A perforation is a small hole in a thin material or web. There is usually more than one perforation in an organized fashion, where all of the holes are called a perforation. The process of creating perforations is called perforating, which involves puncturing the workpiece with a tool.

Perforations are usually used to allow easy separation of two sections of the material, such as allowing paper to be torn easily along the line. Packaging with perforations in paperboard or plastic film is easy for consumers to open. Other purposes include filtrating fluids, sound deadening, allowing light or fluids to pass through, and to create an aesthetic design.[1]

Various applications include plastic films to allow the packages to breathe, medical films, micro perforated plate and sound and vapor barriers.

Perforations US1940 issues-2c


Pins and needles

"Volcanic" perforations made with a needle punch
Orientatiepaalperforatorpinnetjes Silva 433
A needle punch used in orienteering

Rotary pinned perforation rollers are precision tools that can be used to perforate a wide variety of materials. The pins or needles can be used cold or heated. Cold perforation tools include needle punches.

There are a handful of manufacturers that specialize in hot and cold needle perforation tooling and equipment. In materials that have elasticity this can result in a "volcano" hole that is preferred in many applications.

Pinned rollers can be made from a variety of materials, including plastic, steel, and aluminum.

In more brittle films, cold perforation can cause slitting rather than creating a round hole, which can jeopardize the material's integrity under pressure. The solution to this is often heating the pin; i.e. hot pin perforation. Hot perforation melts a hole in the material, causing a reinforced ring around the hole. Hot needle perforation also assists when high density pin patterns are utilized, as the heat aids the perforation of the material.

Die and punch

Die and punch sets can be used for thicker materials or materials that require large holes; this process is the most common for metalworking. The workpiece is sheared by pressing (either by machine or hand tool) the punch through the workpiece and into the die. The middle section of the workpiece is scrap; commonly known as the chad in paper and similar materials. The punch and die are shaped to produce the desired shaped hole. The clearance (the distance between the outside circumference of the punch and the inner circumference of the die) must be properly maintained to ensure a clean cut. Burrs are produced on the side of the workpiece that is against the die.[1]

Common applications are fruit and vegetable bags, hole punching and ticket punching.

Laser perforation

Laser cutting can place many precise holes in a web. Laser perforations look similar in many respects to hot needle perforations. However, laser systems are expensive. The big advantage of laser perforation is the consistency of the hole size, compared to mechanical perforation. This is very important in modified atmosphere packaging for fresh produce. The laser perforation is often carried out on roll slitting machines (slitter rewinder) as the printed material is slit down to the finished roll size.


Stamp US 1954 2c Jefferson coil pair
Perforation holes on a pair of coil stamps
Paper perforator
Paper perforator

Perforation frequently refers to the practice of creating a long series of holes or slits so that paper or plastics can be torn more easily along a given line: this is used in easy-open packaging. Since the creation of perforation devices in the 1840s and 1850s, it has seen use in several areas.

Postage stamps are one common application of this, where small round holes are cut in lines to create individual pieces. Perforations on stamps are rather large, in the order of a millimeter, in comparison other perforated materials often have smaller holes.

It is common for cheque-books, notebooks and legal pads to have perforations making it easier to tear out individual pages or leafs. Perforation is used in ways to separate loose leaf (or even a form of graph paper from a ringed binder). A fine perforation next to the rings allows the page to be separated from the book with no confetti.

Screwcaps on glass or plastic bottles are sealed with a ring at the bottom of the cap attached by perforation. Twisting the cap has the effect of rupturing the material between the perforations and indicating that the original seal has been broken.

Perforated punch card

The edges of film stock are perforated to allow it to be moved precise distances at a time continuously. Similarly, punched cards for use in looms and later in computers input and output devices in some cases were perforated to ensure correct positioning of the card in the device, and to encode information.

Perforation of steel strips is used in the manufacture of some zesters and rasps.

Historically, perforation patterns other than linear were used to mark stamps. A series of patents had been issued in the late 19th Century for perforation machines to be used on rail lines for ticketing. Libraries and private collections used similar perforating stamps to mark ownership of books. End sheets, title pages, and image plates were punched with the namesake of the collection.[2] Today, similarly elaborate perforation patterns continue to be used in orienteering.

