What kind of filling for your sofa cushions?

12 05 2015


One thing that most people care about is how the cushions feel to them – do you like to sink down into the cushions or you like a denser, more supportive cushion? Either way, the cushions are important.

Before plastics, our grandparents filled cushions with feathers, horsehair, wool or cotton batting – even straw (one of the earliest stuffing materials). This stuff often shifted, meaning that you’d have to plump up the feathers, horsehair or batting to make the sofa look, and feel, good.  But with the advent of plastics, our lives changed.  Polyurethane foam was introduced as a cushion component in furniture in 1957 –  only a bit more than 55 years ago – and quickly replaced latex, excelsior, cotton batting, horsehair and wool because it was CHEAP and it behaved!  Imagine – polyfoam cushions at $2 vs. natural latex at $7 or $8.  Price made all the difference.  Today, Eisenberg Upholstery’s website says that “easily 25% of all furniture repairs I see deal with bad foam or padding. The point is: start with good foam and you won’t be sorry.”

Polyurethane foam for cushions are generally measured by two values:

  1. The density or weight per cubic foot. The higher the number, the more it weighs.   Foam that has a density of 1.8, for example, contains 1.8 lbs. of foam per cubic foot and foam that has a density of 2.5 would have 2.5 lbs of foam per cubic foot.  Density for sofa cushions ranges between 1.6 and 5 or even 6.
  2. The second measurement tells you the firmness of the foam  (called the IFD  – the Indentation Force Deflection). The IFD is the feel of the cushion, and tells you how much weight it takes to compress the foam by one third. The lower IFD will sit softer. The higher IFD will sit firmer.  IFD numbers range between 15 to 35.

What many people don’t realize is that the density and firmness numbers go hand in hand – you can’t look at one without the other.  They are expressed as density/firmness, for example: 15/30 or 29/52.  The first, 15/30 means that 1.5 pounds of foam per cubic foot will take 30 pounds of weight to compress the foam 33%.  The second example means that 2.9 pounds per cubic foot of foam will take 52 pounds of weight to compress the block 33%.

After choosing which foam to use, it is then wrapped with something to soften the edges – for example,  Dacron or polyester batting, cotton or wool batting or down/feathers.

Lowest quality sofas will not even wrap the (low quality) foam; higher quality sofas have cushions that are made from very high quality foam and wrapped in wool or down.  But as you will see, the foam is itself very problematic.

You will now commonly find in the market polyurethane foam, synthetic or natural latex rubber and the new, highly touted soy based foam.  We’ll look at these individually:

The most popular type of cushion filler today is polyurethane foam. Also known as “Polyfoam”, it has been the standard fill in most furniture since its wide scale introduction in the 1960’s because of its low cost (really cheap!).  A staggering 2.1 billion pounds of flexible polyurethane foam is produced every year in the US alone.[1]

Polyurethane foam is a by-product of the same process used to make petroleum from crude oil. It involves two main ingredients: polyols and diisocyanates:

  • A polyol is a substance created through a chemical reaction using methyloxirane (also called propylene oxide).
  • Toluene diisocyanate (TDI) is the most common isocyanate employed in polyurethane manufacturing, and is considered the ‘workhorse’ of flexible foam production.
  • Both methyloxirane and TDI have been formally identified as carcinogens by the State of California
  • Both are on the List of  Toxic Substances under the Canadian Environmental Protection Act.
  • Propylene oxide and TDI are also among 216 chemicals that have been proven to cause mammary tumors.  However, none of these chemicals have ever been regulated for their potential to induce breast cancer.

The US Environmental Protection Agency (EPA) considers polyurethane foam fabrication facilities potential major sources of several hazardous air pollutants including methylene chloride, toluene diisocyanate (TDI), and hydrogen cyanide.   There have been many cases of occupational exposure in factories (resulting in isocyanate-induced asthma, respiratory disease and death), but exposure isn’t limited to factories: The State of North Carolina forced the closure of a polyurethane manufacturing plant after local residents tested positive for TDI exposure and isocyanate exposure has been found at such places as public schools.

