The following is a list of terms used in the futon and mattress industry.
Air Flow - The air flow test measures the ease with which air passes through a foam. It is an excellent measure of the overall efficiency with which the foam was produced…should be at least 2.0 cubic feet per minute.
Ball Rebound - a lab test to measure surface resiliency. A steel ball is dropped from a fixed height and the percentage of the ball rebound determines the resilience value.
Boardy - an undesirable stiff surface feel is observed in low density foam with high 25% IFD values.
Bottom Out - a lack of support under full weight load (often found in low density foam).
Breathability - see air flow
Comfort Factor - see support factor
Compression Set - foam with poor compression set (above 15%) will exhibit an undesirable occurrence …"taking a set", or a noticeable permanent surface depression. Foam cushioning can be tested for a compression set in the lab by squeezing a foam sample to 90% of its thickness and holding it in that compressed position at above average temperatures for 22 hrs (foam should have a CS of 10% or less).
Convoluted - a foam fabrication process involving special cutting equipment to produce a foam sheet with deep "egg carton" dimples.
Density - The weight of a cubic foot of foam. Density is independent of firmness, but is an important indicator of overall foam quality. The higher density virgin foam cores tend to have better surface softness.
Dish - an undesirable characteristic common with four and five inch thick low-density mattress cores. When weight is placed in the center of a low-density foam mattress, the corners rise and bow in response to the deep compression. The higher the density, the less the dish effect.
Fatigue (Flex Fatigue) - a softening or loss of load bearing capacity. It is measured by repeatedly compressing a foam sample and measuring the change in IFD. FYI…higher density, better quality foam will experience fatigue loss at 15% or less.
Filled Foam - the addition of inorganic fillers, such as marble dust, clay, etc. to increase the density; the additional fiber can reduce the "dish" effect. Fillers that give weight to high-density foam can increase the support factor (keep in mind filled polyurethane foam may be a poor substitute for higher density foam…lower quality filled foam tends to have less resiliency, strength, and durability.
Finger Nail - occurs when a foam core has been improperly produced. This happens more often with foam densities under 1.8 pounds per cubic foot. Can be simply tested by pressing a finger nail into a foam sample; a definite impression that does not quickly disappear indicates the foam will be boardy and have a stiff surface feel.
Hand - is the feel of the foam as the hand is rubbed lightly over the surface. A boardy (rough to the touch) feel has a poor hand. Foam with a velvet feel has good hand.
Hardness Ratio - see support factor
High Resilience (Hr) - a premium variety of polyurethane foam produced using a blend of polymer or graft polyols. HR foam's cell structure is different than other products which results in a cushioning material that is more supportive, comfortable, and durable. HR foams have a high support factor-which describes the feeling of surface comfort and deep down support.
Hysteres - the ability of foam to "push back" and provide a firm and supportive feel. Hysteresis is the ratio of the 25% IFD measured as a compression tester returns to normal position to the 25% IFD during compression. FYI - higher hysteresis values or less IFD loss are desirable.
IFD (Indentation Load Deflection) - is a measure of load bearing capacity or firmness. IFD is usually measured on the surface as 25% IFD, and under full load bearing conditions as 65% IFD. The number of pounds required to achieve 25% compression by the 50 sq in indicator foot is the 25% IFD value. The 65% IFD reading is obtained the same way at a deeper compression. Mattress readings range from 25-40 pounds; furniture cushions range from 10-40 IFD. The higher the IFD, the firmer the feel.
ILD (Indentation Load Deflection) - see IFD
Instron - this is a popular brand of universal testing apparatus.
Lamination - a fabrication process which bonds one foam variety to another using durable adhesives, basically used to obtain different combinations of support.
Latex - a natural foam rubber product which is not related to polyurethane foams.
Loaded - see filled foam Molded- foam chemicals are poured into a mold to form a cushion or mattress core with unique surface contours. Usually doesn't affect the performance of foam, but can visually enhance a product line.
Polymeric - see high resilience
Reinforced - see filled foam
Resiliency - a surface liveliness and spring-back ability. Measured in the lab with a resilience or ball rebound test. A steel ball is dropped onto the foam sample from a fixed height. Resilience is expressed as a percentage of ball rebound against the original height of the ball drop. A boardy foam will have a low resilience. Foam cushioning resilience values range from 40-75%
Sac Factor - see support factor
Sag Factor - see support factor
Shiners - light reflected from intact cell walls in the foam; these are noticed on cut surfaces on foam. Too many shiners indicate a foam that has to many closed cells and therefore would have a poor airflow value. They result from too much catalyst during the foam production.
Support Value - The ratio of 65% IFD divided by 25% IFD; the higher the number, the greater the difference between the surface firmness and the deep down support. Support factor is the best means of measuring comfort for comparison purposes. Higher support factors indicate desirable surface softness and firm inner support. SF should range from 1.6-3.0