Bread bags for some bread often have micro-perforations in the plastic, which is supposed to keep the bread fresh by releasing excess moisture.[3] Similarly, bags of concrete use small perforations to allow air to escape while they are being filled.[4]

See also


  1. ^ a b Todd, Robert H.; Allen, Dell K.; Alting, Leo (1994), Manufacturing Processes Reference Guide, Industrial Press Inc., pp. 103–104, ISBN 0-8311-3049-0.
  2. ^ admin (2010-12-01). "LHRT Newsletter". Library History Round Table (LHRT). Retrieved 2017-06-08.
  3. ^ "Micro-Perforated Bags".
  4. ^ "Weight of cement bags reduced by BSW Machinery". World Cement.
16 mm film

16 mm film is a historically popular and economical gauge of film. 16 mm refers to the width of the film; other common film gauges include 8 and 35 mm. It is generally used for non-theatrical (e.g., industrial, educational) film-making, or for low-budget motion pictures. It also existed as a popular amateur or home movie-making format for several decades, alongside 8 mm film and later Super 8 film. Eastman Kodak released the first 16 mm "outfit" in 1923, consisting of a camera, projector, tripod, screen and splicer, for $335. RCA-Victor introduced a 16 mm sound movie projector in 1932, and developed an optical sound-on-film 16 mm camera, released in 1935.

Boerhaave syndrome

Esophageal rupture is a rupture of the esophageal wall. Iatrogenic causes account for approximately 56% of esophageal perforations, usually due to medical instrumentation such as an endoscopy or paraesophageal surgery. In contrast, the term Boerhaave syndrome is reserved for the 10% of esophageal perforations which occur due to vomiting.Spontaneous perforation of the esophagus most commonly results from a full-thickness tear in the esophageal wall due to a sudden increase in intraesophageal pressure combined with relatively negative intrathoracic pressure caused by straining or vomiting (effort rupture of the esophagus or Boerhaave's syndrome). Other causes of spontaneous perforation include caustic ingestion, pill esophagitis, Barrett's esophagus, infectious ulcers in patients with AIDS, and following dilation of esophageal strictures.In most cases of Boerhaave's syndrome, the tear occurs at the left postero-lateral aspect of the distal esophagus and extends for several centimeters. The condition is associated with high morbidity and mortality and is fatal without treatment. The occasionally nonspecific nature of the symptoms may contribute to a delay in diagnosis and a poor outcome. Spontaneous effort rupture of the cervical esophagus, leading to localized cervical perforation, may be more common than previously recognized and has a generally benign course. Preexisting esophageal disease is not a prerequisite for esophageal perforation but it contributes to increased mortality.This condition was first documented by the 18th-century physician Herman Boerhaave, after whom it is named. A related condition is Mallory-Weiss syndrome which is only a mucosal tear.

In case of iatrogenic perforation common site is cervical esophagus just above the upper sphincter whereas spontaneous rupture as seen in Boerhaave's syndrome perforation commonly occurs in the lower (1/3)rd of esophagus.

Continuous stationery

Continuous stationery (UK) or continuous form paper (US) is paper which is designed for use with dot-matrix and line printers with appropriate paper-feed mechanisms. Other names include fan-fold paper, sprocket-feed paper, burst paper, tractor-feed paper, and pin-feed paper. It can be single-ply (usually woodfree uncoated paper) or multi-ply (either with carbon paper between the paper layers, or multiple layers of carbonless copy paper), often described as multipart stationery or forms. Continuous stationery is often used when the final print medium is less critical in terms of the appearance at the edges, and when continuously connected individual sheets are not inconvenient for the application. Individual sheets can be separated at the perforation (leaving a slight serration), and sheets also have edges with punched holes, which also can be removed at the perforation (one typical format).


Not to be confused with the secondary tympanic membrane of the round windowIn the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear, and then to the oval window in the fluid-filled cochlea. Hence, it ultimately converts and amplifies vibration in air to vibration in fluid. The malleus bone bridges the gap between the eardrum and the other ossicles.Rupture or perforation of the eardrum can lead to conductive hearing loss. Collapse or retraction of the eardrum can cause conductive hearing loss or cholesteatoma.

