>>Log On     
Welcome to the Australian Paper Uncoated Printing Papers Web Site Privacy Policy      
Australian Paper website
   
  Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z - UNITS
 
 

A

Acid Free

A term describing paper and board that can be used with anything that may be tarnished or otherwise harmed by acid.

Alkaline Pulping
A general term, but usually applied to the kraft or soda process as in contrast to the acid sulphite process.


Alkaline Sizing

Internal sizing under alkaline stock conditions.


Ambient Conditions

Prevailing conditions, (eg. temperature, humidity in surrounding air or other media).


Back to top

B


Basis Weight (see also Grammage)

A measurement of paper mass per unit area, normally expressed as grams per square metre.


Beating or Refining

The mechanical treatment of the fibres in water to increase surface area, flexibility and promote bonding when dried.

Blotting Paper
Very absorbent and bulky, woodfree, sometimes made from a pulp of cotton or wool fibres 120-300gsm.

Brightness
Degree of reflection of a sheet of pulp or paper measured under standardised conditions; used to indicate the degree of whiteness. Originally was a judgement of the amount of light reflected to the eye from the surface of the paper, irrespective of the hue or saturation of colour. Is now measured by optical comparators. Many factors affect brightness, including the degree of bleaching of pulp, addition of chemicals such as titanium and fluorescent dyes. Top grades of test and book papers with these chemicals have brightness in the range 85-90+. Coated publication papers are in the high 70's. Newsprint was traditionally around 60, but bleaching of mechanical pulps has allowed newsprint brightness to be increased to 70+.

Broke
Paper or board that is discarded at any stage during its manufacture and is usually repulped. There are 2 kinds - wet broke, which is accumulated at the wet end of the papermaking machine; dry broke which is accumulated at any stage on the dry end of the machine, trimmings from the reeling, slitting and cutting operations, as well as paper or board rejected during sorting.

Bulk
The number obtained by dividing the thickness, in micrometres of paper or board, by its grammage. i.e. mass per unit volume.


Back to top


C


Calender

A machine intended to smooth or otherwise finish the paper and consisting essentially of a certain number of superimposed rolls of which only one is power driven.

Caliper
Refers to the thickness of a paper sheet measured under specified conditions and is generally expressed in micrometres (microns).


Cellulose Fibre

The fibrous materials remaining after the non-fibrous components of wood have been removed by pulping and bleaching operations used in making paper.


Chemical Pulp

Pulp obtained by cooking wood with solutions of various chemicals, usually under pressure and temperature. The principal chemical processes are the sulphite, sulphate (kraft) and soda processes.


CIE Whiteness

An internationally-recognised standard of paper brightness developed in Europe by the Centre Internationale d'Eclairage (CIE).


Clay Coated Boards

Cartonboard with a surface application of clay-based coating that enables high quality printing.


Conditioning

Exposure of paper sample to a controlled environment so that the moisture content of the sample will reach equilibrium with a specified atmospheric condition - Laboratory: The exposure of paper in accurately controlled and specified atmospheric conditions so that its moisture content may reach a reproducible equilibrium. Press Room: Bringing the paper to the appropriate temperature so that paper humidity environment specified by the manufacturer will result in the best Press Room performance.


Container Materials

Components used in the manufacture of corrugated fibre containers and/or solid fibre combined boards. usually two liners separated by a corrugated fluting or fillerboard.

Converting Paper
Any paper which may be converted by a separate operation, to produce a paper of different characteristics or to produce a product quite distinct from the original paper. Thus, kraft paper is made and sold to be converte into asphalt paper, waxed paper, gummed tape or paper bags; writing paper is converted into envelopes and alike.


Cotton Linters
Cotton linters is a by-product of vegetable oil industry. The fibre length is approximately 3 to 5mm, much shorter than the cotton used for textiles which is around 25mm in length. Traditionally, paper making used cotton rags to produce very strong papers with a "quality feel" which was not present with papers produced with wood pulp. This had led to the concept of cotton as the premium fibre to be used for letterhead and stationery papers. Cotton is the purest form of cellulose and therefore retains its properties longer than wood pulps. For this reason, a cotton content is normally specified for archival papers.


Cracking

A defect in linerboards caused by the separation of the liner ply and/or the formation of fissures (cracks) in the surface of the liner during creasing.


