Papers are predominantly produced as one of two kinds:

• Resin coated papers (RC). These papers make use of fewer fibers and replace fibers with resin (which is just a cute name for “plastic”). This means that these papers tend to be much cheaper, strong and robust, but also tend to be less attractive to the touch and less ink-friendly. They tend to be very popular in consumer markets;
• Papers based on natural fibers. They’re traditional papers, manufactured without plastics, exclusively produced from vegetable fibers. They tend to accept more ink and look much more attractive when correctly printed. They are the paper of choice for the vast majority of our customers.

What is the paper base or substrate? Possibilities include:

• Cellulose pulp – also called wood pulp – is the most common (and cheaper) way to produce paper;
  
  
• Alpha-cellulose – the noblest portion of cellulose pulp. Commonly tested for cotton-like archival characteristics;
  
  
• Cotton – the most common fiber for the production of media for fine art. Read more about this subject in our FAQ;
  
  
• Bamboo, agave, hemp – ecologically better alternatives than cotton. Many other vegetable fibers (e.g. mulberry) can be used to produce paper with archival characteristics using fewer pesticides and much less water.

At Pigmento we tendo to divide paper finish onto six groups and not always according to what a manufacturer advertises.

• Matte (or Matt) – smooth or textured;
• Gloss – semi-gloss, glossy and high gloss;
• Duo (Duplex) – Special papers (such as Photo Rag Duo) that can be printed in full quality on both sides.

Paper “whiteness” may be defined as follows:

• Cool white – a paper with a blue hue (cool tone);
• Bright or Very White – a paper whiter than natural white papers, but without the bluish tint of cool white paper;
• White (or Natural White) – a natural white (not as white as bright white). Most rags fall into this category;
• Warm – a distinctly warmer paper (yellowish tone);
• Perlescent – paper with a warm gray tone (usually found in metallic and pearl finish papers).

OBA is the short form for Optical Brightening Agents. 

OBAs are chemical compounds added to some papers coating. They are used to enhance the appearance of color, whitening the paper by increasing the amount of blue light reflected and, as a result, offsetting natural yellow tones.

Different papers contain different levels of OBAs. You can confirm whether a paper contains optical brightening agents by placing a sheet under UV light. If it shows a purple color then it contains OBAs, the brighter the purple emitted light, the more OBAs are present in the paper.

In a bit more technical terms, an OBA, or optical bleach, is a colorless aniline, which absorbs UV radiation and emits it as visible radiation. The presence of optical bleach on the paper imposes a predominant reflection in the blue region of the spectrum, positively influencing the reproduction of cool colors (greens, blues and derivatives), thus negatively interfering with the reproduction of warm colors.

The weight (or gramature) of a paper is commonly expressed in grams per square meter (gsm).

It is technically not the same thing as paper thickness, but there is an obvious correlation. European fine art papers are generally around the 300gsm mark. Asian papers, historically, tend to be lighter and somewhere between 100 and 200gsm.

Heavy-weight papers (or high-gramature papers) tend to have greater opacity, meaning you will see less through them.