Acoustical Flexible Polyurethane Foam Foam designed to be attenuated (dampen sounds), or be nonattenuted (transmit sound as in loud speakers).

Additive A material used to modify the properties, processing, or end use of a base polymer. The amount of additive used is usually expressed in parts per hundred (by weight) of the total resin in the polymer formulation.

Air Flow Amount of air expressed in cubic feet per minute, that can be drawn through a 2"x 2"x 1" foam sample at .5-inch water pressure differential. Air Flow is measured by a test (ASTM D3574).

Air Traps Voids in molded foam parts caused by encapsulation of air pockets during mold fill-out. These voids have smooth, shiny surfaces.

Amine A class of compounds used as catalysts in polyurethane foam reactions. Amines are characterized by having N, NH or NH2 groups in the molecule.

Antioxidants Materials which when added to a flexible polyurethane foam formulation improve the resistance of the foam to oxidative type reactions, such as scorch resulting from high exothermic temperatures.

Anti-Static Flexible Polyurethane Foam Foam that contains electrically conductive materials to prevent static electricity buildup or promote static discharge. It is used primarily in packaging applications, such as for electronic components.

ASTM American Society For Testing and Materials An organization devoted to the establishment of standard methods and procedures for testing materials in the United States.

Auxiliary Blowing Agent (ABA) An additive used in the production of foam which supplements the primary blowing agent (water), and can be used to make foam softer or lighter. Compounds used to produce gases to expand, or blow, flexible polyurethane foam during production. Auxiliary blowing agents are low temperature boiling solvents, such as methylene chloride, acetone, hydrochlorofluorocarbons, and isopentane.

Ball Rebound A test procedure (ASTM D3574) used to measure the surface resilience of flexible polyurethane foam. The test involves dropping a steel ball of known mass from a predetermined height onto a foam sample. The rebound height attained by the steel ball, expressed as a percentage of the original drop height, is the ball rebound resilience value.

Basal Cells Larger, irregular cells found just under the surface skin of a molded foam part.

Blowing The process by which flexible polyurethane is foamed during production. In all cases, blowing occurs when water and TDI react to form CO2. [Also see Auxiliary Blowing Agent (ABA).]

Board Foot A unit of foam measurement equal to a square foot of material one inch in thickness.

Board Stock Flat sheets of flexible foam cut from large blocks or buns of foam.

Boardy Flexible polyurethane foam with a stiff or rigid feel, generally indicated by high 25% IFD values and low compression modulus.

Bonded Foam Flexible polyurethane foam particles or shredded flexible polyurethane foam (often manufacturing scrap) that has been glued to form a useful product. The resultant foam block is "peeled" into the desired thickness. Largest use is for carpet cushion. [Also see Rebonded Foam.]

Bonding The combination of two or more components into a composite. Foam is often adhered to other foam grades or to polyester fiber.

Boston Chair Test Boston Fire Department test method to measure performance of flexible polyurethane foam padding materials when exposed to a fairly severe flaming ignition source. This test is a full scale composite test. Test method is now similar to California TB 133.

Bottom Out Lack of support under full weight load. This characteristic is often found in low-density foam. This term is very subjective, as a foam may bottom out with a heavy person, and be very comfortable to a lighter-weight individual. The problem can be reduced by specifying foam with higher density and/or greater compression modulus value.

Buffed Flexible polyurethane foam pieces that have been shaped or contoured by removal of foam using abrasives.

Bun A segment of foam cut off from continuously produced slabstock type of foam.

California 117 Foam Flexible polyurethane foam that will meet the component combustibility requirements of the California Bureau of Home Furnishings' Technical Bulletin No. 117 (TB117).

California Technical Bulletin 133 (TB 133) A composite test to determine the combustion performance of a complete furniture construction "system". This is designed to be an evaluation of furniture performance when exposed to a large ignition source. The composite test evaluates total furniture construction rather than foam, fabrics, fiber or other construction components on an individual basis.

Catalyst A chemical that changes the rate of reaction of a chemical process, but is not consumed or produced during the reaction. (Catalysts are required for foam production to balance rates of competing reactions and to attain desired physical properties.)

Cell The cavity remaining in the structure of flexible polyurethane foam surrounded by polymer membranes or the polymer skeleton after blowing is complete.

Cell Count The number of cells per linear inch or centimeter, expressed as pores per inch or pores per centimeter.

Cell Opening In foamed materials, the breaking of membranes within the cell structure, permitting flow of air through the material.