Crinkles

A term applied to the crepe effect produced in fairly heavy papers, the term ‘crepe’ generally being applied to tissue and lightweight papers. Paper that is extensible in both directions may be described as 'crinkled and corrugated'.


Cross-Direction (CD)

The direction at right angles to the direction of running a paper machine.


Curl

Tendency of paper by itself to bend or partly wrap around the axis of one of its directions. Usually caused by changes in weather, faulty drying on the paper machine or in a multi-ply sheet with differing ply composition.


Back to top

D


Dandy Roll

A skeleton cylinder covered with a woven wire cloth. The dandy roll is one method of applying watermarks to paper while wet. Used for smoothing the surface and ‘closing’ the formation. It is positioned after the forming area of the wire and usually after the second flowbox.


Deckle

The untrimmed edge of paper as it comes off the machine. (Also used to denote the width of the web).

Density

Density generally is the ratio of the weight of paper to the volume (ie. high density paper has a high weight to volume ratio).


Dimensional Stability

Paper or board changes in its dimension and flatness with variation in its moisture content and it's termed dimensionally stable when such changes are of a low order.

Duplex

A term which, when applied to a paper or board, may refer to texture, finish, or colour:
(a) A duplex texture may be produced by a multi-ply machine, using two different stocks or by lining a board with two kinds of stock:it may also be obtained by pasting (laminating) together two papers or boards of different texture.
(b) Duplex finish is a finish which is rough on one side and smooth on the other (eg. a machine glazed finish). A paper may have a linen finish on one side and a burlap finish on the other, or any other combination may be used.
(c) Duplex colour may be produced by pasting together two papers or boards with different colour, by staining one side and not the other, or by coating the two sides with different colours.
(d) A general term applied to a paperstock or board having two or more plies.
(e) In the bag industry, the use of two separate sheets in the manufacture of a bag.
(f) When applied to a cutter, means two cutting stations on the machine.


Back to top

E


Embossed

A finish imparted to paper by means of raised or depressed engravings on steel rolls so as to leave a visible surface design on the paper. Normally a conversion process.


Back to top

F


Formation

The manner in which the fibres of a sheet of paper or board are distributed, disposed and intermixed to constitute the sheet.

Fourdrinier

The terms applied to the standard type of paper machine which was produced by Fourdrinier about 1800.

Furnish

The specific mixture of raw materials, both pulp and chemicals, from which a particular grade is manufactured.


Back to top

G


Ghosting

A printed image can also be seen on the reverse side of a sheet, caused by the vapourisation of the ink solvent.


Gloss

Refers to the specular reflection of light and occurs when specular reflection exceeds the diffuse reflection from various viewing angles. Paper gloss can be measured with various geometrics of illumination. For most printing papers, gloss is measured at an angle of 85 degrees to a plane normal to the surface.


Grain

In machine-made papers, the direction in which the majority of the fibres are aligned, (ie. the machine direction). Long grain is synonymous with “machine direction” and short grain with "cross direction".


Grammage (GSM)(see also Basis Weight).

Weight per unit of a paper i.e. basis weight in grams per square metre.


Back to top

H


Hard-sized

Refers to a type of paper which has been treated with considerable size to resist moisture penetration. Opposite of "slack sized".


Hickies

Specks of dust or dirt adhering to the printing plate or blanket cause spots of colour with a halo around them in print.


Humidity

The moisture condition of the air. Actual humidity is the number of grains of moisture in the air at any given time. Relative humidity is the percent of moisture relative to the maximum which air at any given temperature can retain without precipitation.


Back to top

I


Intaglio

A printing process where the image is etched below the surface of the plate, ink fills these grooves and then the sheet is printed. Gravure is a common example of this process.


Internal Bond Strength

A measure of the internal strength of paper and paperboard. Also, the bond between body stock and coating as measured by Dennison’s Graded Waxes. Low internal bond strength could lead to picking the clay from the paper when tacky inks are used.


Back to top

K


Kraft Paper

A strong pulp produced by the sulphate process by digestion of wood with sodium hydroxide and sodium sulphide.


Back to top

L



Laid

Papers with a ribbed appearance produced by a mould or dandy roll which has wires parallel to each other and not woven.

Letterpress

In this form of printing the image is raised, then inked and printed.


Lignin

An organic compound which is the main non-cellulosic constituent of wood. It bonds the cellulose fibres together. During pulping, chemicals dissolve the lignin, thus releasing the cellulose fibres as pulp.


