GRAPHICS AND PREPRESS TERMS
- Places halftone dots in a consistent pattern, varying the size of the individual dots to simulate the tone values of the original.
- Highlight compensation applied to avoid imaging dots in the plate that are too small to allow full dot formation during plate processing.
- The adjustment of manufactured process images to be more color correct. This process is started with a layered PSD file that gives the production artist the ability to work easily within the file and determine how to properly align color for output and to match specific press targets.
A PSD file is a layered image file used in Adobe PhotoShop. PSD, which stands for Photoshop Document, is the default format that Photoshop uses for saving data. PSD is a proprietary file that allows the user to work with the images' individual layers even after the file has been saved.
- Also referred to as “Repeat”. The film measurement in the machine direction from the leading edge of one eye mark to the leading edge of the next eye mark. This represents the size of the impression or height of the bag or wrapper being converted.
- This is a screening technology unique to KODAK plates that applies a user definable texture pattern to the surface of the plate. The texture minimizes stray artifacts in solids, reduces patterning, increases solid density and reduces dot gain (specifically in shadows).
- Stochastic dot screens that provide more contrast and detail in images while fading shadows in a more natural way.
- Center face is Center web and the seal laps over side to side to create the seal.
- For every color to be printed, a plate is made and eventually put on a cylinder which is placed in the printing press. To make a complete picture, regardless of printing on flexible film or paper, the image transferred from each plate has to register exactly with the images transferred from the other colors. To ensure an accurate picture is made, mounting marks are made on the flexographic plates. These mounting marks can be microdots (down to 0.3 mm) and/or crosses. Special machinery is made for mounting these plates on the printing cylinders to maintain registration.
OFFSET FIN SEAL
- The face is centered on the web, and a fin is created on the back seal.
- A preview proof for reviewing the layout from dieline specifications applied to the art, to the color legend explaining the breakdown. The art is set up with all basic layout functions addressed. The preview should verify measurements, UPC, and correct copy. This is the typical proof that an authorized person will give approval to proceed to production.
- Overwraps utilizes a method of platemaking developed by Kodak. The method of plate development uses light-sensitive polymer. A computer-guided laser is used to etch the image onto the film negative. This method is commonly referred to as digital platemaking.
The polymer plate is then transferred to an exposure unit where ultra-violet light passes through the film. This hardens the areas of the polymer that will print the image. The remaining polymer has the consistency of chewed gum. The plate to be washed out is fixed in the washout unit on a base plate. The plate is washed out with a special mixture designed to remove the “gummy” unwanted plate material. Soft brushes scrub the plate to facilitate the "washout" process. The unit is equipped with a dual membrane filter. With this filter the environmental burdening is kept to an absolute minimum.
The freshly washed plate is then transferred to a drying oven to fully harden and cure the polymer. Once this step is complete the plate is ready to go to press.
PRESS CURVE, CHARCTERIZATION or FINGERPRINT (PROFILE)
- The process of running target images on a particular press to create a file that shows how the press renders and reproduces color. It is used to calibrate the color separation process to achieve the most accurate color match on press.
- KODAK software that separates files, RIP and process art files to TIFFs that make up each color used in a job. The TIFFs are then output to plates.
- Preparing files to RIP and process through the pre-press workflow and make plates that will successfully meet target color and print expectations on press.
- A contract proof usually serves as an agreement between customer and printer and as a color and copy reference guide for adjusting the press before the final press run. Most contract proofs are a prepress proof.
The primary goal of 'proofing' is to serve as a tool for customer verification that the entire job is accurate. Prepress proofing (also known as off-press proofing) is a cost-effective way of providing a visual copy without the expense of creating a press proof. If errors are found during the printing process on press, correcting them can prove very costly to one or both parties involved.
Press time is the most expensive part of print media. The main objective of proofing is to produce either a soft or hard copy of what the final product will look like on press. Hard-copy proofing usually involves ink-jet printing or other technologies (i.e. Laminate Proof) to produce high-quality one-off copies of the production artwork. Soft proofing usually involves highly color accurate wide-gamut computer displays.
"The printed proof is a simulation of the ultimate output - a CMYK press sheet. The mission of a proofing system is to create accurate predictions, not pretty pictures." In the best conditions the proofing process will actually try to emulate the effects of the printing press through color management and screening techniques.
