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Merryweather Foam Blog

Since 1948, we have been industry leaders in fabricating unique, foam components for customers in the medical, sound absorption, automotive, and unique packaging industries. At Merryweather Foam, we pride ourselves on our ability to combine experience, innovation, and excellent customer service. We have the knowledge, manpower & equipment to help you get the job done. Visit our website to see our fabrication portfolio as well as our capabilities.

PORON: When Fire is a Possibility

Many types of foam burn rapidly. Some even drip burning material on to the surface below, helping a fire spread rapidly. However, there are foams formulated to provide high levels of fire resistance. Whenever possible these should be used near potential sources of ignition.

The fire-resistance of foam for use in appliances, enclosures and equipment is measured by testing to procedures set out in the UL94 standard. (Note: this does NOT address foam used in upholstery or building construction.) Flammability (the ease with which a material burns,) is shown by a UL94 rating, such as the UL94 V-0 indication carried by PORON® 4701-V0-M.

Foam Flammability
Anything composed of carbon and hydrogen will burn if conditions are right, and that means having oxygen and an ignition source. All foams are formed from these elements and oxygen is always present in the atmosphere, so to start a fire all that's needed is an ignition source. This could be provided by an electrical spark, such as when motors or relays produce arcing. High temperatures, as caused by friction between moving parts or electrical current flowing through wiring are others possible causes.

UL94 flammability ratings
The UL organization is an independent global testing organization dedicated to improving safety. Founded in 1894 as "Underwriters Electrical Bureau" it started out by testing noncombustible insulation material and grew to become first "Underwriters Laboratories" and now just UL.

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Using Rogers PORON Medical® Urethane Foams

Next time you leave wet footprints on a dry floor notice how little of your sole actually contacts the surface. It's mainly just the heel and the area in front of your toes. In most people those parts are well-padded, but diseases like diabetes reduce that cushioning, and painful ulcers can result. The solution is to increase the load-bearing area under the foot, and that's a perfect application for PORON Medical® urethane foam.

Flexible urethane foam has many uses, from mattresses and pillows to gaskets in household appliances. Most of these applications don't place great demands on how the foam performs, but medical applications are different. Whether used for wheelchair cushions, shoe inserts or wrist rests, foam for medical uses must be durable, compression set-resistant, and consistent from batch-to-batch.

Rogers PORON Medical® urethane foams are specially formulated to meet these challenging requirements. For a better understanding of their special properties this blog post addresses:

  • How Urethane Foam is Made
  • Flexible Foam Fabrication
  • Foam Properties
  • Medical Applications
  • Characteristics of PORON Medical® Foam

How Urethane Foam is Made
When a polyol, (a compound of oxygen and hydrogen atoms) is mixed with isocyanate, (a compound of oxygen, nitrogen and carbon) and water, they react immediately, producing polyurethane and carbon dioxide gas. The process is similar to baking dough into bread, with the gas creating bubbles or pores in the material as it sets. Additives like surfactants and filler materials influence hardness, pore size and distribution, and with very precise control it's possible to create foam with predictable properties and uniform small pores. In the case of PORON®, those pores are around 100 microns in size.

Making PORON® foam starts with creating a polyurethane 'froth' that gets deposited onto a moving web or belt. A gate controls the height of the froth, allowing a thin layer through to heating and then cooling stages before being coiled up on a roll for transport.

Flexible Foam Fabrication
Urethane foams like PORON Medical® foam can be fabricated several different ways. Shapes are cut from thin sheets using steel rule dies, thicker sheets are cut by waterjet cutter. Many different pressure sensitive adhesives can also easily be applied to urethane foams.

Foam Properties
Polyurethane foam is usually specified in terms of density. This is referenced in terms of the weight in pounds of a cubic foot. Denser foam supports greater loads and retains its properties better over time. However, density does not necessarily equate to firmness.

Firmness describes how much load it takes to compress a piece of foam material. The actual measurement used is Indentation Force Deflection (IFD). IFD testing, (standardized in ASTM D3574) involves placing a disk on the foam and increasing the load until a target level of compression is achieved.

The most widely quoted measure of firmness is 25% IFD, This is the load required to compress the material to 25% of it's free or unloaded height. Foam with a low IFD number is easily compressed, so feels softer than one with a higher number.

