|A GLOSSARY OF EMBOSSING TERMINOLOGY|
The intent of this page is to educate the reader about the application of
embossing in manufacturing, and also to convince the
reader that Embossing Technologies is a valuable source for technical
information in this field.
Technical terms are defined according to their use in the absorbent tissue
A larger and broader glossary of paper terms can be found at
absorbency (or absorbancy) - Rate or Capacity - A measure of how a material or product picks up and holds a liquid, usually water. The two most important components of absorbency are rate and capacity. The rate of absorption is a measure of how fast a specific amount of liquid penetrates the material. The absorptive capacity is a measure the quantity of liquid that the material can hold. It is reported either on an area basis (grams of liquid per square meter of product), on a weight basis (grams of liquid per gram of product). The test result is very dependent upon how excess liquid is drained after the product is saturated. The effect of embossing upon absorbency is more obvious when very gentle drainage techniques are used.
How the embossing looks in the product.
For some products, the embossing is the visual "signature" of the product.
If the pattern clarity is too weak, irregular, or if the image is not recognizable,
then the consumer may see the embossing as not intentional, like water
damage, and a sign of poor quality.
Sometimes an embossing pattern fails to convey the intended image, and
looks more like something else entirely.
"It looked like a pillow on the drawing, but more like a pig on the tissue."
Other appearance problems associated with embossing are wrinkles, crushed
embossing elements, pattern strike-through (of a nested laminated towel),
ridging (or corrugation), and scuffing.
bath tissue - Also called bathroom tissue, toilet paper, or just TP. Its primary use is to clean and dry the skin after eliminating bodily wastes. It is supplied in roll form in most of the world, perforated for easy dispensing. Embossing is used to increase bulk, absorbency, softness, and product roll size.
A measure of the height of a stack of paper.
The terms thickness and caliper usually refer to a single layer of paper.
The number of layers in the stack varies from company to company, as well as
what constitutes a single layer.
For base paper, one layer usually consists of
a single ply of paper.
For the finished product, in its final form, one layer is often a unit of product,
which may be several plies combined together.
Some companies use the term "bulk" to mean thickness
divided by basis weight, which is essentially a measure
of specific volume.
The test result is very dependent upon how much compressive force is applied to
the product by the test instrument.
The effect of embossing upon bulk is more obvious when a relatively light
compressive force is used.
coin-edge embossing - A special embossing pattern normally seen around the edges of a dinner napkin or cocktail napkin. Its purpose is partly decorative and partly for ply bonding. Also see paper napkin.
commercial market - Manufacture and sale of product for use away from the home. Products are purchased by the case from a catalog, rather than from a display shelf. Storage space is often at a premium. Embossing patterns must be designed to accommodate this.
consumer market - Manufacture and sale of product for use in the home. Most of the volume is sold in grocery stores. Products and packaging must be designed for display on the store shelf, in very direct competition with other brands. Embossing plays a key part in this.
converting - A process which reduces a large sized parent roll provided by a paper machine into usable small sized rolls or folded products. The word "converting" may also mean the machinery that applies a converting process, or even the manufacturing area or department where it is done. A great deal of information about converting may be found at www.WebconInc.com.
cross direction (CD) -
Perpendicular to the direction of the flow of paper through a machine and in
the plane of the paper.
Almost all of the rollers in the machine have axes that are aligned in the CD.
Also see machine direction (MD) and
Z direction (ZD).
double-nip embossing -
Embossing a multi-ply product with two nips in parallel,
with one or more plies in each nip,
and then bringing all of the plies back together.
This recombination is often done with
A configuration where all of the plies pass through a single embossing nip is
called single-nip embossing.
element of a pattern - A small feature of an embossing pattern, usually completely surrounded by a region that is at a different elevation. Also called an "embossment". If the element is raised with respect to its surroundings, then it is called male. If the element is recessed with respect to its surroundings, then it is called female. With some embossing patterns, an element may contain smaller elements within it (see spot embossing).
embossing - To change the shape of a thin material or sheet from flat to shaped, so that there are areas that are raised and/or recessed from the rest of the surface, usually without rupturing the material (perf-embossing is the most notable exception). To learn more, see definition of embossing on the Technology page.
