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The name of the fiber from a species of banana that originated in the Philippines, but is now grown throughout the tropics for its fiber. It is also known as Manila hemp.
A lignin free paper produced with pH of 7 or higher, with no acid producing chemicals or residues, that also contains an alkali reserve of at least 2%. This is an unregulated term and caution should be exercised when purchasing or using products labelled as “acid free”.
Paper made with the sheet drying by contact with air, either normal or heated, as opposed to by drying with heated rollers.
A light weight paper, pre-folded and with three gummed sections for sealing, usually between 20 and 40gsm.
Papermaking at a pH of 7 or higher is referred to as alkaline papermaking. Due to the use of calcium carbonate as a filler, alkaline papermaking usually has a pH of 8-8.4. Both the soda and the sulphate processes are forms of alkaline papermaking.
An alkaline calcium carbonate reserve in the pulp that acts to neutralize acidity and lengthen the life of the paper. The minimum calcium carbonate reserve is 2%.
An alkaline pH internal sizing in paper and alkaline fillers that mean that the sheet is above pH 7 when formed. Common alkaline sizes are Alkyl Ketene Dimer (AKD), and Alkenyl Succinic Anhydride (ASA). Alkaline sizing enables better archival properties in the paper.
Alkenyl succinic anhydride
Alkenyl succinic anhydride (ASA) is a widely used neutral/alkali internal sizing agent. It was first developed in 1974, and its usage became widespread in the 1980’s. It is a waxy emulsion composed of a linear chain of five member anyhydride ring. It is dispersed and retained to the sheet with the aid of a cationic starch or other type of cationic stabilizer. It has become widely used with the spread of alkali calcium carbonate filler which is unstable in acidic papermaking systems.
Alkyl ketene dimer
Alkyl Ketene Dimer (AKD), first developed in 1956, is one of the most widely used internal neutral/alkaline sizing agents. It is a waxy unstructured lactones emulsion with waxy solid sizes of 0.5-2mm that is dispersed into water. AKD is retained, and stabilized into the sheet with a cationic starch or other type of cationic stabilizer. It has become widely used with the spread of alkali calcium carbonate filler which is unstable in acidic papermaking systems.
In papermaking two chemicals, both called Alum, have been used in conjunction with gelatine or rosin for paper sizing. Alum is also to control the pH, improve retention and bonding of fillers and pigment. Aluminium potassium sulphate was the earliest used alum, and was used as a paper sizing agent from the 16th century. It is thought that alum was first used to slow down the mould growth in gelatine, and only later its sizing properties were noticed. There is a reference to the use of alum in Germany in 1579. Alum could become contaminated by iron compounds, but could be freed of these through repeated recrystallization. Aluminium sulphate started to be used in 1876. This type of alum could not be so easily purified of contaminants, so it often contained iron, silica and sulphurous contamination. In the nineteenth century 1 part rosin to 1.5 parts alum were used to size paper
The portion of cellulose with the highest molecular weight, which is considered to be the purest cellulose. It is insoluble in a 9.5% solution of sodium hydroxide after being swollen in a 17.5% solution of sodium hydroxide. It is found in pulp and paper made from cotton and chemical pulp.
A laid paper made prior to 1800 in which there is a slight shadowing around the chain lines visible with transmitted light.
A class of especially long lasting acid free paper. For paper to be classed as archival it should have passed testing to the standard of ISO11108. Conservation grade archival paper is acid free chemically treated wood pulp, while archival grade or museum grade are made from a rag based pulp, or have a high rag content.
The fibre produced from sugar cane as the waste product of sugar production.
A high quality writing paper, made with chemical and/or rag pulp, with similar working properties to Bond paper but lighter, less than 50 gsm.
A system used in the USA to express the weight of a particular standardized size for a particular type of paper in pounds for a 500 sheet ream. The standardized size for particular paper type is known as the Basic Size. The rest of the world measures a papers weight in grams per square metre; GSM or g/m2
The fibres from the inner bark or phloem of a plant. Plants whose bast fibres are used include kozo (paper mulberry), gampi, mitsumata, flax, hemp and jute.
A machine to fibrillate, break apart and disperse the fibres in the pulp. It consists of a revolving roller, and a bedplate. The fibre source and water are either fed through a pump in a premixed form, or the fibre and water are slowly added separately with the proportions monitored so that the machine can still operate smoothly. Dyes, fillers and sizing can be added to the beater to disperse them through the pulp. Hollander beater is another name for a beater. A naginata beater is a Japanese designed beater that uses slightly curved dull blades to beat through the pulp, rather than a dull bladed roller.
Another name for internally sized. A beater sized paper has had the sizing agent mixed into the pulp
An unsized paper used for absorbing liquid. It is made of rag or chemical pulp or a combination of fibre types.
A high quality writing or printing paper with a weight greater than 50gsm. Originally it had cotton content, however today it may be a machine pulp paper. Important characteristics of this paper are finish, printability, erasability, strength and freedom from fuzz. It is now used for letterhead and stationery and printing. Its name originally came from being the type of paper on which legal documents or government bonds were issued.
Book paper is paper produced specifically for usage in books. Book paper is noted as being opaque, not high white, and frequently between 60 and 90gsm. The caliper thickness to gsm ratio is measured as this can calculate the number of printed pages per inch. A range of paper types and pulps can be used to make book paper.
A chemical process to decrease colour and increase whiteness of the pulp. From 1804 calcium hypochlorite was used as bleach; in the first half of the twentieth century a multistage bleaching process was developed using hypochlorite bleach and an alkaline extraction. In the 1960s and 1970s oxygen bleaching was developed and started to be used. The environmental damage caused by chlorine bleaching became an issue through the 1970s and 1980s, and led to the adoption of Elemental Chlorine Free (ECF) and Total Chlorine Free (TCF) bleaching throughout the 1990s. ECF often uses chlorine dioxide bleaching, sometimes with a small amount of hydrogen peroxide, and alkali washes. TCF bleaching uses peroxide and ozone for bleaching. Many contemporary bleaching processes, such as oxygen bleaching, include delignification.
The short hand way of describing bleaching process when used in sequence:
– C: Elemental chlorine bleaching with chlorine gas
– E: Extraction with sodium hydroxide
– H: Hypochlorite (either sodium or calcium)
– D: Chlorine Dioxide bleaching
– P: Hydrogen peroxide
– O: Oxygen bleaching
– N: Nitrogen dioxide
– Z: Ozone bleaching
Brightness is a measure of the percentage of light reflected by a sheet of paper. There are two standard measures of brightness: TAPPI and ISO.
A paperboard that is uncoated, machine finished on both sides in either plate or vellum finish, and with a weight of between 220 and 250gsm. It can come in a number of different ply with two and three ply the most common, and can be used for a wide range of uses, from drawing, paperback book covers, folders, tickets and tags.
Buffering is the inclusion of an alkaline reserve to slow acid hydrolysis of the cellulose.
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