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Embossing
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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.
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Encyclopedia
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.
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.
Notary use
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.
Postage stamps
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.
The use of etching to make an embossing plate
To make the plate, use a variation of traditional etching. To start, brush an acid-resistant coating, or "ground" (a petroleum product) onto a sheet of copper (16 or 18 gauge). When the ground has dried, you can draw image guidelines onto the plate. Then use a metal stylus to remove areas of ground from the plate: those areas will be etched by the acid and will form the raised areas on the embossed paper when you eventually print. Before etching, make sure that the copper sheet has an acid-resistant backing on the other side.
In conceiving the image, keep in mind that the lines of the embossed print can be raised or recessed, or a combination of the two techniques can be used. You can draw directly on the grounded plate with white crayon, such as water-based Caran d’Ache. Or, to transfer a sketch (preferably on tracing paper), use a light-colored transfer paper, such as Saral, or make one by rubbing chalk onto the reverse side of the drawing. Tape the drawing to the plate so that it does not shift while you do the transfer: place the transfer paper under it, powder-side down, and re-draw the image with a hard-lead pencil.
If the guidelines are for a raised-line image, you will need to decide how much metal to expose by repeated passes of the stylus that removes the acid-resistant ground. Conversely, if a line denotes a recessed area, determine how much ground to scrape away on each side of it. Use a broader stylus to clear larger areas. Scrape away ground thoroughly and whisk off the particles with a piece of paper towel. For an alternative ground, experiment with contact paper, which holds up very well during a long etch. Adhere it to the bare plate and draw guidelines with a water-based crayon. Then, as if doing a paper cut, use an X-acto knife to remove the paper from those areas to be etched; then make sure to scrape any adhesive traces from the exposed metal. Etch in acid, such as ferric chloride for about fifteen hours, then clean the ground from the copper plate with mineral spirits, and print the plate on an etching press, using foam rubber to protect the etching blankets. Slightly dampen the paper before printing. Canson pastel papers work well for this process. A number of examples of this process can be found in the bottom three rows of thumbnails here: http://www.randhuebsch.com/prints.html
Embossing in image processing
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.
See also
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