Inkjet Papers Glossary

Paper Base or Substrate

Alpha Cellulose Base: High Grade Wood Pulp, made from trees. Usually less expensive and has a sturdier feel than 100% Cotton Rag.
100% Cotton Rag Base: Cotton Fiber, usually higher grade and more expensive. It is considered to be the best paper base for high quality inkjet reproduction.
Polyester: Plastic base, either clear like OHP or translucent like white film.
Resin Coated: Alpha Cellulose based papers encased in plastic polyethylene, usually coated with microporous inkjet receptive emulsion. Generally a more affordable paper, available in glossy, semi-gloss, satin, lustre and pearl surfaces.
Other substrate materials: Some manufacturers are now making inkjet paper base out of more exotic materials, such as Bamboo, Sugar Cane, Kozo (Japanese Mulberry), Gampi, Mitsumata, Hemp, etc.
Baryta: Short for barium sulphate, an inert clay-like material used as a buffering, smoothing agent and natural optical brightener. Typically used in traditional silver-based black and white darkroom papers, this material is now used for its reflective and smoothing properties with inkjet paper bases, usually alpha-cellulose papers.
Optical Brighteners: Dye additives that paper manufactures will include in their papers to make them look whiter and brighter. Optical brighteners will fade over time as their fluorescing property will diminish. Optical brighteners reflect light differently based on the color temperature and type of lighting used. This means that papers with optical brighteners are more susceptible to the effects of metamerism than papers that do not include optical brighteners. Papers with OBAs are often chosen as they achieve the whitest and brightest white points.

Emulsion

Microporous: Most common type of inkjet receptive coating. Also called nanoporous. Designed to absorb ink in a manner that allows the print to come out of the printer dry to the touch. The image will continue to dry for up to 1 hour. Microporous emulsions will continue to absorb chemicals including airborne contaminants for the life of the print, so spraying the print with a sealant is recommended.
Nanoporous: Most common type of inkjet receptive coating. Also called microporous.
Swellable: Type of emulsion that swells around the ink once the ink is laid down on the paper. Not as common because it is only compatible with dye based inkjet printers. This emulsion allows dye based prints to last significantly longer than with microporous emulsions.
Bronzing: A phenomenon that occurs when an image on inkjet paper is viewed from an angle where part of the image seems to disappear or takes on a strange uniformity. It generally is caused when some of the ink is not properly absorbed into the coating and sits on top of the paper. The effect is only visible from an angle. Spraying your print with a protective coating can help eliminate this effect. Bronzing was a prevalent issue with older inkjet printers but newer printers have endeavored to eliminate the problem.
Cast coating: Typically, one side of the paper base is coated with clay, latex or some other material. While still wet, the coated paper is cast against a hot polished metal drum resulting in a mirror-like glossy surface with a rougher texture on the back.
Metamerism: A naturally occurring phenomenon whereby the color of objects, including inkjet prints, will look different under different lighting situations. Different temperatures of the light reflect different color tones.

Thickness / Weight

GSM: Grams per square meter. A standard measure of weight or paper density. This is not a measure of thickness as in Mil.
Mil: Measure of thickness in thousandths of an inch or caliper. Most high quality RC inkjet papers are 10.4 mil. and have the "feel" of photographic paper.
lbs.: refers to the weight of a 500-sheet ream of 17" x 22" paper. Each of these sheets is equivalent to four letter size sheets. Therefore, 500 sheets of standard 20# paper weighs 5 pounds. The higher the paper weight, the thicker the sheet of paper.
Microns: 1/1000th of a millimeter. 1 micron = 0.0393700787 mils and is a measure of thickness.

Surface

Glossy: Highly reflective smooth surface.
Matte: Non reflective surface texture. Either smooth, slight, medium or heavily textured.
Lustre/Luster: Slightly textured surface with medium reflection.
Pearl: Similar to Lustre/Luster
Semi-Gloss: Smooth surface with minimal reflective surface although not flat matte.
Tooth: refers to the amount of texture paper has. Heavily textured paper would have a high degree of tooth. Smooth papers would be described a low tooth papers. Some manufacturers refer to their papers as Cold Press or Hot Press papers.
Cold Press: Papers with some surface texture including slight to rough.
Hot Press: Papers with a very smooth surface texture.

Archival Permanence

Ratings: Organizations test for image fade using accelerated testing scenarios. All of these tests are in controlled laboratory conditions and the actual print life will vary based on storage. At best these rating systems are a guideline and in no way guarantee image permanence.
Light Fastness: The rate at which inks change color or fade as a result of being exposed to UV light, daylight.
Fade resistance: Terminology used to discuss image permanence of inkjet prints. Some factors affecting fading and archival permanence are temperature, humidity, ozone and air pollutants.
Coating Spray: Protective spray, such as Hahnemuhle Print Protective Spray, which seals the microporous inkjet emulsion, preventing it from continuing to absorb chemicals and airborne contaminants. It also offers some protection against smudges, scratches and fingerprints.

FYI

Everything digital essentially has the archival permanence of a sand painting. Whether it is a computer, hard drive, CD/DVD, memory card or even an inkjet print, at some point it is going to fail, fade or completely disappear. There is no definitive testing available to guarantee archival permanence. There are institutes that rate paper and ink combinations for extrapolated age testing against UV light and other factors that we know affect inkjet prints like ozone. Your best chance at archival permanence is using pigment based inks with fine-art papers. Then spray with a protective spray coating and store the prints either in total darkness or at the very least, in a frame, matted away from the glass and not in direct sunlight.

Inks

Giclée: French term meaning "squirt," as in ink squirted on paper. The term was originally applied to fine art prints created on IRIS printers in a process invented in the late 1980s but has since come to mean any high quality inkjet print.
Dye: Dye dissolved in water to make a homogenized liquid. No particles suspended in solution as in pigmented ink systems.
Pigment: Finely ground pigment particles suspended in solution. More resistant to UV light and therefore fade much more slowly than dye based inks.

FYI

Dye based inks cost less to produce, therefore the printers and ink sets are less expensive to purchase. Colors can be brighter than pigment-based printers but the sacrifice is archival permanence.

Printer Profiles & Media Settings

Printer Profile: A file that describes how a specific printer, ink and paper combine to accurately print color to a given standard using a particular media printer setting. Most paper manufacturers provide profiles that can be downloaded from their website and copied to your Adobe Photoshop, Lightroom or Elements Colorsync folder for Mac or Windows/system32/spool/drivers/color folder for PC. Profiles are similar to developing times for film - never exact, but a good starting point for accurate color rendition. The best way to get great color is to create your own custom profile using color management software. (Note: when using a printer profile you must turn off the printer's color controls.)
Media Setting: As in Epson printer settings, the media setting is a menu setting that is chosen for a particular type of paper such as glossy, matte, semi-gloss, fine-art, canvas, etc. This setting in combination with a printer profile creates accurate color in your image.
Photo Black Ink: Newer pigment printers use two different types of ink that are used depending on the paper you are printing. Photo Black is used for RC papers and papers that have a glossy, semi-gloss or other non matte surface where the maximum density of the black depends on this ink. Photo Black ink is usually a mixture of dye and pigment.
Matte Black Ink: Used with most fine-art matte surface papers and is 100% pigment. You can use Photo Black on matte surface papers but you will not achieve a maximum black.