Linerboard

Boards used as facing materials in the manufacture of paperboard containers as for the outer layers of plaster building boards.


Long Fibre Pulp (LF)

A general term given to pulps produced from soft woods such as pine. The fibre length of the pulps is long compared with that of hardwood.


Back to top

M


Machine Coating

Applying coating to paper on the paper machine on which the paper is made. Can be done by several processes, the most successful of which are the doctor coaters such as the 'trailing blade coater' or the 'air-knife' method.


Machine Direction (MD)

Direction of forward movement on the paper machine. Also called "with the grain". The direction at right angles to this is called the "cross direction" or "cross grain".


Machine Finish (MF)

The finish applied on the paper or board machine, commonly referred to as MF.


Machine Glazed (MG)

The finish produce din glaze on wire side of a sheet as it is passed in contact over a single, large diameter, steam heated cylinder. The finish is commonly referred to as MG.


Mechanical Pulp

Pulp produced by separating fibres from wood by abrasive (grinding) mechanical action only. This pulp is usually called "groundwood" pulp and the fibre strength within the pulp can be varied by using stones of different surfaces. Pulp can also be produced from chips processed through refiners.


Moire Pattern

A pattern of coloured dots can be seen, especially in a printed photo- graphic image. This is caused by incorrect screen angles of halftone dots, thus causing an obvious grid of dots in the image.


Moisture Content

The percentage of moisture found in paper or pulp.


Misregister

When printing more than one colour, the succeeding plate fails to register to the previous printed sheet.


Mottle (paper)

Non-uniform colour of a paper sheet, whether accidental or intentional.


Mottle (printing)

When a printed area, especially a solid area of colour, looks uneven or spotty due to varying degrees of the absorption of ink.


m2 Yield/Tonne

A measure of the surface area of paper or paperboard which is obtained from a tonne of product.


Back to top

N


Newsprint

A generic term used to describe paper of the type generally used in the publications of newspapers. Often referred to as mechanical pulp, this paper normally has a very high "groundwood" content.


Nominal Grammage

The aim grammage for a grade when conditioned at specified humidity and temperature.


Back to top

O


Offset Lithography

The method of printing where the image is transferred first from the plate to a rubber covered cylinder (blanket) from where it is printed.


Opacity

Property of a paper which prevents "show-through" of printing from one side of sheet to the other. The opposite of transparency.


Out-of-Square

Paper which is trimmed improperly so the corners are not true 90 degrees. This will result in difficulty when the presser does not have a good guide edge to work from for accurate register.


Back to top

P


pH

Measure of the hydrogen ion concentration and the degree of acidity or alkalinity on a scale ranging from 0 to 14. Neutral points is 7.0 with 7.0 to 0 being increasingly acid and 7.0 to 14 increasingly alkaline.


Picking

Fibres in the paper which tend to pull away from the surface during the printing process. This occurs when the tack or pull of the ink is greater than the surface strength of the paper.


Pin Holes

Small holes in paper due to fibres being drawn through the mesh of the wire by excessive suction. Small holes in paper caused by fine particles of sand or similar, when the paper is calendered, the particles are crushed and fall out leaving a hole.


Piping

A type of creasing or ribbing in paper due to irregular tension and drying.


Ply

The separate webs which make up the sheet formed on a multi-ply machine. Each formed ply adds one web which is pressed to the other, the plies adhering firmly upon drying.


Porosity

Property of containing connected air voids. The porosity of paper is evaluated by measuring the air permeability under standardised conditions.


Profile

An outline of the variation in a measured property. Usually a graph showing the variations in basis weight, moisture content or other property from point to point in a paper web, either in the machine direction or cross-direction.


Pulping

To remove lignin or mechanically grind in refiners in the first stage of transforming wood into paper.


Back to top

R


Ream

A term denoting a number of sheets of paper ranging from 480 to 516, most commonly 500.

Reel Hardness

A measure of web tension in a reel (related to grammage and thickness).


Reel Set

MD curl induced into paper or board when winding or reeling a web into a roll. Usually occurs near the core.


Back to top

S


Set Off

When a printed image is accidently transferred or smudged on to the back of the following printed sheet within a stack. This usually occurs if the ink has not had enough time to dry and if the sheets are stacked too high or too tightly.