Film perforations

Film perforations, also known as perfs and sprocket holes, are the holes placed in the film stock during manufacturing and used for transporting (by sprockets and claws) and steadying (by pin registration) the film. Films may have different types of perforations depending on film gauge, film format, and intended usage. Perforations are also used as a standard measuring reference within certain camera systems to refer to the size of the frame.

Some formats are referred to in terms of the ratio "perforations per frame/gauge size" to provide an easy way of denoting size. For instance, 35mm Academy is also known as 4 perf-35mm; VistaVision is 8 perf-35mm; the long-time standard Todd-AO 70 mm film is 5 perf-70mm; and IMAX is 15 perf-70mm. This description does not indicate whether the film transport is horizontal or vertical, but uncertainty is precluded because there are currently no horizontal systems using the same number of perforations on the same gauge as a vertical one.

Gastrointestinal perforation

Gastrointestinal perforation, also known as ruptured bowel, is a hole in the wall of part of the gastrointestinal tract. The gastrointestinal tract includes the esophagus, stomach, small intestine, and large intestine. Symptoms include severe abdominal pain and tenderness. When the hole is in the stomach or early part of the small intestine the onset of pain is typically sudden while with a hole in the large intestine onset may be more gradual. The pain is usually constant in nature. Sepsis, with an increased heart rate, increased breathing rate, fever, and confusion may occur.The cause can include trauma such as from a knife wound, eating a sharp object, or a medical procedure such as colonoscopy, bowel obstruction such as from a volvulus, colon cancer, or diverticulitis, stomach ulcers, ischemic bowel, and a number of infections including C. difficile. A hole allows intestinal contents to enter the abdominal cavity. The entry of bacteria results in a condition known as peritonitis or in the formation of an abscess. A hole in the stomach can also lead to a chemical peritonitis due to gastric acid. A CT scan is typically the preferred method of diagnosis; however, free air from a perforation can often be seen on plain X-ray.Perforation anywhere along the gastrointestinal tract typically requires emergency surgery in the form of an exploratory laparotomy. This is usually carried out along with intravenous fluids and antibiotics. A number of different antibiotics may be used such as piperacillin/tazobactam or the combination of ciprofloxacin and metronidazole. Occasionally the hole can be sewn closed while other times a bowel resection is required. Even with maximum treatment the risk of death can be as high as 50%. A hole from a stomach ulcer occurs in about 1 per 10,000 people per year, while one from diverticulitis occurs in about 0.4 per 10,000 people per year.

Halfpenny Yellow

The Halfpenny Yellow is Malta's first postage stamp. It was first issued on 1 December 1860 and was only valid for local postage. It continued to be used until Malta's first definitive set was issued on 1 January 1885, and during its 25 years of use, it was reprinted 29 times.

Leather crafting

Leather crafting or simply leathercraft is the practice of making leather into craft objects or works of art, using shaping techniques, coloring techniques or both.

Les UX

The UX (for Urban eXperiment) is an underground organization that improves hidden corners of Paris. Their works have included restoring the Pantheon clock, building a cinema, complete with bar and restaurant, underneath the Trocadéro, restoring medieval crypts, and staging plays and readings in monuments after dark. The group's membership is largely secret, but its spokespeople include Lazar Kunstmann.

Meconium peritonitis

Meconium peritonitis refers to rupture of the bowel prior to birth, resulting in fetal stool (meconium) escaping into the surrounding space (peritoneum) leading to inflammation (peritonitis). Despite the bowel rupture, many infants born after meconium peritonitis in utero have normal bowels and have no further issues.

Infants with cystic fibrosis are at increased risk for meconium peritonitis.


Mediastinitis is inflammation of the tissues in the mid-chest, or mediastinum. It can be either acute or chronic. It is thought to be due to four different etiologies:direct contamination

hematogenous or lymphatic spread

extension of infection from the neck or retroperitoneum

extension from the lung or pleuraAcute mediastinitis is usually caused by bacteria and is most often due to perforation of the esophagus. As the infection can progress rapidly, this is considered a serious condition.

Chronic sclerosing (or fibrosing) mediastinitis, while potentially serious, is caused by a long-standing inflammation of the mediastinum, leading to growth of acellular collagen and fibrous tissue within the chest and around the central vessels and airways. It has a different cause, treatment, and prognosis than acute infectious mediastinitis.

