Glossary of Technical Terms







A Newton is the international unit of measure for force. One Newton is equal to 1 kilogram meter per second squared. 1 N of force is the force required to accelerate an object with a mass of 1 kilogram 1 meter second per second.

Shore 00

Using a durometer gauge, which uses a spring loaded steel rod to compress the surface to provide a reading. The Shore 00 Scale measures extremely soft materials like gels.

Shore C

The Shore C hardness is designed to measure the hardness of range of substrates materials such as foam and sponges.

Shore A

Using a durometer gauge, which uses a spring loaded steel rod to compress the surface to provide a reading. The Shore A scale measures a wide range of material types; from very soft and flexible to semi-rigid plastics with almost no flexibility at all.



The megapascal is a x1000000 multiple of the pascal unit which is the SI unit for pressure. 1 megapascal equals 1,000,000 pascals. Primarily used for higher range pressure measurement due to its larger value (e.g. 1 MPa = 10 bar), the MPa is mainly used to describe the pressure ranges and ratings of hydraulic systems



The Kilopascal is a unit of pressure, 1 kPa is approximately the pressure exerted by a 10-g mass resting on a 1-cm² area. 101.3kPa equals 1 atm (atmospheric pressure). There are 1000 Pascals in 1 Kilopascal.

Pores per Inch


PPI or Pores per inch designates the number of pores in one linear inch. Counting the pores is a visual indication of porosity which directly coincides with an airflow tested measurement that defines a range of airflow for a given porosity.

Pores per Centimetre


1 Kilogram/ cubic meter


The Kilogram per meter cubed is the standard unit of material density in the international System of Units (SI).

1 Kilogram/ per square



Kilogram per square Centimetre is a pressure unit that has been largely superseded by the SI unit of system of pascal units. It is the metric equivalent of pounds per square inch (psi). 1 kg/cm² equals 98,066.5 pascals.

Grams per square meter


g/m² simply means grams per square meter. This calculation is commonly used for nonwoven materials, paper, plastic and other thin materials.

Pounds per cubic foot



pcf is used for density which refers to how much one cubic foot of foam weighs. For example, a foam layer that weighs 100 pounds and measures 25 cubic feet has a density of 4 pcf; assuming the foam has a uniform consistency, every square foot of the layer will measure 4 pounds.

Kilo Newton


While a kg is a unit of mass, a KN is a unit of force.

Kilo Newton/ square metre


The Kilo Newton per square meter is a non SI unit for pressure. 1 KN/m² equals 1000 N/m². Pressure is defined as force per area and the SI unit for force is Newtons (N) and the SI unit for area is square meters (m²). 1 Newton per square meter equals 1 Pascal, therefore 1 KN/m² equals 1000 Pa.

International Rubber Hardness Degrees


International rubber hardness degress (IRHD) test method provides a highly repeatable measurement on rubber parts of various shapes and sizes. The distance between the two applied forces is measured and converted to an IRHD hardness value.




Density is defined as the mass per unit volume in air; it is measured by dividing the weight of a sample by its volume. Normally recorded in kg/m³ however the USA record theirs in lb/ft³ (to convert lb/ft³ to kg/m³, multiply the Lbs * 16). Some test methods used – ASTM D3574-91, BS4443, Din53420, ISO 845.



Mpa, N/mm, KN/M²

Tensile Strength kPa is defined as the maximum force reached at the point of rupture.



Elongation % is defined as the measurement of elongation at the rupture point.


Shore 00, C, A

Soft, Medium, Firm, Very Firm, IRHD

Indentation Load Deflection Hardness and Compression Deflection Hardness

Indentation Load Deflection Hardness


ILD is defined as the force required compressing a 380*380*50 mm piece of foam by 40% with a 200 mm diameter compression plate. Recorded in Newtons (N). Some test methods are BS4443 pt 2 method 7, ISO 2439 B.

Compression Deflection



CLD is defined as the force required compressing a 100*100*50 mm piece of foam with a 200 mm diameter compression plate. The foam is compressed three times to 70% and then after the third compression, readings are taken at 60%, 40% and 25%. Recorded in kPa. Some test methods are: DIN 53577, ISO 3386/1.

Water Absorption


Measurement of the absorption of water in a sample compressed and immersed in water for a given duration.

Cell Count & Structure


PPC, Very Fine, Fine, Medium

For more than 25 years, the cellular structure and the cell size have been defined by the unit “PPI” – Pores per inch. The number of pores is counted on a standard length of 1 inch, however the pore has never been clearly defined – it can be a window or the full section of the cells.

Flammability/ Heat Resistance

Flame behaviour is measured in different formulas – using a burner with calibrated flame, and also the behaviour of the foam irradiated by a radiator of 500 W for duration of 20 minutes.

Tear Resistance

Determination of the maximum forces at which the tear rupture takes place. Some test methods: ASTM D 3574/F.


Cell Type

Open cell, Closed cell, Semi-closed


Acoustic and sound insulation

Resistance to Oil, Acid and UV

Abrasive Resistant

Heat Resistant

Woven Weight


Abrasive Fibre

Abrasive Binder

Specific Gravity



Air Flow Resistance

Polyethylene Foam

Polyethylene Foam is produced through the Polymerization of Ethylene. It is available in lots of densities with varying material properties. This variety is created by using different catalysts and through Gas Blown and Chemically Blown processes. Polyethylene Foam is non-abrasive, a thermal insulator, inert to water, grease and solvents at typical temperatures, CFC free, ozone friendly and extremely lightweight.

Polyurethane Foam

Polyurethane is a resilient, flexible and durable material. It can be hard like fibreglass, squishy like upholstery foam or sticky like glue. Polyurethane is a term that covers two main groups; Polyether and Polyester, both of which encompass thousands of different grades and materials, all with their own unique properties.


Polyester foams have a number of characteristics in which make them ideal for a wide range of applications, advantages include; regular cell structure, accurate control of pore size, high air flow resistance and slow oxidation rate. Polyester also has a high level of absorbency through hydrophilic properties.