Semi-chemical Pulp (NSSC)

Pulps originally used in making corrugating medium but recently used in bleached papers. Wood chips are partially cooked in sodium sulphite and then reduced to fibre by the mechanical action of an abrasive mill. Its advantage is that it makes a relatively strong pulp from hardwoods.


Shadow Mark (paper quality)

A defect in paper appearance which looks like the drilling pattern in a suction roll. It is due to opacity effects caused by areas of vacuum and pressure as the wet web passes over a suction roll.


Shadow Mark

Otherwise known as an embossed mark, the design is pressed directly into the wire covering of the dandy roll using a two-piece (male and female) die. The embossed mark is pressed into the surface of the dandy roll and produces a mark which is darker than the background. A shadow mark can also be debossed, which produces a mark that is lighter than the background, therefore a combination of embossing and debossing can be used to create a tone effect.


Sheet Fed

A printing press which is fed paper in single sheets rather than from a ream.


Short Fibres (SF)

A general term relating to pulp made from hardwoods, (eg. eucalypt) because of their short fibre length relative to the fibre length of softwoods(eg. short-fibred pulp).


Silk Screen

A form of printing were a frame or screen is stretched with silk material and ink is passed through the screen, under pressure, via a soft rubber blade onto the sheet below.


Size

A material added to the stock or to the surface of the sheet to impart water-resistance to the sheet.


Smoothness

The texture of the surface of the paper. Also called its "finish". Generally determined with a tester which measures the time required for a given volume of air to flow between the surfaces of the paper sample and a piece of optically-flat glass under standard loading conditions.


Stiffness

Rigidity, resistance to bending, inflexibility.


Strike-through

In printing, the ink soaks through the sheet of paper to the reverse side. This is related to the absorbency of the paper and consistency of the ink.


Surface Sized

Paper that has been treated with starch or other sizing material at the size press of the paper machine.


Back to top

T


Tensile Strength

The force parallel to the plane of the specimen required to produce failure in a specimen of given width and length under specified conditions of loading.


Top Side

Paper web side that has not been in contact with the wire during manufacture. Also termed "felt side".


Translucency

Ability to transmit light without being transparent.


Two Sidedness

Difference in properties between two sides of the same sheet, (ie. front and back) in colour, formation or finish.


Back to top

W


Watermark

Design formed among the fibres of a sheet as a result of the wet paper web coming into contact with the pattern of the dandy roll. The paper becomes thinner and more translucent where the fibres are displaced by the raised design.


Wire Mark

Traditionally, wire was sewn onto the dandy roll to form a pattern, logo or signature. Today, we utilise electrotype, the design of which is created by computer, engraved into bee’s wax and immersed into an electrolysis bath. The resultant electrotype is coated with solder and affixed to the dandy roll using a soldering iron. A wire mark sits proud of the dandy roll and produces a mark which is lighter than the background.


Wavy Edges

A warping effect in paper which is the result of the edges of the sheet having picked-up moisture and expanded. This will normally happen only in a pile which prevents the centre of the sheets from picking-up the same amount of moisture and levelling-out or “cockling”. It is usually a warm weather problem. It is caused by improper balance between the moisture content of the paper or too high humidity in the air.


Web Fed

A printing press which prints from a ream of paper rather than from single sheets.


Wire Side

The side of the sheet of paper which was originally in contact with the forming wire or fabric.


Woodfree

Paper made entirely from chemical pulps, (eg. kraft pulps) as distinct form papers incorporating mechanical pulp or groundwood. Usually applied to fine papers.


Back to top

 

UNITS

Bending Resistance CD - MN

Bending resistance measures the stiffness of the paper or board, more often applied to Board grades. CD refers to cross direction, and MD to machine direction, bend resistance is higher in the machine direction. The higher the value the stiffer the paper.

Bending Resistance MD - MN
Bending resistance measures the stiffness of the paper or board, more often applied to Board grades. CD refers to cross direction, and MD to machine direction, bend resistance is higher in the machine direction. The higher the value the stiffer the paper.


Burst - KPa

Burst measures the internal strength of the paper. Paper is held against a flexible membrane and pressure is applied to the membrane forcing it to expand against the paper. The pressure required to burst the paper is the Burst figure quoted. The higher the figure the stronger the paper.


Brightness
- %
Brightness is a measurement of the reflectance of a sheet of paper, particularly in the blue region of the spectrum. It is sometimes used as an indication of how white the sheet is but in general CIE whiteness is a better measurement.