Space infections: Pretracheal space – lies anterior to trachea. Pretracheal space infection leads to mediastinitis. Here, the fascia fuses with the pericardium and the parietal pleura, which explains the occurrence of empyema and pericardial effusion in mediastinitis. However, infectious of other spaces can also lead to mediastinitis.

Nasal septum perforation

A nasal septum perforation is a medical condition in which the nasal septum, the cartilaginous membrane dividing the nostrils, develops a hole or fissure.

This may be brought on directly, as in the case of nasal piercings, or indirectly, as by long-term topical drug application, including intranasal ethylphenidate, methamphetamine, cocaine, crushed prescription pills, or decongestant nasal sprays, chronic epistaxis, excessive nose picking and as a complication of nasal surgery like septoplasty or rhinoplasty. Much less common causes for perforated nasal septums include rare granulomatous inflammatory conditions like granulomatosis with polyangiitis. It has been reported as a side effect of anti-angiogenesis drugs like bevacizumab.

Perforated eardrum

A perforated eardrum or punctured eardrum is a rupture or perforation (hole) of the eardrum which can occur as a result of otitis media (ear infection), trauma (e.g. by trying to clean the ear with sharp instruments), explosion, loud noise or surgery (accidental creation of a rupture). Flying with a severe cold can also cause perforation due to changes in air pressure and blocked eustachian tubes resulting from the cold. This is especially true on landing.


Peritonitis is inflammation of the peritoneum, the lining of the inner wall of the abdomen and cover of the abdominal organs. Symptoms may include severe pain, swelling of the abdomen, fever, or weight loss. One part or the entire abdomen may be tender. Complications may include shock and acute respiratory distress syndrome.Causes include perforation of the intestinal tract, pancreatitis, pelvic inflammatory disease, stomach ulcer, cirrhosis, or a ruptured appendix. Risk factors include ascites and peritoneal dialysis. Diagnosis is generally based on examination, blood tests, and medical imaging.Treatment often includes antibiotics, intravenous fluids, pain medication, and surgery. Other measures may include a nasogastric tube or blood transfusion. Without treatment death may occur within a few days. Approximately 7.5% of people have appendicitis at some point in time. About 20% of people with cirrhosis who are hospitalized have peritonitis.


Philately (; fi-LAT-ə-lee) is the study of stamps and postal history and other related items. It also refers to the collection, appreciation and research activities on stamps and other philatelic products. Philately involves more than just stamp collecting, which does not necessarily involve the study of stamps. It is possible to be a philatelist without owning any stamps. For instance, the stamps being studied may be very rare, or reside only in museums.

Postage stamp separation

For postage stamps, separation is the means by which individual stamps are made easily detachable from each other.

Methods of separation include:

perforation: cutting rows and columns of small holes

rouletting: small horizontal and vertical cuts

diecutting: cut paper to shape using a metal die—used for self-adhesive stamps.

Protein kinase inhibitor

A protein kinase inhibitor is a type of enzyme inhibitor that blocks the action of one or more protein kinases. Protein kinases are enzymes that add a phosphate (PO4) group to a protein, and can modulate its function.

The phosphate groups are usually added to serine, threonine, or tyrosine amino acids on the protein: most kinases act on both serine and threonine, the tyrosine kinases act on tyrosine, and a number (dual-specificity kinases) act on all three. There are also protein kinases that phosphorylate other amino acids, including histidine kinases that phosphorylate histidine residues.Phosphorylation regulates many biological processes, and protein kinase inhibitors can be used to treat diseases due to hyperactive protein kinases (including mutant or overexpressed kinases in cancer) or to modulate cell functions to overcome other disease drivers.

Uterine perforation

Uterine perforation is a potential complication of any intrauterine procedure. It may be associated with injury to surrounding blood vessels or viscera such as the bladder or intestine. If not diagnosed at the time of the procedure it can occasionally result in massive hemorrhage or sepsis; however, the majority of uterine perforations are sub-clinical and safely resolve by themselves without treatment and do not cause any significant long-term damage. Risk factors include cervical stenosis during trans-cervical procedures or decreased strength of the myometrial wall as in pregnancy or menopause.

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