PORON Cushioning Blog Blog

PORON Cushioning Blog

Comfort and High Fashion…Yes they CAN Live Together! Insole Choices for Your Favorite High Heels

Posted by Nicole Perry on Thursday, February 9th, 2012 | 2 Comments »

I’ll be the first to admit…I LOVE SHOES!!  But I’m certainly not alone.  With the start of New York’s Fashion Week just upon us, many girls and guys alike will be searching the internet, scanning magazines and watching TV for the latest styles and trends.

But it never fails, each year there are also those models who unfortunately fall victim to the wonderful, yet strange looking footwear of which they can barely (if at all!!) make it down the runway.  I’m a believer that fashion is also an art form…but there are some art pieces that need to stay in the galleries rather than taken home for every day use.

Runway aside, there are those of us who will spend the night padding our nicely pedicured feet with unsightly bandages or making up for our “Girls Night” by wearing unsightly slippers the rest of the week because our aching feet can’t take anything else.

I call those bandaged days my “Pre-PORON® Cushioning Days” and although I’ll describe a few other cushioning materials used in high heels, I’ll warn you… this blog post may be a bit more biased than my previous posts.  There certainly are applications where other cushioning materials may be good substitues for PORON Cushioning.  We’ll be the first to recommend them if the design and function require so.  But for continuous comfort and shock absorption in your favorite high heels…my mind is made up!  But to make it fair, I’ll give my material reviews and ask that you send me your comments and reviews on other materials you’ve found!

Cushioning Materials in High Heel Shoes

Regardless of shoe design, cushioning for high heel shoes typically consist of one, or a combination of the following materials:

–   Polyurethane foams (such as PORON® Cushioning)

–   Latex

–   Neoprene sponge

–   EVA

–   Gel

To keep it simple, we’ll break down our rating to:

–   Shock absorption (measured by peak G impact testing)

–   Durability or the resistance to break down after multiple uses (measured by Compression Set Testing, more information on C-Set can be found here)

–   Breathable (air permeability testing)

–   Thin and Lightweight (measured in millimeters and density…remember we don’t want to sacrifice style!!)

–   Even pressure distribution (pressure mapping)

–   Antimicrobial

 

So how do the competitive materials stack up?

 

Shock Absorption and Repeated Use

I’ve combined these because high heel shoes undergo more pressure than your standard footwear.  When you wear heels, the area you are walking on is much smaller than if you were wearing running shoes.  For example, I’m sure we’ve all heard the comparisons where a woman in high heels exerts more pressure on the point of her shoe than an elephant standing on one foot.  If you want to calculate it out, pressure (p) is the force per unit area applied in a direction perpendicular to the surface of an object.  (Thats p = F/A)  Or visit this article from Jack Green  who works it out nicely for us.  Either way, its certainly true!  Even though many argue that the pressure is only for a micro-second, those micro-seconds add up and exert a tremendous amount of strain on the body.

Therefore, you not only need a material that offers the best shock absorption, but also one that continues to offer the best shock absorption use after use.  I certainly want to wear my $150 stilettos more than once!!

To measure continuous shock absorption, we can look at two tests:

1.   The first is repeated Peak Deceleration (g’s) impact testing, where the lower the “g’s” the better a material is at absorbing impact.  You can see from the chart, that even after repeated impacts, the PORON Cushioning continues to offer the lowest Peak G rating.                                

2.    Next, Compression Set (C-Set) Resistance as measured by ASTM D3574 Test D.  Here the foam is compressed 50% at 158°F (70°C) for a 24 hour period.  Afterwards the thickness of the foam is measured to determine how much the foam “took a set” or basically broke down from being under continuous pressure.  (As a side note: I can’t image the temperature in my shoe reaching 158°F, but better safe than sorry!) 

From the graph below, you can see PORON Cushioning easily maintains its thickness and performace even after being subjected to 24 hours of  high temperatures and pressure.

 

 Breathable

Air permeability is relatively easy to measure.  I’ve even seen home tests where water is placed over a material and air blown threw the foam…thus causing air bubbles on the other side for breathable foams and no bubble for non-breathable foams.

We can also take a look at SEM photos to see the cell structures of materials.  The following picture compares PORON Cushioning (an open cell, breathable foam) versus EVA (a closed cell, non-breathable foam).  This graphic also shows what happens to closed celled foams when they are compressed.  (This adds more data to our C-Set discussion above.)  Mainly the pressure causes the air inside the closed cells to burst through the cell walls and theys can not recover back to their original state.  More info on open cell vs. closed cell can be found on a previous post on the PORON blog.

 PORON Cushioning materials are open cell, therefore air is pushed out when they are compressed and air is refilled when the material is not compressed.   I like to use the image of tiny foam springs below your feet.  As you walk, the PORON Material compresses and flexes, allowing air to freely pass through the material.  This also helps to keep your feet feeling cool and comfortable!