The United States Occupational Safety and Health Administration (OSHA) has yet to establish exposure limits on carcinogenicity for polyurethane foam. This does not mean, as Len Laycock explains in his series “Killing You Softly”, “that consumers are not exposed to hazardous air pollutants when using materials that contain polyurethane. Once upon a time, household dust was just a nuisance. Today, however, house dust represents a time capsule of all the chemicals that enter people’s homes. This includes particles created from the break down of polyurethane foam. From sofas and chairs, to shoes and carpet underlay, sources of polyurethane dust are plentiful. Organotin compounds are one of the chemical groups found in household dust that have been linked to polyurethane foam. Highly poisonous, even in small amounts, these compounds can disrupt hormonal and reproductive systems, and are toxic to the immune system. Early life exposure has been shown to disrupt brain development.”

“Since most people spend a majority of their time indoors, there is ample opportunity for frequent and prolonged exposure to the dust and its load of contaminants. And if the dust doesn’t get you, research also indicates that toluene, a known neurotoxin, off gases from polyurethane foam products.”

I found this on the Sovn blog:

“the average queen-sized polyurethane foam mattress covered in polyester fabric loses HALF its weight over ten years of use. Where does the weight go? Polyurethane oxidizes, and it creates “fluff” (dust) which is released into the air and eventually settles in and around your home and yes, you breathe in this dust. Some of the chemicals in use in these types of mattresses include formaldehyde, styrene, toluene di-isocyanate (TDI), antimony…the list goes on and on.”

Polyurethane foams are advertised as being recyclable, and most manufacturing scraps (i.e., post industrial) are virtually all recycled – yet the products from this waste have limited applications (such as carpet backing).  Post consumer, the product is difficult to recycle, and the sheer volume of scrap foam that is generated (mainly due to old cushions) is greater than the rate at which it can be recycled – so it  mostly ends up at the landfill.  This recycling claim only perpetuates the continued use of hazardous and carcinogenic chemicals.

Polyfoam has some hidden costs (other than the chemical “witch’s brew” described above):  besides its relatively innocuous tendency to break down rapidly, resulting in lumpy cushions, and its poor porosity (giving it a tendency to trap moisture which results in mold), it is also extremely flammable, and therein lies another rub!

Polyurethane foam is so flammable that it’s often referred to by fire marshals as “solid gasoline.” When untreated foam is ignited, it burns extremely fast. Ignited polyurethane foam sofas can reach temperatures over 1400 degrees Fahrenheit within minutes. Making it even more deadly are the toxic gasses produced by burning polyurethane foam –  such as hydrogen cyanide. The gas was also implicated in the 2003 Rhode Island nightclub fire that killed 100 people, including Great White guitarist Ty Longley, and injured more than 200 others. Tellingly, a witness to that fire, television news cameraman Brian Butler, told interviewers that “It had to be two minutes, tops, before the whole place was black smoke.”   Just one breath of superheated toxic gas can incapacitate a person, preventing escape from a burning structure.

Therefore, flame-retardant chemicals are added to its production when it is used in mattresses and upholstered furniture.   This application of chemicals does not alleviate all concerns associated with its flammability, since polyurethane foam releases a number of toxic substances at different temperature stages. For example, at temperatures of about 800 degrees, polyurethane foam begins to rapidly decompose, releasing gases and compounds such as hydrogen cyanide, carbon monoxide, acetronitrile, acrylonitrile, pyridine, ethylene, ethane, propane, butadine, propinitrile, acetaldehyde, methylacrylonitrile, benzene, pyrrole, toluene, methyl pyridine, methyl cyanobenzene, naphthalene, quinoline, indene, and carbon dioxide.

According to the federal government’s National Institute of Standards and Technology, polyurethane foam in furniture is responsible for 30 percent of U.S. deaths from fires each year.

In conclusion, the benefits of polyfoam (low cost) is far outweighed by the disadvantages:  being made from a non-renewable resource (oil),  and the toxicity of main chemical components as well as the toxicity of the flame retardants added to the foam – not to mention the fact that even the best foams begin to break down after around 10 – 12 years of “normal use”.[2] The fact that California has amended the old law that required fire retardants in polyurethane foam doesn’t affect the fact that in a fire, the toxic gasses released by the foam (such as hydrogen cyanide) would incapacitate the occupants of a house in just a few minutes.