- Graphics that are made up of pixels and have a specific resolution that will produce the desired sharpness and clarity of the image.
(RIP) RASTER IMAGE PROCESSOR
- A program that uses digital information to create dot patterns delivered to produce an image.
STANDARD FIN SEAL
- Face is shifted off center from the Web Center and a fin is created on the back seal.
- The film measurement in the cross direction from edge to edge. There are two references for this term. The first is the measurement from edge to edge of a finished slit roll that is ready to be shipped to the customer. The term “web width” is also used for internal manufacturing purposes which describes the “master web width” which is the width a much larger roll that will be later be slit down into individual finished rolls.
- An ink metering roll used in flexographic presses. The anilox roll provides a controlled amount of ink to be applied to the printing plate.
- In flexographic printing there are different pressures applied during printing sleeve rotation due primarily to the printing design. At high speeds, variances in the printed and non-printed areas of the plate when pressed against the central impression drum result in erratic movement or bounce of the cylinder. Bounce can be reduced by incorporating breaker bars into the outside areas of the web. Consideration should be given during the design process to reduce the effects of bounce during production printing.
- Cyan Blue, Magenta, Yellow, Black – inks used for reproducing process color images.
- Cyan Blue, Magenta, Yellow, Black, Orange, Green, Violet – inks used for reproducing process color images with a wider color spectrum. (See Expanded Gamut)
- A color calculation to determine if the printed colors pass or fail the specified color target. An industry standard variation of 2.0 Delta E represents when the human eye will begin to detect color shift. (See X Rite)
- Also known as reflection density. The light absorbing property of a substrate or film of ink as measured by a reflectance factor. The higher the density the darker or fuller the color.
- Is an increase in dot size inherent in the transfer of ink to a substrate. It is normally measured as a percentage increase. Flexography, in particular, has significant gain from the design dot size. Gain can cause process colors to be inconsistent and can fill in to cause the finished design to look dirty.
DOTS (RE PRINTED IMAGES)
- Are fine microscopic ink dots that make up the printed process (pictorial) image. The dots are normally round in shape.
EXTENDED GAMUT/EXPANDED GAMUT
- Extended Gamut (EG) is used to minimize spot colors, create more vibrant images, reduce printing costs as there are no changes of anilox rollers, no washing of ink pans, and not a lot of changeover except for plates. This is accomplished by adding two or three inks in addition to CMYK (Cyan, Magenta, Yellow, Black), to extend the color gamut and enable the press to print a wider range of colors. This standard extended gamut ink set is then used to simulate all of the many spot colors contained in the color library. With a wider range of color images look more vibrant.
- A term used to represent one print unit – e.g. bag, wrapper, label or pouch.
IMPRESSION, SETTING IMPRESSION
- Refers to the area of the printing plate that transfers the image to the print substrate. Setting Impression is the pressure required to transfer ink from the plate to the film.
- Printing composed of solid blocks of color with no variation in tone or saturation. A block of a specified color (for example, one chosen from a PMS color book) rather than a process color. It is also known as a spot color.
- Printing plates made of monomers and UV initiators that, when exposed to UV light, experience a chemical reaction to make the monomers join together to become a solid mass of polymers. Overwraps uses a digital plate format by Kodak which eliminates all oxygen during UV exposure to produce full flat top dots with sturdy bases and strong shoulders across the entire tonal range. The result is a printing form that is consistent, repeatable, resistant to changes in impression and wear from substrate or cleaning.
- A cylinder that is used to hold the printing plates during the printing process. The sleeve circumference is made to an exact size to match the “cut off” of the individual impression or a multiple of that “cut off”.
- Is the thickness of the photopolymer printing plates. Plates can vary in thickness based on the type of printing and the preference of the printer. Overwraps has standardized on plates that are 0.0067 inches thick. The thickness variation tolerance across the plate surface is minimal. Typical variation is no more than + - 0.00015 inches. Overwraps has strict requirements for the thickness of the relief area (floor of the plate) after it is processed in the imager during plate making. This prevents printing issues, as well as premature plate wear. (See Printing Plates)
- Refers to the number of impressions that a printing plate can print before it is replaced. Typically the process plates wear more rapidly than the line plates.
- Refers to the location of each color plate printing in relation to the other colors.