CIE Whiteness - (D65/10°)

CIE Whiteness is a international standard for measurement of Whiteness and is used to compare the whiteness of papers. It attempts to match the way the humans perceive white by measuring the reflectance of the paper with a bias towards the blue region of the spectrum as a blueish white is generally perceived as being whiter than a neutral white. A perfect white surface reflects all the light which shines on it and has a whiteness of 100. Many paper grades have a whiteness well above 100 due to the addition of Fluorescent whitening agents. These absorb UV light and re-emit it as blue light.


Cobb 1min. (multisheet)
- Mls/sqm
This is a measure of how much water will absorb into the paper in grams per square metre per minute. If you have an 80gsm sheet of paper and it has a cobb of 30gsm, it means that 30gsm of water have absorbed into the paper over a minute. The cobb test has traditionally been a useful measure to approximate how quickly liquids such as ink and glues will absorb into the paper. Cobb values of 50gsm are considered high.

Colour a*
This is a measure of how Green or Red the sheet of paper is. A value of zero is neither green nor red. The more positive a number goes the more red the paper becomes. The more negative the number goes the more green the paper becomes.

Colour b*
This is a measure of how Blue or Yellow the sheet of paper is. A value of zero is neither blue nor yellow. The more positive a number goes the more yellow the paper becomes. The more negative the number goes the more blue paper becomes.

Colour L*
This is measure an alternative measure of lightness and varies from 100 for perfect white to 0 for absolute black. Copy paper grades can typically be around 93.

Density - G/cm³
Density is calculated by dividing the grammage of the paper by its thickness. A high density sheet (>0.9) will be relatively thin at a given grammage while a low density sheet will be more bulky.


Droop Rigidity CD - mm

Droop rigidity measures the stiffness of the paper or board, more often applied to lighter weight grades. CD refers to cross direction, and MD to machine direction, Droop rigidity is higher in the machine direction. The higher the value the stiffer the paper.

Droop Rigidity MD - mm
Droop rigidity measures the stiffness of the paper or board, more often applied to lighter weight grades. CD refers to cross direction, and MD to machine direction, Droop rigidity is higher in the machine direction. The higher the value the stiffer the paper.


Fluorescence

Fluorescence measures the amount of fluorescent whitening agent present in the paper. Optical brightening agent absorbs UV light and re-emits it as visible blue light. Under lighting with a UV component this makes the paper appear more blue and brighter. All high white grades have high levels of optical brightener. Less than 5 fluorescence indicates very little optical brightener is present.


Gloss

Gloss is a measurement of the mirror like reflection of light which gives the paper a glossy appearance. In high gloss papers light is reflected from the paper at the same angle as it approached. This is most apparent in smooth coated papers. Uncoated papers tend to have a rougher surface and reflect light in all directions.


Grammage - g/m²

Weight per unit area of paper (ie basis weight) in grams per square metre. Gsm is a primary property that describes paper. If a lower gsm product is used, paper properties such as stiffness and opacity are normally lower.


IGT - m/s

IGT is a measurement of the surface strength of the paper. A tacky ink is applied to sample of the paper at an increasing speed. As the speed increases the peeling force applied to the paper also increases and the speed at which the fibres begin to be pulled from the sheet is recorded as the IGT. A high IGT (>300) indicates a strong surface strength suitable for demanding offset applications.


Moisture - %

This is the percentage of moisture or water in paper when it is made. As a general rule higher moisture (7%) suits offset printing and lower moisture (5%) suits laser printing. Letterhead papers normally go through offset and laser processes so the moisture content is in between. Care should be taken when storing and handling paper not to allow it to pick up or lose moisture as this will usually cause curl.


Opacity - %

Opacity is a measure of how easy it is to see through a piece of paper. Fibre properties refining, the shade of the paper, the grammage, and the amount of filler used, all contribute to the final opacity developed in a sheet of paper. High opacity is important for most printing papers and office papers to ensure that print from the opposite side of the sheet is not visible and that print from a printed sheet below is not visible.

Parker Print Surf
Parker print surf is a surface smoothness measurement particularly good for very smooth papers. A lower value indicates a smoother surface.