"Resilience" or surface feel describes the springiness of a foam material. In a foam pillow low resilience is desirable while people usually expect more springiness in their seat cushions. Resilience is determined by a foam's formulation and is calculated by dropping a ball onto the surface. A material causing a rebound less than 40% of the drop height is considered to have a "dead" feel.

Tensile strength, tear strength and elongation are all important performance measures. Foams that tear easily and are difficult to handle tend not to make durable support products and create considerable waste for their manufacturers. The ASTM D3574 standard provides methods for testing for tensile strength, tear strength and elongation.

Medical Applications
Foam is used in many ways in medicine, from medical device packaging to wound control. For PORON® foam the principal application is to provide support. A few of the places you might find PORON Medical® foam are:

  • Wheelchair seat cushions, where users not only need comfort over extended periods but also benefit from the increased stability contoured polyurethane foam provides.
  • Orthotic inserts, which provide relief from diabetes-induced ulcers through load spreading and impact cushioning. One study found PORON® provided superior dampening and durability to other cushioning materials, especially when bonded to a second material that resists shear forces.
  • Running injuries - a study published in the British Journal of Sports Medicine showed that polyurethane running shoe inserts provided relief from chronic running-induced injuries.
  • Bed Cushions, which prevent pressure ulcers, commonly called bed sores, by distributing pressure away from bone protrusions.
  • Prosthetic devices, where they improve comfort for amputees.
  • Slings & ankle supports, also to improve comfort.
  • Wrist Rests, to provide support
  • Head Restraints, providing cushioning to protect against vibration or impact forces.

Special Characteristics of PORON Medical® Foam
Rogers Corporation developed PORON® as an exceptionally elastic yet also highly predictable material. With an open structure porous structure it has excellent recovery characteristics and low compression set values. It has good resistance to solvents along with low outgassing, which means less odor than other foams. Being flame retardant, it's also good in situations where fire is a possibility.

Rogers Corporation makes three types of PORON Medical® foam, plus a related product, DermaBak®, a skin care material designed for use in the backings of wound dressings. PORON Medical® is available as:

  • PORON Medical® Urethane - Firm
    This is an open cell material made in densities from 15 to 20 pounds with 25% IFD in the range 6 – 25 psi. Its formulation makes it suitable for applications where energy absorbency is needed.
  • PORON Medical® Urethane - Slow Recovery
    Formulated for low resilience, which means a very slow rebound after compression, this is ideal for creating a custom fit after compression. Density is 15 pounds and the material comes in four grades of firmness with 25% IFD numbers ranging from 0.3 – 22 psi.
  • PORON® Medical® Urethane – Soft
    Available in 15 and 20 pound formulations with 25% IFD ranging from 4 - 14 psi, this versatile material is suitable for most cushioning applications.

Superior Performance
Depending on formulation and pore size, most open cell foam provides some degree of cushioning. However, low compression set resistance and poor durability render them inadequate for many medical applications. PORON Medical® foam is specially formulated to have a uniform structure of very small pores along with excellent compression set resistance. That results in predictable, and durable performance, making them the preferred choice when injury or disability necessitates cushioning. Whether the need is for a stable wheelchair seat or a long-lasting, pressure-relieving shoe insert, PORON Medical® foam should be a first choice. Have questions or would you like to schedule a call to discuss more? Please contact us today! 

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Advanced Cushioning & Gasketing with PORON® Urethanes

PORON® Urethane foams from Rogers Corporation offer high performance solutions that help solve a variety of industry problems. Serving a range of markets, from mobile communications to automotive to more general industrial needs, PORON® Urethane foams exceed performance expectations from one use to the next. Whether sealing against dust, managing vibrations, or providing impact protection, PORON® Urethanes can help.

With an impressive catalog of options, Rogers' PORON® Urethane foams are available in a wide range of thickness options. In addition to performance within an application, PORON® Urethane materials are also easy to fabricate. And while features such as excellent compression set resistance, low outgassing, and good chemical resistance are important, Rogers' materials provide peace of mind. With proprietary technology and a thorough understanding of the markets they serve, Rogers engineers its materials with the end use in mind. But with materials of this quality, "end" is not a word they use very often. Visit our materials page for more information on PORON® or please contact us and we would be happy to help you.