- Used to print the customer’s design. The image areas are raised above the non- image areas on the polymer plate. The ink is transferred from the ink roll which is partially immersed in the ink pan. Then it transfers to the anilox roll (or meter roll) which is an engraved roll which holds a specific amount of ink as it is covered with thousands of small cells that enable it to meter ink to the printing plate in a uniform thickness evenly and quickly. Ink is then metered to the printing plate via a scraper, called a doctor blade. The doctor blade removes excess ink from the anilox roller before inking the printing plate.
- Printing of pictorial images with CMYK (Cyan, Magenta, Yellow, Black) or a combination of CMYKOGVB. (Cyan, Magenta, Yellow, Black, Orange, Green, Violet, Brown)
- Less expensive film purchased and used for the exclusive purpose of press make ready which includes setting impression, register, and correct color matching on the press prior to running production.
- This is the two sided tape used to adhere the printing plates to the printing sleeve. There are several different types of sticky back that are designed to work with different printing plates and achieve optimal printing results.
- The Spectrodensitometer used for measuring color, opacity, ink density, and dot gain of printed materials. The X-Rite computer software located in the ink room office, and QA lab has a Pantone color library, as well as a customer specific library of colors saved when an item initially prints. Each time the same item is printed, Overwraps uses that reference standard to match color. Tolerances of up to 2 delta E are monitored during each printed order to assure color consistency within each order and from order to order. (See Delta E)
ADHESIVE LAMINATIONS—SOLVENT , SOLVENTLESS, WATER BASED
- Solvent based adhesive laminations are made with adhesive that uses a solvent to dilute and carry the adhesive and disperse it on the web. Solventless adhesives (used exclusively at Overwraps) is an adhesive type that uses a 100% solids chemistry combining a mixture of polyol and isocyanate to bond two films together with little or no VOC’s at a lower application weight cost than solvent based adhesives. A water based adhesive is typically a water and polyurethane or acrylic mixture used to bond two films together and is generally a lower performance adhesive for light weight snack food packaging.
AREA MEASUREMENT: MSI, YIELD, (SQUARE INCHES/LB. OR KG – MSI
- Thousand square inches calculated by multiplying the web width in inches by 12 by the length of the material in feet divided by 1,000. Yield - The measure of a film's coverage per unit weight. Values are expressed as (in2/lb.) in US standard and (m2/kg) in metric (or SI) units. Most packaging raw materials are sold by weight. However, because of density differences, the same weight of similar materials can produce different amounts of finished product. It is calculated by using this formula: 27.68/Density (g/cm3) x Thickness (inches) = Yield (in2/lb.). Metric calculation is 1,000/Density (g/cm3) x Thickness (micron).
- A film that is laminated to the printed web. Typically used as a sealant web in the lamination.
BAGS: SIDE WELD, BOTTOM SEAL, WICKETED, NON WICKETED, SIDE GUSSETED
- Side weld bags are folded and sealed on the sides with one opening. Bottom Seal bags are typically made from a tube of polyethylene film and sealed at the bottom. Wicketed bags have holes punched in the top, opened end of the bag and are placed on a wire wicket for ease of use. Non Wicketed bags are not hole punched and placed in cartons for shipment. A side gusseted bag is folded in the side of the pouch, allowing it to expand when contents are inserted.
BOTTOM GUSSETED, STAR SEALED
- A Bottom gusseted bag is folded in the bottom of the pouch, allowing it to expand when contents are inserted, and stand upright on the store shelf. Star Sealed bags are typically found in the trash bag industry and are manufactured by folding the bottom of the trash can liner over several times and then sealing it.
- Laminating two film layers together.
- A lamination by extrusion coating a plastic melt onto a base material while simultaneously pressing the coated stock against a second material, and then cooling rapidly to establish the bond between two layers.
- A fin seal brings the inside surfaces together and creates the seal, usually by heat sealing. The fin seal is generally not as aesthetically pleasing and uses more material than the lap seal. However the laminate can be simpler since the inside heat seal material is sealed to itself.
- An acronym for Hazards Analysis and Critical Control Points. It is the backbone of SQF system. HACCP is a management system in which food safety is addressed through the analysis and control of biological, chemical, and physical hazards from raw material production, purchasing and handling, to manufacturing, distribution and consumption of the finished product.
INK COVERAGE - %, LBS/MSI, LB/REAM
- The amount of ink printed on the film. Typically expressed as a percentage of ink on the web. LBS/MSI – a measurement of total coating weight on an order. LB/REAM – A measurement of the amount of ink in a ream of film.