The newest entry in the green sweepstakes is what’s called a bio-based foam made from soybeans. This “soy foam” is highly touted as “A leap forward in foam technology, conserving increasingly scarce oil resources while substituting more sustainable options,” as one product brochure describes it. Companies and media releases claim that using soy in polyurethane foam production results in fewer greenhouse gas emissions, requires less energy, and could significantly reduce reliance on petroleum. Many companies are jumping on the bandwagon, advertising their green program of using foam cushions with “20% bio based foam” (everybody knows we have to start somewhere and that’s a start, right?).  As Len Laycock,  CEO of Upholstery Arts (which was the first furniture company in the world to introduce Cradle to Cradle product cycle and achieve the Rainforest Alliance Forest Stewardship Council Certification),  says  – who wouldn’t sleep sounder with such promising news?   (I have leaned heavily on Mr. Laycock’s articles on poly and soy foam, “Killing You Softly”, for this post.)

As with so many over hyped ‘green’ claims, it’s the things they don’t say that matter most.  While these claims contain grains of truth, they are a far cry from the whole truth. So called ‘soy foam’ is hardly the dreamy green product that manufacturers and suppliers want people to believe. To begin, let’s look at why they claim soy foam is green:

  • it’s made from soybeans, a renewable  resource
  • it reduces our dependence on fossil  fuels  by  both reducing the amount of fossil fuel needed for the feedstock  and  by reducing the energy requirements needed to produce the foam.

Are these viable claims?

It’s made from soybeans, a renewable resource:  This claim is undeniably true.   But what they don’t tell you is that this product, marketed as soy or bio-based,  contains very little soy. In fact, it is more accurate to call it ‘polyurethane based foam with a touch of soy added for marketing purposes’. For example, a product marketed as “20% soy based” may sound impressive, but what this typically means is that only 20 % of the polyol portion of the foam is derived from soy. Given that polyurethane foam is made by combining two main ingredients—a polyol and an isocyanate—in approximately equal parts, “20% soy based” translates to a mere 10% of the foam’s total volume. In this example the product remains 90% polyurethane foam and by any reasonable measure cannot legitimately be described as ‘based’ on soy. If you go to Starbucks and buy a 20 oz coffee and add 2-3 soy milk/creamers to it, does it become “soy-based” coffee?

It reduces our dependence on fossil fuels: According to Cargill, a multi-national producer of agricultural and industrial products, including BiOH polyol (the “soy” portion of “soy foam”), the soy based portion of so called ‘soy foam’ ranges from  5% up to a theoretical 40% of polyurethane foam formulations. This means that while suppliers may claim that ‘bio foams’ are based on renewable materials such as soy, in reality a whopping 90 to 95%, and sometimes more of the product consists of the same old petro-chemical based brew of toxic chemicals. This is no ‘leap forward in foam technology’. It is true that the energy needed to produce soy-based foam is, according to Cargill, who manufactures the soy polyol,  less that that needed to produce the polyurethane foam.  But the way they report the difference is certainly difficult to decipher:  soy based polyols use 23% less energy to produce than petroleum based polyols, according to Cargill’s LCA.   But the formula for the foam uses only 20% soy based  polyols, so by my crude calculations (20% of 50%…) the energy savings of 20% soy based foam would require only 4.6%  less energy than that used to make the petroleum based foam.  But hey, that’s still a savings and every little bit helps get us closer to a self sustaining economy and is friendlier to the planet.

But the real problem with advertising soy based foam as a new, miracle green product is that the foam, whether soy based or not, remains a “greenhouse gas spewing pretroleum product and a witches brew of carcinogenic and neurotoxic chemicals”, according to Len Laycock.

My concern with the use of soy is not its carbon footprint but rather the introduction of a whole new universe of concerns such as pesticide use, genetically modifed crops, appropriation of food stocks and deforestation.  Most soy crops are now GMO:  according to the USDA, over 91% of all soy crops in the US are now GMO; in 2007, 58.6% of all soybeans worldwide were GMO.  If you don’t think that’s a big deal, please read our posts on these issues (9.23.09 and 9.29.09).  The debate still rages today.  Greenpeace did an expose (“Eating Up The Amazon”) on what they consider to be a driving force behind Amazon rainforest destruction – Cargill’s race to establish soy plantations in Brazil.

