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Holographic paper is a sheet of paper that has been embossed with a pattern or image and then coated in a very thin layer of metal. The resulting sheet has a distinctive iridescent sheen where the embossed design can be seen at certain angles. When the holographic paper is viewed from different perspectives, different parts will appear in various colors, creating a rainbow effect with the design still visible. The fields of marketing, security and the arts have all found uses for holographic paper.
The production of holographic paper begins with the design or pattern to be imprinted. The design has to be embossed for the holographic effect to happen. This can be done either before the paper is coated or afterwards and is most commonly done with a regular printing press. Embossing is the process of raising an area of the paper, creating a three-dimensional (3D) design.
For the paper to become holographic, it must be metalized. This is the process that gives the paper its holographic properties. The paper is placed in a machine that creates heat and a vacuum. Metal, usually aluminum, is then heated until it evaporates and rises as a gas. The gas falls on the surface of the paper and coats it in a layer so thin that it is nearly transparent.
The resulting effect is that, when light hits the holographic paper, light is scattered by the metalized coating. In addition to refracting off of the surface, the light that penetrates the coating is refracted between the coating and the paper. This combination of the embossed areas and the scattering of the light that hits the paper is what creates the holographic effect.
Nearly any type of base paper can be coated and embossed to create holographic paper. Anything from thin sheets of newsprint to cardboard or self-adhesive rolls can be used. There is even inkjet paper available for home printing so images can be placed on top of the coating.
There are a number of commercial uses for holographic paper. It has found a wide audience in the advertising and marketing fields. This is where it is applied to displays, product packaging and other promotional materials. The unique and dynamic movement of light across the surface of the paper draws attention to products that are on shelves that might be stocked with hundreds of other items.