onto the paper and then blown away, so that it adheres only to the stamped surface. The powder is then subjected to heat, which causes it to melt and cover the stamped area. When the heat is removed, the liquified powder fuses into a palpable smooth raised surface in the shape of the stamped pattern. Embossing powders are available in transparent, translucent, opaque, metallic, and glitter colors for a variety of artistic effects.
A variation on heat embossing stamped images is triple embossing. An area of paper is covered with pigment ink and embossing powder sprinkled all over it and heated until molten. This is repeated so that there are a minimum of 3 layers of heated powder. While this triple layer of powder is still hot, a rubber stamp can be pressed into it to leave an indented design.
Embossing also refers to an image processing technique which the color at a given location of the filtered image corresponds to rate of color change at that location in the original image. Applying an embossing filter to an image often results in an image resembling a paper or metal embossing of the original image, hence the name.