The main process used to create an embossing roller (cylinder) or an embossing plate.
Engraving changes the surface from smooth to shaped, either by etching (where material
is selectively removed) and/or by mechanical force (like knurling).
Etching methods include: chemical (acid or solvent), machining, and laser.
Steel embossing rollers are usually engraved with a combination of mechanical pressure
and acid etching.
Laser engraving is a relatively new process for making embossing rollers and is used to etch
a special coating that is applied to a steel roller.
For more in-depth information about engraving, and especially about laser engraving,
please see the article
"Using Laser Engraving in Tissue Embossing" by Carl Ingalls and Ed Giesler, which was
presented at CMM International 2003 Conference in Chicago on 15 April 2003.
facial tissue - A tissue paper product primarily used on the face. Sometimes inappropriately called Kleenex(R), which is a brand name owned and developed by Kimberly Clark many decades ago. Softness, especially the surface smoothness component, is highly valued in facial tissue, and especially in the "ultra premium" category. Many facial tissues have special materials added to improve the consumer's experience of the softness, through a process called lotionizing.
female - When applied to an embossing pattern that is engraved into the surface of an embossing roller or plate, "female" means that the pattern is composed of elements that are recessed into a flat background, like potholes in pavement. A male pattern is composed of elements that are raised up from a flat background, like mesas in a desert. However, many patterns are too complex to be described overall either as male or as female. These terms, male and female, work better when applied to a single embossing element.
finishing - A group of processes which add value by changing the intrinsic properties of the paper after the paper is formed and dried, after all of the papermaking processes have ended. Examples include embossing, calendering, printing, lotionizing, laminating, etc. Most finishing processes are done on converting machines. For more in-depth information about finishing processes, please see the article "Adding Quality Through Finishing Processes" by Carl Ingalls, which was presented at Tissue World Americas 2002 in Miami on 1 October 2002.
interdigitating embossing -
A type of embossing engagement where the raised elements of one engraved roller pass between
- but do not surround - similar raised elements of the opposing roller in an embossing nip.
Only male elements are able to engage in this way.
This is similar to the way that the fingers interlace when clasping hands together,
which is the origin of the term "interdigitating".
The most well known and practical application of interdigitating embossing is
laminating - A process which combines two or more plies of material with a strong bond, usually durable even when wet. For a much weaker bond, one of the ply bonding processes is used. Most premium consumer paper towels sold in the US are made with a process that combines laminating with embossing in a single unit. This is often called double-nip embossing laminating, and has several variations: nested, pin-to-pin, or random registration. Each variation requires two separate embossing operations (double-nip) that run in parallel, an adhesive applicator that places small amounts of glue on the tips of the raised elements of the paper while it is still in contact with one of the embossing rollers, a laminating area between the two embossing rollers (that may be either a closed nip or an open nip) where the plies are brought back together again, and a marrying nip (or shoe) where pressure is applied to make the adhesive bond stronger.
A process which improves the perception of the softness of a paper
product by the application of an invisible substance onto its surface.
The substance is often an oil, a wax, or a silicone.
This is most often applied to facial tissue.
male - When applied to an embossing pattern that is engraved into the surface of an embossing roller or plate, "male" means that the pattern is composed of elements that are raised up from a flat background, like mesas in a desert. A female pattern is composed of elements that are recessed into a flat background, like potholes in pavement. However, many patterns are too complex to be described overall either as male or as female. These terms, male and female, work better when applied to a single embossing element.
malleable - Literally, cabable of being worked by hammering, so that the material's shape can be extended by the application of mechanical force without breakage. This shape change should be permanent. Some materials must be heated to have this property. A more modern term is plasticity.
marrying nip or shoe - The part of the laminating process where the layers to be bonded are pressed together to make the adhesive form a better bond. The best way to do this is to apply pressure only at the glue-bond points, and avoid crushing any other part of the product. In nested lamination, this is done by using a marrying roll that is pressed against the same embossing roller that carried the paper which received the glue from the adhesive applicator. In pin-to-pin lamination, this is done in the laminating nip, which is where the two embossing rollers come into contact with each other. With random registration, it is not possible to avoid crushing unbonded areas of the product.
