Polyurethane Foam is one of the primary products used in most mattresses. It is used not only in solid foam core mattresses, but as comfort and support layers in innerspring mattresses. Prior to the US government implementing the cigarette burn standards in the early 70's mattress manufacturers used materials such as cotton felt, sisal and coconut fiber more than polyurethane foam. Polyurethane used under the surface ticking offered a much better solution to ignition resistance to cigarettes being placed on the surface of mattresses, a requirement of CFR 1632 burn tests. In addition, polyurethane was cleaner and offered very good comfort benefits improving the feel and performance of bedding products. In the years since that time many new types of polyurethane foams have been developed. Viscoelastic, high resilience and quilting foam such as Quiltflex are now intricate component parts improving performance as well as differentiation in mattresses.

According to the Polyurethane Association: Flexible polyurethane foam (FPF) is a chemically complex polymeric product having a broad range of load bearing capability and resiliency, offering comfort as cushioning material for furniture, bedding, carpet underlay, and automotive interiors. FPF also offers protective shock absorption performance for use in packaging and automotive applications.   In furniture and bedding applications, short staple polyester fiber is often used instead of FPF, as is cotton, but both alternative materials have poor height recovery characteristics after compression. Steel springs also recover well but must be insulated from the user with some type of cushioning material. Comparing FPF to alternative materials in the areas of economics, comfort potential, ease of use, and durability, there is not an acceptable substitute for FPF.

Polyurethane foam is made by mixing   polyols , TDI , catalysts, blowing agents and other additives and allowing the resulting foam to rise via reaction into large buns that will be as large as 8 ft. x 8 ft. x 60 ft. Most polyurethane foam is manufactured using continuous processing or pouring lines that produce these large buns as they exit the conveyor at the end of the pouring line. The foam buns are either cut into mattress core sizes, mattress topper sizes or run through a loop slitter in order to produce rolls for mattress quilting.

The most common polyurethane types used in the bedding production are conventional urethanes in density range of 1.2 lb to 1.8 lb. Density equates to weight of the foam. 1.2 lbs per square foot means exactly that-a 12” x 12” x 12” will weigh 1.2 pounds. The other measurement that is most commonly used measures compression or hardness or softness of the foam. It is referred to as ILD (Indention Load Deflection) or IFD (Indention Force Deflection). IFD or ILD is a measure of the load bearing capacity of polyurethane foam. IFD is generally measured as the force (in pounds) required to compress a 50 square inch circular disc 1” into a 4” thick sample.

Different foam densities can have the same IFD measure without having the same support factor. Support factor is measured by taking a second IFD rating at 65% compression with the same exact sample and disc. The 65% IFD rating is divided by the 25% IFD rating, the higher the number represents support of the polyurethane foam. This shows that higher density foams offer superior deep down support while lower density foams tend to bottom out with little deep down resistance. Higher density foams will require more force than lower density foams, thus showing higher density foams offering more support. Higher density foams are more costly, so many bedding manufacturers make the mistake of assuming that lower density foams perform identical to higher density foams due the fact that both have the same IFD rating.

Another characteristic of polyurethane foam is the IFD measure lowering after compression. This is called hysteresis   which is 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. Hysteresis values may provide a good indication of overall flexible foam durability. Low hysteresis in conventional foam is equal to less IFD loss. Generally, the lower the density of the foam the greater hysteresis, meaning that lower cost lower density polyurethane foams lose their original feel after being compressed over time by the weight of the sleeper compressing the layers of polyurethane foam. This is a good measure of durability of the polyurethane foam. In higher density foams strong polymer bonds are formed which enable the foam to maintain firmness and support. Lower density foams have weaker polymer bonds with the addition of more hydrogen bonds that tend to break down quickly completely changing the feel of the foam.

The primary chemical components of producing polyurethane foam are TDI (toluene diioscyanate), polyol, catalyst (to control the chemical reaction of TDI and polyol)  and water (as a blowing agent). Blowing is the process by which flexible polyurethane is foamed during production. In all cases, blowing occurs when water and TDI react to form CO2. The CO2 process is used by most polyurethane manufacturers today. Formerly, auxiliary blowing agents were used, many of which have been banned because of their effect on the environment. These auxiliary blowing agents were used as an additive 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 were methylene chloride, acetone, hydrochlorofluorocarbons (CFCs), and isopentane.