Cell Size The average diameter of the cells in the final flexible polyurethane foam product, often measured in micron units.

CFC-Free Foam Flexible polyurethane foams that have been made without the use of chlorofluorocarbons as auxiliary blowing agents.

Compression Force Deflection (CFD) A measure of the load bearing ability of a foam. It is the force exerted against a flat compression foot larger than the specimen to be tested. The value can be expressed at 25%, 40%, 50%, and/or 65% compression (ASTM D3574). Note: previously called "CLD (Compression Load Deflection)".

Clickability The ability of a flexible polyurethane foam to recover from the pinching effects of die-cutting.

Closed Cells Foam cells having intact cell membranes thereby reducing or eliminating passageways for airflow.

Closed Pour The case in molded foam production in which the mold lid is closed and locked and the foaming mixture is introduced through one or more special ports in the lid of the mold.

Coarse Cells Large cells averaging 20 to 30 cells per lineal inch or fewer.

Cold Molding Molding process for the production of high-resiliency foam in which the foam is cured at or near room (ambient) temperature. Pouring is carried out without adding heat.

Colorant Dyes or pigments added to impart color to the final foam.

Combustion Modified Foam Flexible polyurethane foams manufactured by using additives based on chlorine, bromine, and phosphorus chemistry to reduce ease of ignition. Hydrated alumina or melamine is also used.

Combustion Modifying Additive A material that, when added to flexible polyurethane foam, will cause the foam to be more difficult to ignite or burn less rapidly or lose less weight during a fire than without that material. [Also known as "Fire Retardants".]

Comfort The ability of the cushioning structure to deflect at the surface and to conform to body shape, preventing a concentration of pressure on the body without bottoming out.

Compression Modulus Ratio of a foam's ability to support force at different indentation (or compression) levels. It is determined by taking the ratio of the foam's IFD at 25% indentation and 65% indentation (65% IFD/25%). The compression modulus is typically a function of foam chemical formulation and the manufacturing process. In most cases, the higher the density the greater the compression modulus. Other terms that are used interchangeably are: support factor, and modulus. The PFA recommends that compression modulus or support factor be used when referring to foam support properties.

Compression Set A permanent partial loss of initial height of a flexible polyurethane foam sample after compression due to a bending or collapse of the cell framework within the foam sample. A high value of compression set will cause a flexible polyurethane foam cushion to quickly lose its original appearance with use, leaving its surface depressed or "hollowed out". Compression set is measured in the lab by compressing a foam sample 90% of its thickness (or down to 10% of its original thickness) and holding it at 70 degrees C (or 158 degrees F) for 22 hours. Compression set is most commonly expressed as a percentage of original compression. Other deflections, times, and temperatures can be used.

Conventional Flexible Polyurethane Foam Polyether type polyurethane foams made by the basic manufacturing process without polyol modifiers or other additives.

Convoluted A foam fabrication process involving the use of a special cutting equipment to produce a foam sheet with dimples. The base under the dimples can be varied in thickness. Peaks can be produced from 1/2" to over 4" in height. Foam dimples can be produced in a number of shapes including egg-like designs, waves, squares or sharply-defined points.

Core The internal portion of foam, free of any skin.

Core Density The density of the foam sampled without skin, glue lines or compressed sections at or near the center of the final foamed shape.

Crushing Usually a mechanical or vacuum-assisted procedure to open the closed cells of a high resilience slabstock or molded foam.

Cure A term referring to the process whereby chemical reactions approach completion. At 100% completion, a foam should have 100% of the physical properties attainable with that particular formulation.

Cure Time The length of time required for sufficient reaction completion to develop a desired level of polymer strength and dimensional stability and to attain ultimate physical properties.

Dead Foam Foam that has a low resiliency and only slowly regains its original shape after deformation.

Deflect To compress, usually by a specified amount or percentage.

Demold Time The time between the discharge of the foam ingredients from the mixing head and the time at which a molded object may be removed readily from the mold without tearing or altering its shape and without post-expansion.

Densified A material that has been made more dense by permanently compressing a unit mass into a smaller volume.

Density A measurement of the mass per unit volume. It is measured and expressed in pounds per cubic foot (pcf) or kilograms per cubic meter (kg/m3) (Test Method ASTM D3574).

Die Cutting The "stamping out" of foam into parts, useful for long runs of cut parts requiring consistency in size.