matched embossing or engraving - An embossing or engraving nip where the surfaces of the two rollers are perfectly matched, so that wherever the surface of one roller is raised by some distance, the corresponding surface on the other roller is recessed by the same distance. When the rollers are fully engaged, there is complete contact at every point along the nip line. In matched embossing, both rollers are engraved (as in steel-to-steel embossing), and one roller is usually made from the other in a matched steel engraving process using acid etching. In actual embossing practice, absolutely perfect matching is often avoided, in order to improve runnability, by creating a small gap between the rollers in selected areas of the pattern.
micro embossing -
Embossing with a very fine pattern, sometimes with the purpose of
simulating the wiremark appearance of a TAD product,
especially for bath tissue or paper towel.
Pattern fineness is often characterized by the density,
or number of elements per unit area.
Micro embossing is sometimes used as a background for
spot embossing and/or quilting.
nested embossing / laminating - One of several ways in which two layers or plies of embossed product are brought together in a laminating nip for a general process known as double-nip embossing laminating. Nested lamination means that the raised elements of each layer fit between each other, as in interdigitating, so that the tops of each element come into contact with the recessed area (or floor) of the opposing layer. Although it is theoretically possible to cause the embossing rollers to engage with each other (as in a nip) with nested embossing, most laminators run with a significant gap between the engraved embossing rollers to prevent any possible interference between the raised elements, just in case the rollers were not installed correctly. In normal practice, an adhesive glue is applied to the tips of the raised elements of only one of the two layers, and those tips are bonded to the floor of the other layer. Other versions of embossing laminating are pin-to-pin, and random registration.
nesting inside a roll of product or a stack of product - Nesting is when the embossing elements of one layer in the product fit into the embossing elements of the layer below it, similar to the way that bowls are stacked on a shelf, which causes them to take up less space. This is normally a disadvantage in a consumer product. In a roll product, this usually occurs in alternating bands of nesting and anti-nesting, which is described and illustrated in the article "Using Laser Engraving in Tissue Embossing" by Carl Ingalls and Ed Giesler.
The area where two rollers (cylinders) come into contact.
overall embossing -
Embossing "all over" the product with a fairly uniform density of embossing
elements, so that there are no significant areas
that have no embossing.
Usually, all of the elements are identical size and shape.
This style of embossing has fallen out of favor in the USA in recent years.
Most bath tissue in the US is now embossed with a
quilting pattern and/or
Also see micro embossing.
paper napkin - A tissue paper product used with food. Usually provided as a stack of folded sheets. Family or luncheon napkins are normally embossed with an overall embossing pattern, single ply, and quarter-folded. Dinner napkins are normally embossed with a coin-edge plus a decorative border, two or more plies, and many different types of folding patterns.
paper towel - An absorbent tissue paper product whose primary use is to absorb liquid, and is most often used to dry hands. It must have very good absorbency capacity, and must remain strong even when wet (a property known as wet strength). It is supplied in roll form in most of the world, perforated for easy dispensing.
parent roll - A large roll of paper, also called a jumbo roll, that is unwound into a machine that processes the paper in some way. In the absorbent tissue paper industry, these processes are usually called converting and finishing processes. The paper may be wound into the parent roll as single ply, or as multiple plies. In some special cases, the plies may be bonded together by some means (see ply bonding) before being wound into the parent roll.
perf-embossing - Embossing by a method that creates very small and discrete ruptures at precisely controlled locations within the material. This process was invented at Scott Paper Company decades ago and was originally used for ScotTowels(R) (trademark now owned by Kimberly Clark). Both embossing rollers in perf-embossing are usually engraved with the same pattern of discrete, raised, male elements, and the pattern is designed so that these elements pass between each other when the rollers are engaged in a nip. This is also known as interdigitating embossing.