- The internal order contract that Overwraps uses to define customer orders. The job jacket outlines everything from the item requested, quantities, have ready dates, materials, processing instructions, finished specification requirements and special instructions specific to the job.
- A lap seal overlaps the material for the distance required by the seal and creates the seal, usually by heat sealing. During sealing, the inside of the laminate must be able to seal to the outside, requiring that both sides of the laminate be heat sealable. The lap seal is generally more aesthetically pleasing and uses less material than the fin seal.
MASTER WEB WIDTH
- Roll width which is the measurement of the raw material to be printed or laminated from edge to edge.
- A film that the press prints and is the top layer of most packaging laminates. It may or may not be laminated to another layer of film. Surface printed films are typically not laminated to another layer of film. Reverse printed films are almost always laminated to another layer of film to lock in the inks, and protect the food from contamination.
- 432,000 square inches. The basic unit of measure on which product specifications are built. The 432,000 square inch ream is basic in figuring percentage of multiple components of a structure. To determine the percentage of a component, one needs the yield (square inches per pound) of the components, then divide the 432,000 by the yield of each component to get the pounds per ream for each component. Total all the pounds per ream of all components for a total weight per ream. Divide the total pounds for one ream of your structure by the pounds of each component to get the percentage for each component.
RECYCLABLE –NON RECYCLABLE
- Recyclable Plastic scrap that is capable of being removed or sorted from the solid-waste stream in an established program and returned to use in the form of raw materials or products. Most of the plastic waste we generate is recyclable. Examples of non-recyclable film are co-mingled plastics such as Clear OPP/Metallized OPP or foil laminates.
RTO, OXIDIZER, INCINERATOR
- Regenerative Thermal Oxidizer (RTO) is an industrial process for the treatment of exhaust air. The system is a type of thermal oxidizer that uses a bed of ceramic material to absorb heat from the exhaust gas. It then uses this captured heat to preheat the incoming process gas stream and destroy air pollutants emitted from process exhaust streams at temperatures upwards to 1,500 F. Each press exhausts the solvent laden air into the RTO and the exhaust is cleansed per compliance with clean air standards.
- An acronym for Standard Production Pounds of film required to produce an order.
- Inks that use solvent to carry the ink pigment and disperse it onto the printing substrate. Solvents are widely used to dissolve solid resins in order to produce a fluid base. Solvent is used to dilute, render more fluid, or control the viscosity of the ink. Major solvents used by Overwraps include Isopropyl Alcohol, Ethyl Alcohol, Normal Propyl Acetate, Normal Propyl Alcohol, Glycol PNP, and Ethyl Acetate. Siegwerk is our current ink supplier for surface printed inks (CT III, and Colorgloss systems), and reverse printed laminating inks (Access Lam system).
- An acronym for Safe Quality Foods and is recognized by retailers and foodservice providers around the world who require a rigorous, credible food safety management system. SQF is a system that is recognized by the Global Food Safety Initiative (GFSI) and links primary production certification to food manufacturing, food packaging, distribution and agent/broker management certification. It’s administered by the Food Marketing Institute (FMI). There are three levels of SQF certification. Overwraps attained the highest lever (3) in October of 2011. Level 3 certification incorporates quality management criteria. We are audited annually in the fall.
SUP, QUAD SEAL PTC ZIPPER, VELCRO STYLE
- SUP or stand up pouch. It has a bottom gusset to enable it to stand on the store shelf. Quad seal pouches have four sided seals and are typically found in coffee and pet food bags. A PTC Zipper is the most common zipper material used in pouches and refers to a zipper that requires pressure to close. Velcro Style zippers are a hook and loop fastener used to seal pouches.
- Stand Up Pouch – A package of flexible film that stands up on the shelf and mimics the point of sell characteristics of rigid packaging. The package is supported by forming a gusset or fold in the bottom of the bag. This gusset adds stability allowing the package to stand up on the shelf. Gusset size, height and width of bag are dimensions needed to create a template of the pouch. Additional specifications include the need for a reclosable zipper, “easy open” laser score, hang hole and tear notch.
- Laminating three layers together.
- A measurement of the amount of film that was not converted to good saleable film. Usually calculated by dividing the amount of lbs. or impressions, or footage shipped vs. what was used on an order.
