Electrophotography

Overview Object View Surface View Magnification Variations

Electrophotography Surface View

Surface Sheen 
Prints can be made on uncoated or coated paper. Uncoated paper tends to be relatively matte. Coated papers, particularly cast coated papers, are commonly used in digital presses and can be used in desktop and office printers. Cast coating is a process in which a white pigment suspended in a binder is applied in a liquid state to the paper support. The coated paper is passed under a highly polished, heated chromium drum. The coating takes on the smooth characteristics of the drum, resulting in a glossy surface.  A textured drum may be used to impart a texture into the coating, resulting in a semi-gloss or semi-matte sheen. 

Dry toner color electrophotographic prints have a slight image relief which is seen as differential gloss due to the build up of toner and the difference in surface sheen of the support and toner. This also occurs on dry toner black and white prints, but is less apparent.  Liquid toner prints have some differential gloss, but less than dry toner, because the liquid toner is thinner when it is applied to the paper and has smaller toner particles. Surface coatings applied as a finishing technique to prints made with digital presses can alter the sheen by diminishing the differential gloss.
These prints all exhibit differential gloss to varying degrees. They were all made using different EP printers including digital presses, office printers, and desktop printers.

These prints all exhibit differential gloss to varying degrees. They were all made using different EP printers including digital presses, office printers, and desktop printers.

This textured paper has a matte surface sheen.

This textured paper has a matte surface sheen.

These prints were all made on coated paper, which gives the print vary degrees of surface sheen.

These prints were all made on coated paper, which gives the print vary degrees of surface sheen.

This print made by a digital press was coated after printing in order to protect the print from abrasion and to give uniform gloss. However, the coating was applied unevenly.

This print made by a digital press was coated after printing in order to protect the print from abrasion and to give uniform gloss. However, the coating was applied unevenly.

Surface Texture 
Dry toner electrophotographic prints have a slight image relief, which is seen as differential gloss. Uncoated papers will bear the texture of the paper fibers. Cast coated papers typically have a smooth texture; a texture may be embossed into the coating during manufacturing. 
Uncoated papers have the texture of the paper support.

Uncoated papers have the texture of the paper support.

The same image was printed on three different papers, each with a different surface texture.

The same image was printed on three different papers, each with a different surface texture.

Fluorescence 
Prints may fluoresce blue under ultraviolet radiation due to the presence of optical brightening agents (OBAs) in the paper support. OBAs are used to create a whitening effect that makes paper appear less yellow by increasing the amount of blue light it reflects. Security code consisting of small yellow dots are the product of an anti-counterfeiting feature built into most eletrophotographic printers. The dots are best seen with UV light, under which they appear as a repeating dot pattern. 
Many EP prints have a security code best seen with UV light.

Many EP prints have a security code best seen with UV light.

Many EP prints have a security code best seen with UV light.

Many EP prints have a security code best seen with UV light.