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Greaseproof Paper
Greaseproof paper is paper that is impermeable to oil or grease, and is normally used in cooking or food packaging. It is usually produced by refining the paper stock and thus creating a sheet with very low porosity. This is then passed between hard pressure rollers ( supercalendered) to further increase the density, creating a paper called glassine. The glassine is treated with starches, alginates or carboxymethyl cellulose (CMC) in a size press to fill pores or treat the paper chemically to make it fat repellent. Basis weights are usually 30–50 g/m2. See also * Darcy (unit) * Parchment paper * Permeability (earth sciences) * Permeation * Wax paper Waxed paper (also wax paper, waxpaper, or paraffin paper) is paper that has been made moisture-proof and grease-proof through the application of wax. The practice of oiling parchment or paper in order to make it semi-translucent or moisture-pro ... References External links Greaseproof Board {{Paper Paper Food prepar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed on the surface, followed by pressing and drying. Although paper was originally made in single sheets by hand, almost all is now made on large machines—some making reels 10 metres wide, running at 2,000 metres per minute and up to 600,000 tonnes a year. It is a versatile material with many uses, including printing, painting, graphics, signage, design, packaging, decorating, writing, and cleaning. It may also be used as filter paper, wallpaper, book endpaper, conservation paper, laminated worktops, toilet tissue, or currency and security paper, or in a number of industrial and construction processes. The papermaking process developed in east Asia, probably China, at least as early as 105 CE, by the Han court eunuch Cai Lun, although the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porosity
Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of void space accessible from the surface (cf. closed-cell foam). There are many ways to test porosity in a substance or part, such as industrial CT scanning. The term porosity is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, petrophysics, hydrology, earth sciences, soil mechanics, and engineering. Void fraction in two-phase flow In gas-liquid two-phase flow, the void fraction is defined as the fraction of the flow-channel volume that is occupied by the gas phase or, alternatively, as the fraction of the cross-sectional area of the channel that is occupied by the gas phase. Void fraction usually varies from location to location in the flow ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supercalendered
A calender is a series of hard pressure rollers used to finish or smooth a sheet of material such as paper, textiles, rubber, or plastics. Calender rolls are also used to form some types of plastic films and to apply coatings. Some calender rolls are heated or cooled as needed. Calenders are sometimes misspelled ''calendars''. Etymology The word "calender" itself is a derivation of the word κύλινδρος ''kylindros'', the Greek word that is also the source of the word "cylinder". History In eighteenth century China, workers called "calenderers" in the silk- and cotton-cloth trades used heavy rollers to press and finish cloth. In 1836, Edwin M. Chaffee, of the Roxbury India Rubber Company, patented a four-roll calender to make rubber sheet. Chaffee worked with Charles Goodyear with the intention to "produce a sheet of rubber laminated to a fabric base". Calenders were also used for paper and fabrics long before later applications for thermoplastics. With the expansio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glassine
Glassine is a smooth and glossy paper that is air, water, and grease resistant. It is usually available in densities between . It is translucent unless dyes are added to color it or make it opaque. It is manufactured by supercalendering: after pressing and drying, the paper web is passed through a stack of alternating steel- and fiber-covered rolls called a supercalender at the end of the paper machine so that the paper fibers flatten facing in the same direction. Usage Glassine is most commonly used as a base for further silicone coating for manufacture of release liner. Glassine is also employed as an interleaving paper in bookbinding, especially to protect fine illustrations from contact with facing pages; the paper can be manufactured with a neutral pH, and can prevent damage from spilling, exposure, or rubbing. Glassine adhesive tape has been used in book repair. In chemistry, glassine is used as an inexpensive weighing paper. It is used in foodservice as a barrier betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starch
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in staple foods such as wheat, potatoes, maize (corn), rice, and cassava (manioc). Pure starch is a white, tasteless and odorless powder that is insoluble in cold water or alcohol. It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight. Glycogen, the energy reserve of animals, is a more highly branched version of amylopectin. In industry, starch is often converted into sugars, for example by malting. These sugars may be fermented to produce ethanol in the manufacture of beer, whisky and biofuel. In addition, sugars produced from processed starch are used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alginate