WATER BASED INKS
- Ink that uses water and a very small percentage of Normal Propyl Alcohol to carry and disperse the ink on to the printing substrate. Overwraps purchases water based ink from Sun Chemical (Aquasurf ink system) to print non-woven face mask material.
- Generally used to describe a thin plastic material used in the manufacture of flexible packaging. Overwraps uses many different types of plastic film, but mostly Polyethylene (PE), Polyester (PET), Metallized Polyester (MET PET), Polypropylene (OPP), Metallized Polypropylene (MOPP), and Nylon (BON).
- An unsupported thin metal membrane, typically aluminum in thicknesses of 0.000285 or 0.00035 inch thick for cookie packaging, or 0.0014 inch thick for coffee packaging. It is the best barrier film available for excellent shelf life providing moisture and vapor protection of the packaged product. It is most often used as a middle layer web of a three layer film lamination with PET as the printed layer, and PE as the sealant layer. It can also be used as an outside layer of a two layer lamination.
- The material used at Overwraps to print hospital face masks, and gowns. It consists of a cellulose and polyester blend of fibers bound together with an acrylic polymer emulsion. The most common material we use is the Ahlstrom supplied 11399B for face masks.
- Biaxially Oriented Nylon film, also known as BOPA film, is made of polyamide resin, which can be used for a wide range of applications especially where high barrier requirements to gas, fat and transmission of aroma are necessary. It has high resistance to impact puncture and pin holing.
PE, CAST AND BLOWN
- Short for Polyethylene which is a plastic composed of polymers of ethylene. We purchase primarily clear or white PE, but also yellow, blue and red for explosives emulsion packaging. There are four general classifications: Low Density, Linear Low Density, Medium Density, and High Density. Overwraps primarily uses Blown Polyethylene film which is manufactured in an extruded plastic tube that is continuously inflated by internal air pressure, cooled, collapsed flat rolls, and subsequently wound into rolls. The tube is usually extruded vertically upward, and air is blown through a passage in the center of the die as the molten tube emerges from the die. An air ring provides air flow around the outside of the bubble to increase initial cooling close to the die. Air is contained within the blown bubble by a pair of pinch rolls, which also serve to collapse and flatten the film. Film thickness is controlled by the die-lip opening, by varying bubble air pressure, and by the extrusion and take-off rate. Thin films with considerable biaxial orientation can be produced by this method. Cast film is made by extruding a thin curtain of thermoplastic melt onto a highly polished chilled drum. After the film solidifies, it is edge trimmed and wound into rolls for further processing.
PET, METPET, SARAN, HEAT SEALABLE
- Polyester film is a high-performance film made from polyethylene terephthalate (PET) resin. It has high tensile strength, excellent dimensional stability, low moisture absorption, good retention of physical properties over a fairly wide temperature range (-70C° to 150°C), and good optical clarity. We typically use 48 gauge thickness PET. METPET is a metallized version of the PET on which a thin amount of aluminum has been vacuum-deposited, and is used primarily as a middle layer in a three layer film lamination with PET on the outside or printed side, and PE on the sealant side. It enhances the barrier properties and extends the shelf life of various packaged foods. SARAN is a coating made of poly (vinylidene chloride) (PVDC) and its copolymers. PVDC has very low permeability to gases and vapors, which makes it an excellent barrier material for packaging.
Saran is used most frequently as an applied coating to increase the barrier qualities of other base films.
HEATSEALABLE PET refers to PET that has a thin layer of heat sealable coating applied which enables it to seal to itself during the packaging form, fill and seal operation of foods.
PP, COEX COATED, BOPP, CPP, METPP
- Short for Polypropylene which is a plastic polymerized from propylene gas. Films are mostly oriented (OPP) or biaxially oriented (BOPP) which are stretched in both the machine direction as well as transverse direction. In this form they are used for high-clarity wrapping stock, and when printed, are the predominant film for snack food packaging. OPP film has excellent clarity, low elongation, good moisture-barrier properties, and good low-temperature performance. Gas barrier and heat-seal ability are provided by other added COEX material layers. CPP stands for Cast Polypropylene which is produced by extruding a thin curtain of thermoplastic melt onto a highly polished chilled drum. METPP is Metallized polypropylene and used primarily as a sealant web in a printed OPP lamination for snack food. It enhances the barrier properties and extends the shelf life of salted snacks.
