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Thermomechanical pulp
This is mechanical pulp that is produced from woodchips that have been heated with steam and then pulped or refined in a pressurized vessel, usually at between 30 to 150psi. The advantages of thermomechanical pulping are greater freeness of pulp, longer fibres, greater tear and burst strength in the paper and the ability to add chemicals, such as calcium chloride, magnesium chloride or sodium bisulphite to the process. It is abbreviated to TMP.

Titanium dioxide
A white pigment that was first developed in 1821, although it was not able to be effectively mass produced until 1916. It was commercially available as an oil paint until 1921. It is used in paper fillers and coatings to increase brightness and opacity. Its chemical formula is TiO2.

Tomlinson recovery boiler
First invented by the Canadian G. Tomlinson in the early 1930s, it is a device for recovering processing chemicals from used, lignin containing chemicals in the Kraft process. The used processing chemicals, called black liquors, contain dissolved organic wood residues, such as resins and lignin, and sodium sulphate used in the cooking in the digester. The recovery boiler combusts the organic material, reduces the inorganic sulphur to sodium sulphide which is then further recycled, production of molten sodium sulphide and sodium carbonate for further recycling and recovery of inorganic dust and sulphur fumes.

A term used to describe the surface smoothness or roughness. Tooth is important in many drawing papers because it assists in holding graphite, crayon or pastel.

Total chlorine free
A bleaching process that uses no chlorine compounds. Chemicals used in total chlorine free bleaching include oxygen, ozone, and hydrogen peroxide. It is abbreviated to TCF.

Tracing paper
A translucent paper with no fillers or loaders. It is created by either using overbeaten cellulose fibre with all of the interfibre oxygen removed, or by filling the interfibre spacing with a material with the same refractive index as the cellulose, or by dipping the formed sheet in sulphuric acid. Paper produced by the last method is sometimes referred to as parchment paper.

Tree free
Tree free pulp or paper is made from non-wood sources; such as agricultural by product, textile or cordage wastage or specific fibre crops such as bamboo, kenaf, hemp or linen.

Tub Sizing
Tub sizing is when the sizing agent is applied to the already formed sheet, and not to the pulp before it is made into a sheet. It is also known as surface sizing.

Twin wire machine
This is a variation on the Fourdrinier machine in which the newly formed sheet is pressed between two wires and guided vertically through dryers and the forming section, thus increasing the drying rate and giving a uniform two sided page. It was first invented in 1884 by Escher Wyss. It is also called a gap former.

Urea-formaldehyde resin
A synthetic resin used to increase the wet strength of papers.

Vatman’s tears
White dots seen on a handmade sheet when viewed against the light. These are caused by drops of water falling onto the still wet sheet, dispersing the fibres and thinning the paper. They are also sometimes called Vatman’s drops or Coucher’s drops.

Vegetable parchment paper
A paper created by passing an unsized rag, or chemical pulp, paper through a bath of sulfuric acid or zinc chloride, and then washing it thoroughly. The acid hydrolyses the cellulose and leaves the paper heat, grease and moisture resistant as well as being more translucent. Paper produced this way is sometimes referred to as parchment paper or vellum paper.

A type of parchment produced from calf skin. It can also mean fine, high quality parchment produced from other animals than calf.

Vellum paper
This term could refer to paper that is a vegetable parchment paper, or a finish of high grade stationery, or a paper produced using one of the methods to make tracing paper.

Waterleaf paper
A paper with no sizing.

An image or text formed in a sheet of paper by the thickness or thinness of the paper pulp. They are usually only visible with transmitted light. Wire, shadow and multi-tonal watermarks are all types of watermarks.

Wet end
In a papermaking machine, the part of the machine consisting of the headbox and the sheet forming section. This term can sometimes include the parts of the pulp process such as the beater, refiner and chest head.

White lead
White pigment traditionally produced by exposing metallic lead to acetic acid. Its chemical formula is 2PbCO3.Pb(OH)2. It was used prior to the 20th century as a coating pigment in various formulations. When exposed to atmospheric hydrogen sulphide it can darken to a black colour.

An endless circular mesh onto which the pulp is flowed to form the paper. They are made of stainless steel, bronze or monofilament fibre woven fabric.

Wire Watermark
This type of watermark is formed by a design made with wire on the paper mould, or on the mesh of the dandy roll. The areas of the paper which have the wire are thinner as the wet pulp slips of the surface of the wire, and so these places of the page appear lighter.

Wood free
Pulp or paper not created from mechanical pulp. As this paper is made from chemical pulp it is more archival as the lignin has been removed.

Wove Paper
A paper with uniform surface, made on a fine mesh, without the visible chain and laid lines found in laid paper. The first wove paper was produced by James Whatman in the 1750s. The invention of the papermaking machine in 1807 led to the easier production of wove paper on a smooth continuous metal mesh.

Zinc oxide
An inorganic pigment used in coating papers. It has the chemical formula ZnO.

Zinc sulphide
A pigment, coating or loading agent with the chemical formula ZnS.


(National Archive of Australia)