Hahnemühle Photo Rag Pearl 320gsm

Described simple, papers are constructed in two main ways:

Resin Coated papers are the 'modern' approach. These use less fibre and replace the fibre with resin (a nice name for plastic). This means these papers are relatively cheap, strong and robust, but tend to be less attractive to the touch, and accept less ink. They tend to have a clinical appearance and it's hard to write on the back of them. They tend to be popular in the consumer and wedding/portrait markets. Important to note: these papers are difficult or impossible to recycle because of their plastic content.

Fibre Based papers are traditional papers made without plastic, using only plant fibres. These tend to accept more ink and have a more attractive appearance, and these are the papers most of our customers favour. These papers are fully recyclable and we thus strongly recommend you use fibre based papers whenever possible.

What is the paper base made from?

Possibilities include:

• Wood Pulp - the most common and cheapest
• Alpha Cellulose - the best part of wood pulp, separated. Generally tested as archival as cotton etc
• Cotton - the most common fine art paper fibre
• Bamboo - an ecologically friendly alternative to cotton
• Mulberry & more - many other plant fibres can be used to make archival paper

Is this paper acid free?

Acid in paper leads to earlier yellowing and the paper will also become brittle more quickly. Thus for a paper to be archival, it needs to be acid free.

Papers which are not acid free are generally best used for proofing (test printing), and shorter term purposes. That is, they are not considered to be a fine art level product, or suitable for print sales into the art or professional photography markets.

This does not, of course, mean these papers will vanish or discolour overnight - they generally still have life-spans suitable for commercial work and above or on par with e.g. typical photo chemistry papers. They are thus suitable to markets like signage, or the decor market (e.g. print sales for kiddies bedrooms, for example) - but should be avoided if you're trying to sell your work as a serious art level product.

In general, papers made from cotton are naturally acid free, which is one reason they are often favoured. Other fibres, like Kozo, are also naturally acid free. High grade wood pulp papers can also be made to be acid free, however, if the lignin/acid is removed from the pulp.

These days almost all papers are microporous coated - meaning they'll accept inks from both dye based and pigment printers well.

In years past, some papers had a swellable coating - designed to give a greater life to prints with dye based inks but this approach has fallen out of favour.

In 'gsm' - grams per square metre.

Not, technically, the same as paper thickness, but obviously correlated. The heft of the paper. European art papers are traditionally generally around the 300gsm mark. Asian papers historically tended to be lighter, 100 to 200 gsm.

Papers with a higher GSM tend to have more opacity, i.e. you see less through them.

The thickness of the paper, as supplied by the manufacturer. Also known as Caliper (as calipers are used to measure this value).

Unit are in millimetres (e.g. 0.5mm, half a millimetre), or microns/μm = micrometre, or thousands of a millimetre. I.e. 500 microns (μm) = 0.5mm.

(Note in many ways this a much more relevant figure than the more often quoated gsm - as it is thickness of a paper, more than weight, which determines how easily a printer feeds a paper).