In “Killing You Softly“, another sinister side of  soy based foam marketing is brought to light:

“Pretending to offer a ‘soy based’ foam allows these corporations to cloak themselves in a green blanket and masquerade as environmentally responsible corporations when in practice they are not. By highlighting small petroleum savings, they conveniently distract the public from the fact that this product’s manufacture and use continues to threaten human health and poses serious disposal problems. Aside from replacing a small portion of petroleum polyols, the production of polyurethane based foams with soy added continues to rely heavily on ‘the workhorse of the polyurethane foam industry’, cancer causing toluene diisocyanate (TDI). So it remains ‘business as usual ‘ for polyurethane manufacturers.”

Despite what polyurethane foam and furniture companies imply , soy foam is not biodegradable either. Buried in the footnotes on their website, Cargill quietly acknowledges that, “foams made with BiOH polyols are not more biodegradable than traditional petroleum-based cushioning”. Those ever so carefully phrased words are an admission that all polyurethane foams, with or without soy added, simply cannot biodegrade. And so they will languish in our garbage dumps, leach into our water, and find their way into the soft tissue of young children, contaminating and compromising life long after their intended use.

The current marketing of polyurethane foam and furniture made with ‘soy foam’ is merely a page out the tobacco industry’s current ‘greenwashing’ play book. Like a subliminal message, the polyurethane foam and furniture industries are using the soothing words and images of the environmental movement to distract people from the known negative health and environmental impacts of polyurethane foam manufacture, use and disposal.

Cigarettes that are organic (pesticide-free), completely biodegradable, and manufactured using renewable tobacco, still cause cancer and countless deaths. Polyurethane foam made with small amounts of soy derived materials still exposes human beings to toxic, carcinogenic materials, still relies on oil production, and still poisons life.

So what’s a poor consumer to do?  We think there is a viable, albeit expensive, product choice: natural latex (rubber). The word “latex” can be confusing for consumers, because it has been used to describe both natural and synthetic products interchangeably, without adequate explanation. This product can be 100% natural (natural latex) or 100% man-made (derived from petrochemicals) – or it can be a combination of the two – the so called “natural latex”. Also, remember latex is rubber and rubber is latex.

  • Natural latex – The raw material for  natural latex comes from a renewable resource – it is obtained from the sap of the Hevea Brasiliensis (rubber) tree, and was once widely used for cushioning.  Rubber trees are cultivated, mainly in South East Asia,  through a new planting and replanting program by large scale plantation and small farmers to ensure a continuous sustainable supply of natural  latex.  Natural latex is both recyclable and biodegradeable, and is mold, mildew and dust mite resistant.  It is not highly  flammable and does not require fire retardant chemicals to pass the Cal 117 test.  It has little or no off-gassing associated with it.    Because natural rubber has high energy production costs (although a  smaller footprint than either polyurethane or soy-based foams [3]),  and is restricted to a limited supply, it is more costly than petroleum based foam.
  • Synthetic latex – The terminology is very confusing, because synthetic latex is often referred to simply as  “latex” or even “100% natural latex”.  It is also known as styrene-butadiene rubber  (SBR).   The chemical styrene is  toxic to the lungs, liver, and brain; the EPA finds nervous system effects such as depression, loss of concentration and a potential for cancer(4).  Synthetic additives are added to achieve stabilization.    Often however, synthetic latex  can be made of combinations of polyurethane and natural latex, or a  combination of 70% natural latex and 30% SBR.  Most stores sell one of these versions under the term “natural latex” – so caveat emptor!    Being  petroleum based, the source of supply for the production of  synthetic latex is certainly non-sustainable and diminishing as well.

Natural latex is breathable, biodegradeable,  healthier (i.e., totally nontoxic, and mold & mildew proof) and lasts longer than polyfoam – some reports say up to 20 times longer.


[1] DFE 2008 Office Chair Foam;  http://en.wikiversity.org/wiki/DFE2008_Office_Chair_Foam#Basics

[2] http://www.foamforyou.com/Foam_Specs.htm

[3] Op cit., http://en.wikiversity.org/wiki/DFE2008_Office_Chair_Foam#Basics

(4) Technical Fact Sheet on: Styrene; Environmental Protection Agency; http://www.epa.gov/ogwdw/pdfs/factsheets/voc/tech/styrene.pdf