But you may be wondering about gel inserts?  Gels must be encased in order to maintain their shape, thus they are not a breathable material and often become sticky and leave behind unwanted residues as a result.

 

 

Thin and Lightweight

I started this post out with the heading “Comfort and High Fashion”!  You want a material in your shoe that you can benefit the most from minimal thickness and weight.

PORON Cushioning materials are available to designers in a variety of thicknesses (1.0mm to 16.0mm), densities and formulations.  Therefore designers have the ability to choose the right PORON Material for their unique design needs.

In the shock absorbency tests described above, a thinner PORON Cushioning material can be used to replace a thicker latex, neoprene sponge, EVA or gel insert.  Furthermore, besides EVA’s (which remember lose their thickness and performance over time) PORON Cushioning materials are typically lighter weight than the competitors.  For example, when comparing a gel pod with the same sized PORON Cushioning pod, gels are heavier and denser.

 

 

 

PORON® Performance Cushioning Pod

 

Comparable

Gel Pod

 

Comments

 Weight, grams

0.8839

2.657

 Gel pods are 3x’s heavier
 Density, lb/ft

17.05

52.38

 3x’s denser

 

Even Pressure Distribution

Pressure mapping certainly brings a great graphic to the discussion.  Below shows a standard insole made from EVA foams when compared to a PORON Cushioning insole.  You can see the yellow and red areas that appear from the high pressure areas.  Furthermore, since PORON Cushioning maintains their shape, size and fit, you’ve just reduced your chances for calluses and blisters!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Antimicrobial

We are talking about footwear!  No one wants bacteria build up or smelly footwear while walking to dinner with friends.

Many foams can be treated with antimicrobial agents but often the treatments can wash off and wear away.  PORON Cushioning is infused with Microban® Antimicrobial Technology from the beginning stages of manufacturing…thus you can be assured it’ll stay with you even during those late night dance outings!

 

 

 

Okay…so for the final overview!

 

In Stores Now!!

I’ll send out my “Thank You’s” to two brands who not only use PORON Cushioning in their products, but have also allowed me to maintain my love affair with fashionable shoes!

1)  Foot Petals – Ladies, find them on-line and pass them around to your friends.  The shoes you’ve thrown in the back of your closet, never to be seen again, still have a chance!  I’ve had to hide my samples from some Rogers employees because they are always in high demand!

 

 

2)  Kenneth Cole with 935 Technology – I’ll let you see the videos for yourself.  These shoes have been put to the test and the results…YES, you can buy 3” heels and walk a mile + in them!

 

Okay, so for the disbelievers, here is your chance.  If you’ve found a material which works for you…send me samples!  I’d love to check them out.

– Cheers to a Comfortable night on the town 😉

Nicole Perry

Nicole Perry

Global Market Segment Manager for PORON Comfort materials. Nicole has been involved in the Footwear industry for over 15 years. She also has over 25 years working with high performance materials including custom injection molded and cast polymers for automotive, apparel, electronics, equipment and medical markets. Nicole is passionate about bringing great technologies to market and working with companies that share the goal of helping people enjoy life no matter what they are doing. She holds an MBA from Nichols College.

2 Comments

  • Dear Ms Walters,
    Thank you for the informative article about Poron for high heels. I read is with great interest both as a woman who loves to wear heels, and as an inventor who discovered that Poron was the perfect choice of material for my high heels shoe insert prototypes. In fact I tried out the entire list of materials that you wrote about as cushioning material for use inside shoes before I came across a Poron heel cushion that I cut up for my prototype. I have recently invented (patent pending 2013) a new style of high heel shoe inserts made of Poron that make high heel shoes wearable for three to five hours comfortably, can be fitted by the customer to their own unique foot shape with a template, and stop the foot from sliding forward and sideways at two points; these being in front of the ball of the foot and in front of the heel. The two inserts work in tandem to stop the foot from sliding off the heel area, and the toes from sliding forwards and crushing into the toe box of closed shoes or into ‘toes overhang’ in high heel sandals. Further the entire foot is completely stabilized as it is held firmly in place by being blocked in between two points. My foot is so stable that I can run in high heel sandals when I have my inserts inside them. The inserts are completely hidden under the foot as they are quite small -but mighty – therefore making them suitable for wear in any style of high heel shoe or boot, including thin strapped high heels sandals. I hope you will be delighted to know that there is an invention out there that makes high heel shoes more comfortable to wear than they have ever been before. You may hear more from me, as I have been working with a manufacturer in Quebec, who has recently requested assistance from Rogers company for the manufacture of my unique and new design for high heel shoe inserts.
    Hope to read more comments in your column soon.
    Sincerely
    Virve Georgeson
    (inventor of Killer Heels Comfort high heel shoe inserts)
    P.S. The website Killerheelscomfort.com will be up by Jan. 2015

    • Hello Virve,
      Thank you for your comments and feedback! I hope that your development is moving along well. Please let us know if we can be of further support, and do keep me informed as you get ready to launch the website!
      Thank you
      Angela

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