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The ViaBuff: A Skincare Exfoliation Product Made with Polyurethane Foam

ViaBuff Skin Physical Exfoliator
Exfoliation isn't a short term fad--it's crucial to maintain healthy looking skin. Exfoliation removes dead skin cells and debris that lurks on the outer layers of skin, and which can potentially clogged pores if left alone. Even better, exfoliation encourages cell renewal and healthy growth so that your beautiful and glowing skin can continue to shine. Exfoliating properly can be a precarious endeavor – scrubbing just a little bit too vigorously or using a strong exfoliating cream can further dehydrate the skin and cause outbreaks of inflammation. but foregoing exfoliation can leave the skin dried out and congested with dead skin cells and bacteria. That's why using a puff custom designed for the skin, like the ViaBuff, is so important. Most people with normal skin types should exfoliate once to twice a week. Those with oily skin may need to do so three or more times a week, whereas those with eczema or other serious dry skin conditions should consider exfoliating only once only per week. For more information, check out the ViaBuff posts about exfoliating dry skin and exfoliating oily skin.

Support from Merryweather Foam
People who are looking to exfoliate their skin are bombarded with an endless variety of exfoliating tools – dry brushes, loofahs, mesh puffs, nylon puffs, exfoliating creams – the list can go on and on. Exfoliators like loofahs and nylon puffs harbor exceptionally high amounts of bacteria. Dry brushing and some exfoliating creams can create small tears in the skin. That’s why Merryweather Foam worked with the ViaBuff design team to help create a custom series of ViaBuff Exfoliating Puffs. These puffs not only last 30% longer than most other exfoliating tools, but also to protect against bacteria colonization. Our customer service team at Merryweather worked intensely to source the right foam that would be ideal for the Viabuff skincare exfoliation products. "We settled on an open cell polyurethane foam because it's known for its durability and ability to customize its properties," describes Ryan McCune, Vice President of Customer Service. "We started by sampling different types and colors of the urethane foams to the ViaBuff design team to gather feedback from customer trials. We don't want to be known as just a foam fabricator. Instead, we want to be known as a team of experts that learn the needs of our customers and help find the best solution for their application," says McCune. Ultimately, the ViaBuff team decided on four different exfoliation intensities and colors of open cell polyurethane foam.


The ViaBuff is the first to offer a thorough yet gentle exfoliation, and custom designations for different skin types and concerns, as outlined below.

 B2ap3 Thumbnail ViaBuff Exfoliation Types

* Level 1 - (Purple) is great for those oily skin, acne-prone skin or sensitive skin;
* Level 2 - (Green) for normal to eczematous skin types;
* Level 3 - (Pink) for ingrown hairs, freshly waxed skin and keratosis pilaris;
* Level 4 - (White)forexceptionally dry skin.


ViaBuff Puffs also are available for those with combination skin, such combining Level 2 and 3, 3 and 4, and 1 and 4, etc. ViaBuff handles are also sold so that those with mobility issues or have trouble exfoliating hard-to-reach places can have an easy exfoliating experience.


Why Exfoliating Puffs?
"We chose to make an exfoliating puffs as opposed to exfoliating mitts and pumices because these puffs provide a stronger soap lather and are more durable for all-over body use. In 2014, we launched the product so that people with varied skin concerns and types could finally have an exceptional total body exfoliating experience," says ViaBuff Representative, Jim Inama. Made from an open-cell polyurethane foam, the ViaBuff puffs were formulated specifically promote speedy air-drying, which in turn reduce the likelihood of bacterial growth on the puffs. With over 1,200sq/in of usable surface area, ViaBuff Exfoliating Puffs offer a more efficient exfoliating experience than most store-bought puffs and loofahs. ViaBuff Puffs’ cell structure enables them to absorb a small amount of water so that more exfoliating product stays on the surface of the puff, thus ensuring a more thorough and deeply-penetrating exfoliation.


Where Can I Purchase ViaBuff Products?
ViaBuff products can be purchased at ViaBuff.com and Amazon. If you are interested in selling ViaBuff products or would like more information, feel free to contact This email address is being protected from spambots. You need JavaScript enabled to view it. or visit their customer support page.
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