Discoloration The gradual yellowing of foam due to a photochemical reaction. It is faster in sunlight than in artificial light, although it occurs in both. Fresh foam may discolor in the center of the block as a result of thermal or chemical events. (Does not affect physical properties.)

Dish Description of what occurs when a weight is placed on the center of a cushion or mattress and the corners rise up in response.

Durability As applied to flexible foams, the term refers to how well a foam retains its load bearing capacity and shape with use. Most measures of durability are done with laboratory-scale tests.

Dynamic Fatigue A durability test performed in the laboratory using roller-shear or pounding type mechanisms. A roller, longer than the foam width, is rolled back and forth across the foam. The roller is mounted in an offset position to impart a shearing action. (ASTM D3574).

Elastomer Polymers which resist and recover from deformation produced by force, similar in behavior to natural rubber.

Elephant Skin Surface creasing effect due to lateral resistance of a stiff, thick flexible polyurethane foam when compressed parallel to its face.

Elongation The percent that a specially shaped sample will stretch from its original length before breaking. (Test Method ASTM D3574).

Exotherm The heat released as a by product of some chemical reactions. All flexible polyurethane foam production reactions are exothermic.

Fatigue (Flex Fatigue) A softening or loss of firmness. Fatigue can be measured in the laboratory by repeatedly compressing a foam sample and measuring the change in IFD.

Filled Foam The addition of inorganic materials such as marble dust, barium sulfate, silica or clay, in foam to increase the density. Fillers are often added to increase the Support Factor. Filled polyurethane foam may be inappropriate for some applications, if the polymer content of the filled foam is not sufficient for the intended application before fillers are added. The fillers are not chemically bonded into the foam polymer. They are instead mechanically trapped within the molecular structure of the polymer. Filled foams with low polymer content or a high percentage of filler material tend to have less strength and durability.

Fine Cells A term used to describe foam with a cell count of 80 or more per lineal inch.

Fingernail Test A subjective test to determine the recovery of flexible foam when it is indented with a fingernail or sharp object.

Fire Retardants A material that, when added to flexible polyurethane foam, will cause the foam to be more difficult to ignite or burn less rapidly or lose less weight during a fire than without that material. [Also known as "Combustion Modifying Additives".]

Flame Lamination The practice of bonding flexible foam to a fabric or other material (film, etc.) by melting one surface of the foam with a flame source and quickly pressing it to the other substrate before the melted material resolidifies. [Also called Flame Bonding.]

Flex Fatigue The loss of foam firmness after flexing the foam a predetermined number of cycles.

Foam A lightweight cellular material resulting from the introduction of gas bubbles into a reacting polymer.

Formulation The list of chemicals and their relative amounts to be used in the preparation of a foam.

Friable A term used to indicate the crumbling, flaking, or powdering of a foam when the surface is rubbed.

Frothing A foaming technique in which air or other gases that are mechanically whipped into the polyurethane mixture using a high-shear mixer prior to the foam reaction.

Gel Time The time between the discharge of the foam ingredients from the mixing head and the point at which the foam has developed enough gel strength to resist light impressions and is dimensionally stable.

Graft or Polymer Polyol Polymers with active hydroxyl groups that have other organic groups or polymers "grafted" to the polyol molecule. These grafted organic compounds serve to reinforce the strength or modify other properties of the flexible polyurethane foam product.

Hand Is the feel of the foam as the hand is rubbed lightly over the surface. For most furniture, bedding and textile applications, foam having a stiff or hard feel to the touch is described as having poor hand. In home furnishings, foam with a good hand has a springy, velvet feel, while abrasive pads, firm filler, and some packaging require a hand that is quite the opposite.

High Resilience (HR) Foam A variety of polyurethane foam produced using a blend of polymer or graft polyols. High resilience foam has a less uniform (more random) cell structure different from conventional products. The different cell structure helps add support, comfort, and resilience or bounce. High resilience foams have a high support factor and greater surface resilience than conventional foams and are defined in ASTM D3770.

Hot Molding A flexible molded foam production process in which high oven temperatures are used to drive the curing reaction in foams made from relatively low-reactivity polyols.

Hot Wire Cutting A high-temperature wire used to cut foam. This fabrication process is used typically for intricate parts. A ventilation hood should be used with this technique to exhaust fumes. Note: This procedure is not suitable for all foams.

Humid Aging An accelerated aging test method under conditions of high humidity and temperature. (ASTM D3547)

Hydrophilic An affinity for water.

Hydrophobic A repellency for water.