SHINK BUNDLING FILM
- It is a super-strong polyethylene film used for packaging cases of water, soda, or other items needing to be bundled or bulk packed. It is stronger than standard shrink film and provides excellent puncture resistance. It can be used with packaging equipment and heat tunnels.
- A film used to shrink and conform to the contents of the package. Typically made of polyethylene, polypropylene, or poly(vinyl chloride), that is wrapped loosely about another container or product and then made to shrink and conform tightly about the container or product by the brief application of heat. Shrink films can be produced having biaxial or uniaxial shrinkage. Biaxial shrink film is most commonly used as package or product over-wrap while uniaxial shrink film is most commonly used for shrinkable label applications and for tamper evident neck-bands.
- A film made of low density or linear low density polyethylene used to bind the finished product to the shipping pallet.
- The material (FILM) on which some action, such as printing, coating, adhesive bonding, and so on is being performed.
- A Tyvek is a nonwoven product consisting of spun bond olefin fiber developed and manufactured by DuPont. It is used mainly as house wrap to provide moisture barrier, envelopes, and wristbands.
- A cross laminated polyethylene film. It is made with two oriented polyethylene films laminated with their orientation directions crossed at roughly 90 degrees (45 degrees from the machine direction). It is used primarily in the explosives and construction industries.
- A material designed to prevent, to a specified degree, the penetration of water, oils, water vapor, aromatic components or other gases. Barrier materials that we use extensively are Saran coated PET, Saran coated OPP, Acrylic coated OPP, and EVOH PE.
- A plastic film produced with minute voids that result in an opaque material. Cavitated materials such as polypropylene are used most often as ice cream bar wrap.
COF-STATIC , KINETIC
- Coefficient of Friction measuresthe slipperiness of a surface determined by observing the force required to pull a known weight over a surface. STATIC COF is the force required to initiate motion while KINETIC COF is the force required to continue the movement of the one surface over the other. Static COF is always greater than Kinetic COF. As a general rule, low coefficient of friction allows for lower power requirements and easier machining where flexible materials are being pulled over stationary machine parts. However too low a COF can also result in telescoping rolls, poor tracking, and packages that will slide when stacked.
- An extensible film is one that can be stretched easily. Most stretch wrap, and heat shrink films made of low density polyethylene, linear low density polyethylene and polyvinyl chloride are common examples.
- Specular reflection of light from the film surface.
- An instrument which is used to measure specular reflection gloss of a surface. Gloss is determined by projecting a beam of light at a fixed intensity and angle onto a surface and measuring the amount of reflected light at an equal but opposite angle. There are a number of different geometries available for gloss measurement, each being dependent on the type of surface to be measured. For materials as coatings and plastics the amount of reflected light increases with a greater angle of illumination, as some of the light penetrates the surface material and is absorbed into it or diffusely scattered from it depending on its color.
- A “cloudy” discoloration of a transparent film or coating.
- An instrument which is used to measure the transparency; haze, see-through quality, and total transmittance of a material, based on how much visible light is diffused or scattered when passing through a material. Transparency is important because a material needs to be more or less see-through depending on its practical usage, e.g. a grocery bag needs the light to be more diffused so that less can be seen while food packaging film needs the light to be less diffused so that the contents can be seen clearly. For reasons such as these haze meters are necessary to determine which material is needed for which practical purposes. The data gained from the haze meter can be transferred to a PC for further data processing to ensure a consistent product.
- A measure of the rate of water or moisture vapor transmission through a material. Expressed as WVTR (water vapor transmission rate), or MVTR (moisture vapor transmission). It is normally measured at 100% relative humidity, expressed in grams/100 square inches/24 hours, (or grams/square meter/24 Hrs.)
NON EXTENSIBLE FILM
- A film that is not easily stretched during the converting process. Common films such as polyester, nylon and polypropylene are not typically stretched when winding.
- Material that will not transmit light. Materials that Overwraps use include metallized PET, metallized OPP, and white opaque PE.
- Normally referred as Oxygen transmission rate (OTR) is the measurement of the amount of oxygen gas that passes through a substance over a given period. Standard conditions of testing are 0, 60 or 100% relative humidity. Units are cc/100 square inches/24 hours (or cc/square meter/24 Hrs.). (cc = cubic centimeters)