Alginic acid, also called algin, is a naturally occurring, edible polysaccharide found in brown algae. It is hydrophilic and forms a viscous gum when hydrated. With metals such as sodium and calcium, its salts are known as alginates. Its colour ranges from white to yellowish-brown. It is sold in filamentous, granular, or powdered forms. It is a significant component of the biofilms produced by the bacterium ''Pseudomonas aeruginosa'', a major pathogen found in the lungs of some people who have cystic fibrosis. The biofilm and ''P. aeruginosa'' have a high resistance to antibiotics, but susceptible to inhibition by macrophages. Structure Alginic acid is a linear copolymer with homopolymeric blocks of (1→4)-linked β-D- mannuronate (M) and α-L- guluronate (G) residues, respectively, covalently linked together in different sequences or blocks. The monomers may appear in homopolymeric blocks of consecutive G-residues (G-blocks), consecutive M-residues (M-blocks) or alterna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxymethyl Cellulose
Carboxymethyl cellulose (CMC) or cellulose gum is a cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone. It is often used as its sodium salt, sodium carboxymethyl cellulose. It used to be marketed under the name Tylose, a registered trademark of SE Tylose. Preparation Carboxymethyl cellulose is synthesized by the alkali-catalyzed reaction of cellulose with chloroacetic acid. The polar (organic acid) carboxyl groups render the cellulose soluble and chemically reactive. Fabrics made of cellulose—e.g. cotton or viscose rayon—may also be converted into CMC. Following the initial reaction, the resultant mixture produces approximately 60% CMC and 40% salts (sodium chloride and sodium glycolate); this product is the so-called technical CMC, which is used in detergents. An additional purification process is used to remove salts to produce pure CMC, which is used for ali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sizing
Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorption and wear characteristics of those materials. Sizing is used for oil-based surface preparation for gilding (sometimes called ''mordant'' in this context). It is used by painters and artists to prepare paper and textile surfaces for some art techniques. Sizing is used in photography to increase the sharpness of a print, to change the glossiness of a print, or for other purposes depending on the type of paper and printing technique. Fibers used in composite materials are treated with various sizing agents to promote adhesion with the matrix material. Sizing is used during paper manufacture to reduce the paper's tendency when dry to absorb liquid, with the goal of allowing inks and paints to remain on the surface of the paper and to dry the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grammage
Grammage and basis weight, in the pulp and paper industry, are the area density of a paper product, that is, its mass per unit of area. Two ways of expressing grammage are commonly used: * Expressed in grams (g) per square meter (g/m2), regardless of its thickness (caliper).International Standard ISO 536: Paper and board – Determination of grammage. International Organization for Standardization, Geneva. This is the measure used in most parts of the world. It is often notated as gsm on paper product labels and spec sheets. * Expressed in terms of the mass per number of sheets of a specific paper size, known as ''basis weight''. The convention used in the United States and a few other countries using US-standard paper sizes is pounds (lb) per a ream of 500 (or in some cases 1000) sheets of a given (raw, still uncut) basis size. Japanese paper is expressed as the weight in kilograms (kg) per 1,000 sheets. Grammage In the metric system, the mass per unit area of all types of pap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Darcy (unit)
The darcy (or darcy unit) and millidarcy (md or mD) are units of permeability, named after Henry Darcy. They are not SI units, but they are widely used in petroleum engineering and geology. The unit has also been used in biophysics and biomechanics, where the flow of fluids such as blood through capillary beds and cerebrospinal fluid through the brain interstitial space is being examined. A darcy has dimensional units of length2. Definition Permeability measures the ability of fluids to flow through rock (or other porous media). The darcy is defined using Darcy's law, which can be written as: :Q = \frac where: : The darcy is referenced to a mixture of unit systems. A medium with a permeability of 1 darcy permits a flow of 1 cm3/s of a fluid with viscosity 1 cP (1 mPa·s) under a pressure gradient of 1 atm/cm acting across an area of 1 cm2. Typical values of permeability range as high as 100,000 darcys for gravel, to less than 0.01 microdarcy for granite. Sand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parchment Paper
Parchment paper, or vegetable parchment, is a cellulose-based composite that has been processed to give it additional properties like non-stickiness, grease resistance, and resistance to humidity. It is commonly used in baking as a disposable non-stick, grease resistant surface. It should not be confused with waxed paper, which is paper that has been coated in wax. Parchmentization of paper Vegetable parchment paper is made by running sheets of paper pulp through a bath of sulfuric acid (a method similar to the way tracing paper is made) or sometimes zinc chloride. This process partially dissolves or gelatinizes the paper. This treatment forms a sulfurized cross-linked material, with high density, stability, heat resistance, grease resistance, water resistance, no loose fibers as well as low surface energy — thereby imparting good non-stick or release properties. The treated paper has an appearance similar to that of parchment and, because of its strength, is sometimes use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
