Thermographic printing refers to two types of
printing
Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ea ...
, both of which rely on heat to create the letters or images on a sheet of paper.
The simplest type of thermography is where the paper has been coated with a material that changes colour on heating. This is called
thermal printing
Thermal printing (or direct thermal printing) is a digital printing process which produces a printed image by passing paper with a thermochromic coating, commonly known as thermal paper, over a print head consisting of tiny electrically heated ...
and was used in older model
fax machine
Fax (short for facsimile), sometimes called telecopying or telefax (the latter short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer o ...
s and is used in most
shop till receipt
A receipt (also known as a packing list, packing slip, packaging slip, (delivery) docket, shipping list, delivery list, bill of the parcel, manifest, or customer receipt) is a document acknowledging that a person has received money or propert ...
printers. This is called direct thermal.
More complex is
thermal transfer printing
Thermal-transfer printing is a digital printing method in which material is applied to paper (or some other material) by melting a coating of ribbon so that it stays glued to the material on which the print is applied. It contrasts with direct the ...
that melts print off a ribbon and onto the sheet of paper.
Thermography as raised print process
Thermography is also the name of a post print process that is achieved today using traditional printing methods coupled with thermography machines. Thermography machines consist of three sections with a through conveyor.
The first section applies thermographic/embossing powder, made from plastic resins, to the substrate (normally paper). The areas selected for raised printing are printed with slow-drying inks that do not contain dryers or hardeners so that they remain wet during the application of powder. This ink is dried and hardened later during the heating process.
The second section of the process is a vacuum system that removes excess powder from areas of the sheet that were not printed.
The third section of the process conveys the product through a radiant oven where it is exposed to temperatures of 900 to 1300º
F (500-700º
C).
[John McTigue (2005)]
THERMOGRAPHY UPDATE: THERMOGRAPHY OFFERS EXPANDED OPTIONS FOR PRINTERS WITH IMPROVED LASER-SAFE TECHNOLOGY
Worldwide Printing Thermographers Association The heating process takes on the order of 2.5 to 3 seconds. The substrate (usually paper) has a peak in IR absorption at the wavelength used. Through conduction from the paper, the powder temperature rapidly increases and starts melting. When the process is correctly adjusted, the center of the largest filmed areas reach sufficient quality level as the product exits the heater. The melted ink then solidifies as the product cools.
This process is sometimes produced using manual powdering. The substrate with the wet ink is dipped into the powdered polymer. The sheet is then tilted back and forth, rolling the powder across the image. The excess powder is then removed by raising the substrate to a vertical position and lightly tapping the back side. The powdered sheet is then fed into a radiant heating system (as above) at a speed that achieves a good-quality melted film. In the case of craft applications, the powder is melted using a heatgun that blows hot air.
It is commonly used on wedding invitations, letterheads, business cards, greetings cards, gift wrap, packaging, etc... It is sometimes used in
diploma printing as a low-cost alternative to engraved
embossing.
See also
*
Dye sublimation
Dye-Sublimation Printing (or dye-sub printing) is a digital computer printing technique that uses heat to transfer dye onto materials such as plastic, card, paper, or fabric. The sublimation name was first applied because the dye was considere ...
*
List of stationery topics
This is a list of stationery topics. Stationery has historically pertained to a wide gamut of materials: paper and office supplies, writing implements, greeting cards, glue, pencil cases and other similar items.
Stationery topics
B
* Binder c ...
References
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External links
Simple instructions for using thermographic powders for card making
Examples of using raised print or thermography printing on business stationeryVideo demonstrating thermographic printing Non-impact printing