Hysteresis The ability of foam to maintain original support characteristics after flexing. Hysteresis is the percent of 25% IFD loss measured as a compression tester returns to the normal (25% IFD) position after measuring 65% compression. Lower hysteresis values, or less IFD loss are desirable. Current research indicates that hysteresis values may provide a good indication of overall flexible foam durability. Low hysteresis in conventional foam is equal to less IFD loss.

Indentation Force Deflection (IFD) A measure of the load bearing capacity of flexible polyurethane foam. IFD is generally measured as the force (in pounds) required to compress a 50 square inch circular indentor foot into a 4 inch thick sample, typically 15 inches square or larger, to a stated percentage of the sample's initial height. Common IFD values are generated at 25 and 65 percent of initial height. (Reference Test Method ASTM D3574 ). Note: Previously called "ILD (Indentation Load Deflection)".

Integral Skin Foam A molded foam having a dense, tough outer skin and a relatively lower density core. The product is achieved in a single pour using a combination of chemical and mechanical aids.

Isocyanate A shorthand name for the family of diisocyanates which are one of the two major ingredients in the chemical process by which polyurethane foam is made.

Laminating The bonding of layers of foam and/or other materials together into a single composite. This may be accomplished through adhesives or through heat processes like flame lamination.

Latex A natural rubber product which is not related to polyurethane foam.

Loop Slitter A mechanical slitter which allows continuous slitting of long buns of foam.

Mixing Head The device that mixes two or more component streams before dispensing the foam-producing mixture to the foam production surface or mold.

Mold Packing The practice of purposely adding more material to the mold than is actually required to just fill it. The extra material serves to accommodate slight changes in material temperatures, mold temperatures, and pour patterns. It is also a way to improve load-bearing properties without changing the foam formulation.

Molded Foam A cellular foam product having the shape of the mold cavity in which it was produced.

Open Cell Structure A permeable structure in flexible foam in which there is no barrier between cells, and gases or liquids can pass through the foam. Most cell walls have been ruptured to varying extent.

Peeling The process whereby thin sheets of foam are cut from a cylinder of foam. Similar to plywood peeling.

Pieced Flexible polyurethane foam that has been glued together from two or more smaller pieces. Commonly seen in cushioning to create special shapes or properties, or to use up small pieces produced during fabrication.

Pockets The undesirable formation of large cavities or pockets in the foam structure. Pocketing is usually caused by rapid formation and/or release of the blowing agent before the polymer structure has gained sufficient strength to contain the gas. [Also see "Splits".]

Polyester A polymeric polyol containing ester groups in the main molecular chain or in side chains.

Polyether A polymeric polyol containing ether linkages (carbon-oxygen-carbon links) in the main molecular chain or in side chains.

Polymer An organic substance composed of repeating chemical units built up into large molecules.

Polymer Density The density of the material made up strictly by the foam chemistry without fillers or reinforcements included.

Polyol A key chemical in foam formulation which, when mixed with diiso-cyanates and other specific ingredients, produces the reaction that causes flexible polyurethane foam to form.

Polyurethane Generally, a polymer connected by urethane groups. Urethane linkage and its supplements result from the reaction of polyol with isocyanate.

Pore Size The number of cells per linear inch.

Preflex The practice of compressing a flexible polyurethane foam sample up to six times to a predetermined thickness before determining IFD. (Reference ASTM D3574). Also used for other properties (e.g. resilience for HR foams).

Prepolymer A reacted, but not completely polymerized product. In the polyurethane industry, this is usually a prereacted product formed by reacting polyol(s) or water with diisocyanate(s). The materials normally contain residual free isocyanate groups for further reaction with more polyol(s) or water to produce the final polymer.

Pressure Release Collapse Shallow surface voids and/or shear collapse on molded foam parts caused by the sudden release of internal mold pressure or failure of the mold to seal. Usually seen with shiny surfaces and a thin surface skin similar to cold collapse.

Primary Backing (carpet) The material through which the carpet fibers are tufted.

Prime Carpet Cushion Polyurethane carpet cushion which is made from slabstock polyurethane foam.

Protocol For Residential Walk-On Test A standardized testing procedure that can be used by carpet manufacturers, cushion producers, distributors and retailers to evaluate installed residential carpet system performance.

Rebonded Foam That foam resulting from a process of adhering small particles of foam back together again to make a usable cushioning product. Various adhesives and bonding processes are used. A typical application for rebonded foam is as carpet underlay. [Also see Bonded Foam.]