performance of embossing - The ability of an embossing pattern or machine to deliver the required product properties. It is best determined and documented by a general method called a technology curve.
pin-to-pin embossing / laminating - One of several ways in which two layers or plies of embossed product are brought together in a laminating nip for a general process known as double-nip embossing laminating. Also known as "foot-to-foot" or "tip-to-tip". Pin-to-pin lamination means that the raised elements of each layer contact each other at their tips, which is where the bonding occurs. In normal practice, an adhesive glue is applied to the tips of the raised elements of only one of the two layers. The layers are pressed together in the lamination nip, where the two embossing rollers come into contact. Other versions of embossing laminating are nested, and random registration.
ply bonding - A process which causes plies to adhere together, usually rather weakly, so that it is fairly easy to separate the plies without tearing the paper. When the plies are bonded much more tightly, the adhesion process is usually called laminating. The most common ply bonding process uses a set of narrow knurled wheels that are pressed against a smooth anvil roll, and the multiple plies of paper are passed between the wheels and the anvil. The very high pressure at the contact points between the knurling and the anvil causes the paper to fuse into glassine. This method of ply bonding causes very visible lines in the product, sometimes described as "railroad tracks". Other methods include the application of a tiny amount of hot-melt glue between the plies, which is completely invisible.
properties of absorbent tissue paper products -
Also called attributes.
The term physical properties usually means the characteristics of the product that
can be measured by a machine (objectively) and reported as a number.
These include the paper properties of basis weight, bulk or thickness, absorbency,
strength (usually tensile strength), plus the as-packaged properties of roll diameter,
roll firmness, stack height, stack firmness, and product weight.
The term consumer perceived properties usually means the characteristics that
are better determined by human senses (subjectively).
These include appearance and softness, and sometimes fragrance.
quilting or quilted embossing -
Embossing which gives the general impression of a quilt, usually by
incorporating pattern features which suggest a network or lattice
of continuous or connected stitching lines, and with
open areas between the stitch lines that appear to puff up as a quilt
Quilting is often combined with spot embossing.
Also see overall embossing and
random registration embossing / laminating - One of several ways in which two layers or plies of embossed product are brought together in a laminating nip for a general process known as double-nip embossing laminating. In random registration, also called DERL (for double embossed random lamination), the embossing elements do not engage, and do not even maintain a fixed relationship to each other betweent the two embossing rollers. An adhesive glue is applied to the tips of the raised elements of one of the two layers to be laminated while it is still in contact with its embossing roller. Since registration is random, many of these elements will not come into good contact with the opposing layer, and the glue will be wasted. Additional pressure in the marrying nip or shoe will be required for a good bond. Other versions of embossing laminating are nested, and pin-to-pin.
ream - A quantity of paper, measured by area. For fine papers (not intended to be absorbent), one ream is usually 500 sheets. For absorbent tissue papers, one ream can equal 2880 square feet or 3000 square feet, depending upon the company.
ridging - The appearance of a series of circumferential ridges and valleys around a roll of product, where the roll appears to be corrugated like a tin can. The height and spacing of the ridges is very uniform. This is often considered a sign of poor product quality, and is usually caused by the design of the embossing pattern. One solution to this problem is described in the article "Using Laser Engraving in Tissue Embossing" by Carl Ingalls and Ed Giesler.
rotary embossing - Embossing by passing the material between two rotating cylinders that press the embossing pattern into the material.
rubber-to-steel (R/S) - Literally, embossing between two rollers where one has a steel surface that is engraved with an embossing pattern, and the other roller has a smooth rubber surface. In more recent years, this term has also been used when the engraved surface is a rigid material other than steel and/or the smooth surface is an elastic material other than rubber.