Improvements in the CO2 process have made the use of these auxiliary blowing agents obsolete and unnecessary in polyurethane production. The one exception to this is Variable Pressure Foaming technology which is used by Foamex exclusively in the US . Variable Pressure Foaming (VPF) technology is a pouring line completely done in an enclosed vacuum. This enables Foamex to use auxiliary blowing agents, then recapturing them without releasing them into the atmosphere. Foamex claims this enables them to produce polyurethane foams to more precise densities and IFDs.

This is what Foamex says about their proprietary VPF process … We are committed to environmentally responsible manufacturing. We have made significant progress in the reduction of hazardous air emissions and VOCs, which many of our competitors continue to utilize in their production processes. Our patented Variable Pressure Foaming Technology sets the standard in environmentally responsible foam manufacturing. In fact, VPF SM   is the most environmentally friendly process for the manufacture of polyurethane foams worldwide. VPF SM   enables us to develop and produce unique, value-enhancing products for our customers, while providing higher yields from raw materials than traditional foaming methods. This combination of superior product performance and reduced air emissions provides an important technological edge for FXI. Compared to standard foam production methods, VPF SM   technology exceeds the Clean Air Act Requirements. The most beneficial advantage of the VPF SM   manufacturing process is that the physical properties of the polyurethane foam can be controlled through the use of air pressure.

Foamex has used this technology to produce Quiltflex , one of the most innovative new products developed for an alternative to polyester fiber and conventional low density supersoft foams. It has better performance and durability and is not subject to compression set. Compression set   is 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". High loft polyester fiber is subject to compression set as well, due to the fibers becoming matted down flat as opposed to being upright when the high loft polyester is quilted into the mattress panel.

Competitors of Foamex such as Carpenter, Flexible and Hickory claim advances in the CO2 process have enabled them to produce polyurethane foam that is equal to if not better than Foamex's VPF technology.

From Carpenter's website… Natural Foam Technology™ (NFT) process to our Comfort Cure™ products using our foam conditioning system, Richfoam™ products are used in almost every aspect of furniture production. NFT uses CO2 as a natural blowing agent to make the foam expand. Carpenter Co. has made it our number one priority to produce materials using manufacturing techniques that will not harm our environment. CO2, better know as Carbon Dioxide, is a natural occurring gas that is released into the atmosphere as we breathe. Plants use carbon dioxide to begin the photo-synthesis process whereby they sustain their life. There's not a more natural way to produce foams in the marketplace today. Our Comfort Cure™ foams are conditioned by pulling air through recently poured foams to rapidly cool the foam. This eliminates the effects of heat and humidity on the foam which can cause inconsistencies within the product. Comfort Cure™ foams are able to meet stringent IFD specifications that had only been attainable in High Resiliency foams in the past.

The beauty of products such as Foamex's Quiltflex and Carpenter's Hypersoft products are their application for Quilting foams that offer the combination of higher densities and lower IFD's. Carpenter's Hypersoft offers densities in the 1.1 range with IFD's in the 9-10 range with little if any compression set associated with traditional supersoft quilting foams.

When designing many of today's pressure relieving mattresses these types of products offer very good pressure relieving characteristics. Many mattress designs today are engineered to offer surface pressure relief with these types of polyurethane foam while offering good support deeper down in the mattress with higher density firmer IFD foams for intermediate support in the case of innerspring mattresses. Even all foam mattresses containing latex or high density polyurethane core mattresses can be made softer on the surface with these new surface pressure relieving types of foam.

In mattress design the goal of comfort layers of polyurethane foam on the surface is for a more body conforming surface feel combined with greater support layer foams in the intermediate layers that actually firm up and support the body as the sleeper conforms into the mattress. Most foam with the exception of viscoelastic (memory) foams is very resilient. R esilience   is 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.

Viscoelastic foam is typified by its slow recovery after compression. When the person lying on this type of foam, the foam conforms and molds to their body. After the weight of their body is removed from the foam, the foam slowly reassumes its original shape. Viscoelastic foam is extremely shock absorbing and has the ability to limit motion across the surface of the mattress. This is typically referred to motion transfer. As compared to conventional polyurethane or latex foams it is about 1/3 as resilient. Iother words it is not very bouncy, which can be an attribute for those bother by sleeping surface motion disturbance.

