ISO 9706 standard for Stamp Album Pages and Storage Products
ISO 9706 standard for Stamp Album Paper
Information and Documentation – Paper for Documents – Requirements for Permanence
|pH||7.5-10.0||All layers of the paper must meet this requirement.|
|Alkaline reserve(calcium carbonate equivalent)||2%|
|Tear resistance||350 mN (CD & MD) for all papers over 70 g/m2||A formula is provided for finding tear resistance value for lighter weight papers.|
|Resistance to oxidation||Kappa number under 5.0||This requirement limits lignin and other material that may oxidize. It takes the place of “Fiber quality” or “No groundwood or unbleached fibers” in other standards.|
Background Information on the Manufacture of Acidic and Alkaline Paper
We distinguish two main periods in the manufacture of paper – and hence – usage with art and stamps. During the first, which continued until the middle of the nineteenth century, the basic material from which paper was made was vegetable in origin (white linen, hemp, cotton). The resulting paper was composed of cellulose, a substance found in plant fibres, a sizing of vegetable or animal glue, and a small reserve of alkali. The water molecules incorporated in the pulp during the process of paper making formed bonds with the hydroxyl radicals of the cellulose, and hence served as a bridge (hydrogen bridge) between contiguous long-chain cellulose molecules.
As demand for paper for production of books and stamps started to grow, it exceed the amount of available white linen, hemp, and cotton rags, a replacement in the form of wood pulp was gradually phased in. Chlorine compounds were introduced as bleaching agents and natural processing products began to be replaced with chemical products, namely alum, which unlike the natural product was added to wood pulp before the formation of the paper. However, chlorine and alum residues from both types of processes caused acidity in the paper. Acidic paper decreases the durability of the paper by causing the breakdown of the constituent molecules into short-chains. Exposure to light, changes in humidity and temperature, and atmospheric pollutants increases the rate that such breakdown occurs. Such results are easily demonstrated by the rapid browning of the paper used for newspapers, which after only a short few days can be seen to start yellowing, and which after a longer period of time become brittle to the touch.
The change in paper manufacture processes in the mid 1800’s leads to a counterintuitive, but beneficial result, whereby many older linen and rag based based stamps and paper products have a higher probability of survival than their later short-chain brethren. An explanation for this effect stems from chemical and environmental interactions that cause the paper molecules to continually be broken down – which in the case of long-chain molecules, take more time to reach the point where short-chain molecules eventually breakdown.
The goal when attempting to preserve paper based articles, including stamps, is to delay this point of breakdown for as long as possible, not eliminate it, which with the present state of the art is impossible. To this end, in the 1950s, a type of paper with an alkaline buffered content began to be manufactured. It is this type of paper that those in the field of art have learned to use to create, store, mount, and mat their collections. Stamp collectors have embraced this usage as well. Alkaline buffered paper is generally thought of as “safe.” When items with an acidic pedigree (eg. stamps) are placed on alkaline buffered paper (eg. stamp album pages), it has been shown that damaging acidic reactions can be greatly reduced, but as discussed elsewhere, not completely eliminated.