Frequently Asked Questions
What does the “Density” of foam mean?
What is “Indentation Force Deflection (IFD)”?
What is “Compression Load Deflection (CLD)”?
What is “% Compression Set”?
What is “Tensile Strength”?
What is “Elongation”?
What is “Tear Strength”?
What is “Clickability”?
What is a “Board Foot”?
What is “Reticulated” Foam?
Q: What does the “Density” of foam mean?
A: Density is the measurement of the mass of the foam in pounds per volume in cubic feet. So, density of foam is expressed in pounds per cubic feet. Density is not a measure of firmness, stiffness, pore size or load bearing capacity. If you cut a piece of foam that is supposed to have a density of 1.7 pounds per cubic foot (PCF) into a 12” x 12” x 12” block, it will weigh 1.7 pounds. Density can be obtained from any sample size.
Q: What is “Indentation Force Deflection (IFD)”?
A: Previously known as ILD, is one test method to determine load bearing capacity (firmness or stiffness) and is expressed in pounds of force per 50 square inches, at a given percent deflection of foam.
Q: What is “Compression Load Deflection (CLD)”?
A: CLD is also a measure of firmness and is expressed in pounds per square inch (psi), at a given percentage deflection.
Q: What is “% Compression Set”?
A: Percent compression set is a measure of the permanent deformation of foam after it has been compressed between two metal plates for a controlled time period and temperature condition. The standard conditions are 22 hours at 70o C (158o F). The foam is then compressed to a thickness given as a percentage of its original thickness, usually 50%. Compression set is expressed as the percentage of its original thickness that remained “set”. For example: If a 2” x 2” x 1” sample measured 1.00 inch before compression and 0.95 inch after the test, it is reported to have a compression set value of 5%, i.e., it did not recover 5% of its original thickness.
Q: What is “Tensile Strength”?
A: Tensile strength is the measure of the amount of force required to break a ½ square inch area of foam as it is pulled apart. Tensile strength is expressed in pounds per square inch (psi).
Q: What is “Elongation”?
A: Elongation is the measure of the extent to which the foam can be stretched before it breaks and is expressed as a percentage of its original length. Elongation is measured at the same time, as tensile strength is determined; therefore, the sample size is the same.
Q: What is “Tear Strength”?
A: Tear strength is a measure of the force required to continue a tear in foam after a split has been started and is expressed in pounds per linear inch (pli).
Q: What is “Clickability”?
A: This is the rating of a foam’s ability to recover from a die cutting operation. Foams are rated as having a good, fair or poor click property. Click is tested on a one inch piece of foam by die-cutting a tensile specimen and observing the initial recovery and then the recovery after one minute. What is observed is the sharpness of the edges of the tensile part and the one inch foam sheet it was cut from. Also, the height recovery after the compression of the die cutter is noted.
Q: What is a “Board Foot”?
A: Foam is measured in board feet. A board foot of foam is equal to a 12” x 12” x 1” piece of foam and is equal to 1/12 of a cubic foot of foam. This is the commonly used measure in the foam industry.
Q: What is “Reticulated” Foam?
A: Reticulated foam is 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. Reticulated foams are sometimes referred to as Filter foams.
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