It is also important to make the distinction between polyurethane foam and latex foam. Latex foam is a natural rubber product which is not related to polyurethane foam. Latex foam is a vulcanized product usually made in a vacuum molded process using natural latex sap ( hevea brasiliensis tree) , synthetic latex ( S tyrene-Butadiene-Rubber   ( SBR ) is a   synthetic rubber copolymer   consisting of   styrene   and   butadiene) or a blend both natural and synthetic latex. Latex is produced either in the Dunlop process or the Talalay process. Dunlop process latex is typically used for 100% natural latex cores, toppers and pillows and tends is denser and firmer finished latex product. Talalay latex is a process that uses extreme heat and extreme cold during vulcanization that can produce softer lower IFD latex cores, toppers and pillows. Most Talalay is blended with natural and synthetic latex, however there is 100% natural Talalay available as well. Many of today's latex mattresses use a combination of both with pressure relief coming from softer Talalay on the surface of the mattress with support coming from firmer Dunlop process cores in all latex constructions. Latex is also being used as comfort and support layers in many innerspring mattresses and is even being used in combination with conventional polyurethane as well as viscoelastic foams.

Another development is the use of vegetable based polyols in the process of making conventional polyurethane as well as viscoelastic foam. These foams are at best 10-15% vegetable based polyol with the balance typical petroleum based TDIs and polyol.

In conclusion there are many choices for bedding manufacturers in the market today. With the tremendous rise in petroleum based polyurethanes, many companies are being forced to downgrade the quality of polyurethanes used in mattresses today. That is why it is more challenging than ever to educate consumers as to the value and benefit of using some of the more sophisticated polyurethane and latex available on the market today. The temptation for manufacturers is to use cheaper less durable foams to achieve price competitiveness. There is a large risk here, since consumers cannot be fooled by these compromises made by bedding manufacturers for very long. In other words when consumers realize that the new mattress they recently purchased fails to hold up and loses it comfort performance, it may well come back to haunt those manufacturers who compromised the quality of their products by substituting cheaper poorer performing components. There is much evidence of these compromises being made, by the greater use of lower quality lower density polyurethane foams being used in mattresses today. Polyurethane foams as low as .8 lb – 1 lb density foams are being used in many mattresses today. These foams are formed with very weak polymer bonds and are mostly made up of foams formed with weak hydrogen bonds which will lose more than half of their IFD rating very shortly. Also, these foams are subject to compression set or collapse, bringing about massive body impressions in new mattresses in a very short period of time. It is very important for all legitimate bedding manufacturers to understand the destructive effects to the bedding products they are putting their reputation on. A better understanding of this very important component will not only enable manufacturers to build superior products, but also build better more durable products for their customers.

There are those who claim their fire barriers to be 100% natural, which is also misleading. Blended wool with inherent rayon is also touted sometimes as 100% natural. However this is not entirely true either. In the production of rayon, purified cellulose is chemically converted into a soluble compound. A solution of this compound is passed through the spinneret to form soft filaments that are then converted or “regenerated” into almost pure cellulose. Because of the reconversion of the soluble compound to cellulose, rayon is referred to as a regenerated cellulose fiber. During the extrusion process silica is chemically bonded to regenerated cellulose giving the finished product inherent flame retardancy . The chemical compound silicon dioxide , also known as silica (from the Latin silex ), is an oxide of silicon with a chemical formula of Si O 2 and has been known for its hardness since antiquity. Silica is most commonly found in nature as sand or quartz , as well as in the cell walls of diatoms . It is a principal component of most types of glass and substances such as concrete . Silica is the most abundant mineral in the earth's crust . It is not a stretch to describe regenerated cellulose and silica as natural, however the chemisty in order to produce the final product is not necessarily kind to the environment.

In conclusion 100% pure wool processed properly will perform very well as a FR barrier for CFR 1633 compliance. However it is a very expensive way to achieve it. Ultimately bedding manufacturers and their customers must decide whether it is worth the additional expense they must pay for an all natural solution for compliance to the law.