Porosity (Bendtsen)
Porosity can be measured by a number of methods including Sheffield and Bendsten. These measure the rate at which air will pass through a sheet of paper at a set pressure. A high porosity indicates the paper allows the air to travel through relatively easily. In some applications a low porosity may be required, such as if the paper is processed using a vacuum, a low porosity paper forms a better seal against the vacuum.


Porosity (Sheffield) -
Sheffield Units
Porosity can be measured by a number of methods including Sheffield and Bendsten. These measure the rate at which air will pass through a sheet of paper at a set pressure. A high porosity indicates the paper allows the air to travel through relatively easily. In some applications a low porosity may be required, such as if the paper is processed using a vacuum, a low porosity paper forms a better seal against the vacuum.


Roughness (Bendtsen)

Bendsten and Sheffield Roughness are similar methods used to measure how smooth the surface is. Roughness is a key property that describes the surface texture of the paper. A low roughness paper (smooth) allows finer details to be printed. A high Roughness paper gives the paper a tactile quality. The test unit involves the measurement of airflow under a very uniform metal ring that is placed on the paper's surface. If the surface is rough, more air escapes and you obtain a higher airflow. The higher the number the rougher the sheet.


Roughness (Sheffield)

Bendsten and Sheffield Roughness are similar methods used to measure how smooth the surface is. Roughness is a key property that describes the surface texture of the paper. A low roughness paper (smooth) allows finer details to be printed. A high Roughness paper gives the paper a tactile quality. The test unit involves the measurement of airflow under a very uniform metal ring that is placed on the paper's surface. If the surface is rough, more air escapes and you obtain a higher airflow. The higher the number the rougher the sheet.


Stretch CD

Stretch is a measure of the degree to which a paper will stretch before breaking under a tensile force.


Stretch MD

Stretch is a measure of the degree to which a paper will stretch before breaking under a tensile force.


TEA CD

TEA is the Tensile Energy Absorption, ie the amount of work required to break the sheet under tension.
.
TEA MD
TEA is the Tensile Energy Absorption, ie the amount of work required to break the sheet under tension.


Tear Resistance CD

Tear measures the amount of energy required to tear a sheet of paper. Low tear papers have a brittle feel and will snap fairly easily once a tear is started. High tear papers are tougher.

Tear Resistance MD

Tear measures the amount of energy required to tear a sheet of paper. Low tear papers have a brittle feel and will snap fairly easily once a tear is started. High tear papers are tougher.


Tensile Strength CD

Tensile strength measures the amount of force required to break a strip of paper. Tensile is important where high stresses are applied to the paper during processing.


Tensile Strength MD

Tensile strength measures the amount of force required to break a strip of paper. Tensile is important where high stresses are applied to the paper during processing.

Thickness -
Microns (µ)
This is the thickness of a sheet of paper measured in micrometres (or microns for short). These are sometimes referred to as "ums". 0ne thousand microns is one millimeter. 80gsm copy paper is around 100 microns thick so a ream of 500 sheets will be about 50mm thick. At a given grammage a thicker sheet is normally rougher and stiffer.

Wax Pick
- Wax Pick Number

This is a measure of paper surface strength. A melted wax stick is inverted and pressed against a sheet of paper until the wax cools. The wax stick is pulled away from the sheet of paper. If the papers surface fibres are pulled out of the sheet then the paper has failed the test. Wax sticks are available at many adhesion levels from 2 to 26. The higher the wax pick number the better the paper's surface strength. Critical wax strength number (CWSN) is the way test data should be presented. This means that a particular paper showed no surface/fibre pick when tested with a wax stick of number of say 14. Higher numbers can of uncoated papers can indicate that product will be less prone to dusting. However, slit edge quality is an important property also for minimal dust buildup.


Wet Burst

Wet burst refers to the burst strength when the paper has been saturated. It is normally compared to the normal burst strength to indicate the proportion of the sheets strength that is lost when it is wet. Some grades have wet strength agents added to retain more of the sheets strength when wet.


Wet Burst Retention

Wet burst retention is the ratio of wet burst to normal burst it indicates the proportion of the sheets strength that is lost when it is wet. Some grades have wet strength agents added to retain more of the sheets strength when wet.


Wet Tensile Retention

Wet tensile retention is the ratio of the tensile strength of a wet sheet of paper to normal tensile strength. It indicates the proportion of the sheets strength that is lost when it is wet. Some grades have wet strength agents added to retain more of the sheets strength when wet.

Back to top