pH is a scale which indicates the relative Acid or Alkaline (Base) of a paper.
0 through 6.9 indicates acid in the paper (the lower the number, the more acid).
A reading of 7.0 indicates “Neutral pH”, meaning the paper is neither acid nor
alkaline. Numbers above 7.0 indicate that the paper is alkaline. Slightly
alkaline is generally preferred to any acidity, especially for printmaking, but
pH Neutral should be the choice.

America Society for Testing and Materials Standards:
Type I: 5.5 pH has a life expectancy for 50 to 100 years
Type II: 6.5 pH – 100 to 200 years
Type III: 7.5 pH – should endure unchanged for over 200 years;
considered archival quality.

These standards are based on proper care being given on the paper during storage,
use and display, which includes framing quality and display area environment.

ACID FREE – Aluminum Sulphate, often used in the paper making process, yields sulphuric acid. This causes paper to discolor, become brittle and deteriorate, finally crumbling. Some papers may contain acid, and still state they are pH Neutral, (expressed as NpH). To do this, an alkaline buffer, such as calcium carbonate, is added to neutralize the acid. While buffered papers are not acid free, they are preferred to papers that give an acid pH reading. Buffering tends to wear off, returning the paper to its acid state. Artists’ papers should be acid free or buffered to counter the effects of environmental acids and pollutants. ALKALINE. A term used when something contains acid or has pH level lower than 7.00 ARCHIVAL. Originally the term "archival" meant that a material or product is permanent, durable or chemically stable and that it can therefore be used safely for preservation purposes. No standards exist that describe how long an "archival" product will last.

100% RAG - In the past, many fine papers were produced from cotton rags collected from hotels, restaurants and consumers, which were then reprocessed into fine papers. Today, with the widespread use of synthetic cloths, it is no longer feasible to produce paper from rags. Today’s “rag” papers are produced directly from cotton. Rag papers are stronger, more attractive and more resistant to discoloration and tearing than non-rag papers.

FUGITIVE OILS & RESINS – In years past, tracing papers and vellums were made transparent by use of oils and resins. Similar to an oil spot on a brown bag. Today, with the use of scanners, copiers and laser printers which produce heat, these fugitive oils and resins can transfer onto expensive equipment, causing extensive damage to the drums (not to mention the odor). Commercial Artists should be careful to avoid these papers.

WEIGHT – The English method to determine the weight of paper was to weigh a ream (500 sheets) of a given size, called “basis” weight. Usually 17” X 22” or 24” X 36” of writing, stationary and many art papers. “Basis” size for Watercolor paper is 22” X 30”. The Metric system, which is rapidly gaining acceptance in the paper industry, provides a better way of specifying paper weight. A square meter (approx. 39.37” X 39.37”) of a single sheet is weighed, and the paper weight is expressed as gm2 and GSM (Grams per Square Meter). This is a more consistent, dependable method of evaluating and comparing paper weights.

RECYCLED – Many recycled papers have never been sold to, nor actually used by any consumer. Recycled scrap might come from waste at the paper mill, roll cutoffs or trim from paper converters or printing and manufacturing waste. Post Consumer Recycled papers include papers that have already been sold to or used by consumers, and are often high in Acid. Ideally, from an environmental standpoint, the purchaser should seek recycled, acid free, paper with a high percentage of Post Consumer Recycled content(about 10-20% PCR).


TRY SOMETHING NEW
Explore different types of paper available for subjects, techniques and styles. Major paper mills such as Whatman, Schutt’s “old Dutch”, Lana’s “Lanaquarelle”, St. Cuthbert’s various brands, LaRocque, Arches, Fabriano and others are all excellent papers of equal quality, each made differently. By diversifying and trying various brands, weights and finishes, you can explore various creative venues and discover which papers are best suited to different subjects, techniques, effects and styles. (hopefully this all works)