The ability of an embossing process (or any other process) to run smoothly,
without interruption, and with a minimum of attention from the machine
operator or from the maintenance department.
softness - Also known as handfeel. The consumer's experience of the feel of the tissue material is extremely important for premium-quality bath tissue and facial tissue products. However, there is no objective device that has been accepted as an accurate model or predictor of this subjective experience. The best methods of measuring softness or handfeel still rely on subjective evaluations by trained testing personel. However, there has been a lot of progress in understanding how softness is related to the more objective (and machine-testable) properties of tissue paper. Paul Hoffman) has been a major contributor to this work, and one of his articles on the subject may be found at Tissue Softness. Softness has several identifiable components. These include compressive or pillowy softness, flexibility or drape softness, and surface smoothness. Embossing often improves the first two, but rarely the last.
spot embossing - Also known as deco embossing. The "spot" is a small discrete region of embossing that is completely surrounded by a much larger area that is not embossed at all. The embossing rollers are designed to engage only at the spots, with plenty of space between them at the un-embossed areas. In a rubber-to-steel nip, the spots themselves will appear as male on the engraved roll. However, the embossing elements within those spots may be any combination of male and female. Also see overall embossing, quilting, and micro embossing.
steel-to-steel (S/S) -
Literally, embossing between two rollers where both rollers have steel
surfaces, and both are engraved with embossing patterns that are designed
to engage each other in some way.
One way of engaging is matched embossing.
Another engagement is interdigitating embossing.
The term "steel-to-steel" may also be used when one or both of the engraved surfaces
is a rigid material other than steel.
TAD - Acronym for Through Air Dried, which is a special tissue papermaking technology that produces desirable lower density for the same strength, resulting in better bulk, absorptive capacity,and softness for the same amount of fiber (basis weight). The TAD fabric that carries the paper through this part of the paper machine leaves a characteristic impression in the tissue paper that looks like very fine and very faint embossing (see micro embossing). , which comes from the TAD fabric that carries the paper through this part of the paper machine. This technology is being used on bath tissue and paper towels, but only rarely (if ever) on paper napkins or facial tissue. More conventional tissue papermaking technologies include: Light Dry Crepe (LDC) and Heavy Wet Crepe (HWC).
technology curve - A method for determining the entire range of performance of a process. The concept was originally developed by scientists and engineers at Scott Paper Company for use on papermaking processes and technologies. It has been adapted for use on finishing processes, and especially for embossing. For more in-depth information, please see the article "Adding Quality Through Finishing Processes" by Carl Ingalls, which was presented at Tissue World Americas 2002 in Miami on 1 October 2002.
tensile strength - The strength of a material when tested by pulling. In the absorbent tissue paper industry, this is usually reported as the maximum load that a one-inch wide specimen can bear before rupture, averaged over a number of specimens. The test can be done while the paper is dry or re-wetted (see wet strength). In most products, the test result is very dependent upon which direction the paper is pulled. The Machine Direction Tensile strength (MDT) is usually much greater than the Cross Direction Tensile strength (CDT). There are two other measurements that are often provided by the machine that performs the tensile test: Stretch and Energy. Of these, Machine Direction Stretch (MDS) is usually considered to be the most useful, and it is reported as the percentage of elongation of the test specimen at the moment that peak load occurred.
thickness or caliper - Thickness and caliper usually refer to a single layer (one sheet of product or one ply of paper), whereas bulk usually refers to a stack of layers. The problem with determining the thickness or caliper of a single layer is that the surface of an absorbent tissue paper is not only highly irregular, but also porous. There are always a few fiber ends protruding high above the rest, and holes that pass all the way through the paper. Neither of these have much effect upon how we normally think of thickness in a practical sense, and should be ignored. The preferred method of measuring the thickness of paper is to place it between two parallel flat plates that are pressed together with a predefined force. The gap between the plates is reported as the thickness of the paper. The test result is very dependent upon the pressure that is applied by the plates. The effect of embossing upon thickness is more obvious when a relatively light compressive force is used.
tissue paper - Paper that is very light in weight. There are two basic categories of tissue paper: wrapping tissue and absorbent tissue. Wrapping tissue paper is stronger, thinner, denser, and less porous than absorbent tissue paper, and is very rarely embossed. Absorbent tissue paper is often embossed to improve its absorbency even further.
Z direction - Perpendicular to the plane of the paper. If the paper is placed flat on a horizontal surface, then the Z direction would be vertical. Also see machine direction (MD) and cross direction (CD).