Recovery The return to original dimension and properties of a flexible polyurethane foam sample after a deforming force is removed. Reinforced Foam [See "Filled Foam".]

Resilience An indicator of the surface elasticity or "springiness" of foam. It is measured by dropping a steel ball onto the foam cushion and measuring how high the ball rebounds.

Reticulated Foam Flexible polyurethane foams characterized by a three-dimensional skeletal structure with few or no membranes between strands. Reticulated foams are generally used as filters, acoustical panels, and for controlled liquid delivery.

Roll Goods Flexible polyurethane foam that has been peeled from a foam "log" or slit from a bun and rolled onto a core for handling purposes. Rolled foam sheets are commonly used for large area padding, such as carpet padding and as quilting foam in mattresses.

Scorch A yellow or brown discoloration of the foam, particularly in the core. Scorching is caused by excessive heat during the exothermic reaction. It occurs mainly in high-water flexible slabstock formulations.

Seam The splice line formed by two or more separate pieces of flexible polyurethane foam that have been bonded together.

Shiners Light reflected from intact cell walls, noticeable on the cut surfaces of flexible polyurethane foam. A large number of shiners, or shiny spots, indicates a foam with many closed cells.

Shredded Foam Flexible polyurethane foam that has been mechanically torn into small pieces or crumbs, for the purpose of creating a loose filling material.

Skin The higher-density outer surface of a foam usually occurring when the foam surface cools more rapidly than the core.

Slab A section of foam cut from the interior of a large bun.

Slab Stock Flexible polyurethane foam made by the continuous pouring of mixed liquids onto a conveyor, creating a continuous loaf of foam.

Slabstock Production Process One of the two basic procedures used to manufacture foam. A continuous process in which the reacting foam chemical mix is dispensed on to a moving conveyor belt where the foaming process is completed. This foam is subsequently fabricated into useful shapes.

Slitting The process where sheets of foam are cut from a rectangular foam block.

Static Fatigue The loss in load bearing properties of a flexible polyurethane foam sample under constant compression of 75% for 17 hours at room temperature. (See "Test Method ASTM D3574"). Struts The structural members of a foam material. These roughly triangular features contain most of the solid polymer and form the cell shape.

"Supersoft" Foam Foams that have an IFD measurement within the 4 to 10 pound range having a comparable feel to fiber.

Support Factor (see Compression Modulus) Support Factor = 65%IFDÖ25%IFD determined after one minute of rest or recovery. When the support factor is known it can be used in conjunction with a known 25% IFD value to determine the 65% IFD value. Seating foams with low support factor are more likely to bottom out under load.

Surface Firmness The number of pounds of force necessary to indent a foam sample by 25% of its original height.

Surfactants A term to describe substances that provide resiliency and stability to thin films and that markedly lower the surface tension of liquids, thus permitting easier bubble formation. An integral part of the foam manufacturing chemistry.

TDI An abbreviation for toluene diioscyanate.

Tear Strength A measure of the force required to continue a tear in a foam after a split or break has been started and expressed in pounds per inch (lbs/in.). This property is important in determining suitability of foam in applications where the material is sewed, stapled, or otherwise anchored to a solid substrate. Also important in demoldability. (ASTM D3574).

Tensile Strength The pounds per square inch of force required to stretch a material to the breaking point. (Reference ASTM D3574).

Tight Foam Flexible polyurethane foam with many closed cells, resulting in low air flow measurements.

Total Vertical Motion (TVM) The deflection of a seating system during sitting.

Urethane Actually a misnomer as applied to polyurethane foam. A colorless, crystalline substance used primarily in medicines, pesticides, and fungicides. Urethane is not used in the production of urethane polymers or foams. The urethanes of the plastics industry are so named because the repeating units of their structures resemble the chemical urethane.

Virgin Foam Unfilled flexible slabstock foam that has not been processed in any manner other than cutting to shape.

Voids The undesirable formation of large cavities or pockets in a foam structure. Voids are usually caused by poor moldability or incorrect mold filling. In the case of foam buns, voids occur when then blowing and polymerization reactions are out of balance.

Water Blown Foam Flexible polyurethane foam in which the gas for expansion is carbon dioxide generated by the reaction between water and an isocyanate material. All flexible polyurethane foam is water blown, although auxiliary blowing agents are often used to obtain special physical properties.

Windows The thin membranes formed between cell struts.Windows may be present (a closed-cell foam) or absent (an open-cell foam) depending on the particular foam chemistry used.