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Comparing Packaging Materials

Posted on: December 10th, 2014 by travis

With so many options when it comes to your packaging materials, it’s good to have a basic knowledge of the properties and characteristics of each material before making a final choice for your product.  At Cooler Warehouse, we have the ability to create a custom package to fit your specific requirements.

Expanded Polystyrene (EPS)

Commonly referred to as Styrofoam, EPS foam is extremely lightweight and easy to mold and cut.  It is resistant to moisture and provides moderate shock absorption.  It’s highly effective insulation capabilities make it ideal for insulated shipping containers and box liners.  It is also the most economical of the expanded plastics, providing excellent thermal protection at a relatively low cost, and reducing shipping costs by reducing the total weight of the shipment.  For these reasons, we use EPS foam for our insulated shipping boxes and EPS box liners.

Expanded Polypropylene (EPP)

Expanded polypropylene is similar in appearance to EPS, but with greater shape memory.  Since EPP will maintain its structure and deform without breaking, it is excellent at absorbing shock and is commonly recommended for very fragile or high-cost items.  While it is a higher cost material, these costs can often be justified by significantly reducing the number of items damaged in transit, translating to an overall cost savings.

Expanded Polyethylene (EPE)

EPE has many of the same properties as expanded polypropylene, including its energy absorption capabilities and its shape memory, but it is even more elastic than expanded polypropylene.  It generally has a softer feel and and is highly resilient, with good shear strength.  This is also a higher cost material than EPS.

To discuss your product, packaging needs, and potential shipping solutions, please give us a call at 717-227-6036 or email us at

R and K-Values: Evaluating your Insulated Shipper

Posted on: November 25th, 2014 by travis

When trying to determine the effectiveness of an insulated shipping container, there are a few properties that will tell you a lot about the package’s performance.  The most basic of these measures is known as the “K-value”, or the measure of thermal conductivity of a material.  This is measured in Watts per meter-Kelvin (W/(m·K)).  Since thermal conductivity refers to the amount of heat being transferred, it follows that a high-quality insulated shipping container should have as low a K-value as possible.

The most commonly used measurement in insulation calculations is the “R-value”.  The R-value measures the thermal resistance of a material, or group of materials, and is measured in (m²·K)/W.  It is proportional to the thickness of the material.  Since thermal resistance is also inversely proportional to thermal conductivity, a higher R-value is desirable for an insulated shipping box.  This means that the material, expanded polystyrene in this case, has a higher resistance to the transfer of heat from outside temperatures to the product inside.

The most comprehensive measure of a a system’s insulation capabilities is the U-factor, also known as the “Overall Heat Transfer Coeffeicient”, and it relates to both the R and K-values.  The U-factor is equal to (1 / R-value), which is also equal to (K-value / thickness of the material).  Similar to the K-value, a low U-factor is indicative of a high level of insulation.

So what are these values for our insulated shipping boxes?  Our EPS foam coolers have a density of 1.2 pounds per cubic foot, and are a standard 1.5″ (.0381 m) thick.  EPS of this density generally has an R-value of about 3.9 (m²·K)/W per inch of thickness.  This gives our insulated shippers an R-Value of about 5.85 (m²·K)/W.  This translates to a standard K-value of about .26 W/(m·K) per inch and an overall U-factor of of only .171 W/(m²·K)!  By limiting the transfer of heat with a K-Lock™ Insulated Shipping Box, your products remain safe from the fluctuating temperatures and breaks in the cold chain.


EPS and the Environment

Posted on: November 17th, 2014 by travis

Recent decades have made it clear that the concern for our global environment is on the rise.  In an effort to reduce our carbon footprint and preserve the delicate balance of our ecosystems, there is an ever increasing demand for responsible and efficient use of our resources.  With this goal in mind, let’s take a look at at the impacts that Expanded Polystyrene has on our lives and our environment.

EPS is safe, non-toxic, and chemically inactive.

There are no health risks associated with expanded polystyrene at any stage of it’s production, intended use, or in the the waste stage of it’s life cycle.  Since EPS has no nutritional value of any kind, it makes it extremely difficult for mold or fungus to grow.  This makes it ideal not only as insulated shipping boxes for food and medicine transportation (even direct contact is completely safe), but also for home insulation.  Since EPS is not water-soluble and is completely inert, it is not capable of causing any sort of water contamination.  When it comes to direct health concerns facing the people involved directly in the manufacturing, production, storage, use, and disposal of our insulated shipping containers and foam coolers, there are none.

EPS does NOT contain CFC’s or HCFC’s.

Clorofluorocarbons (CFC’s) and Hydrochlorofluorocarbons (HCFC’s) have been demonstrated to cause significant harm to the Earth’s protective Ozone layer, and have been increasingly regulated since the 1970’s.  At no point in the production, use, recycling or disposal process does expanded polystyrene contain or give off ANY CFC’s or HCFC’s.

EPS and “Greenhouse Gasses”

As with any product made from raw materials, EPS does have some impact on the environment.  Like all plastics, EPS is made from crude oil, a non-renewable resource that releases carbon dioxide into the environment.  However, between fuel, heating, energy, etc., EPS uses only about 0.1% of the oil used by mankind every year.  This minimal consumption, however, results in large environmental benefits as well.  According to an 1986 APME study, houses and buildings that use EPS as an insulator will save 70 lbs of oil for heating and energy for every 1 pound of oil used to create the EPS.  More relevant to our insulated shipping boxes, are the savings achieved through transportation.  Because expanded polystyrene is 98% air and extremely light-weight, using it as a packaging material will ultimately result in a significant reduction in fuel consumption when compared to other packaging materials.  EPS is a perfect example of using our resources responsibly and efficiently.

Waste Management

There are several options for when an EPS insulated shipping container or other packaging material comes to the end of it’s life.  The first is to recycle the material.  EPS is 100% recyclable and we encourage all of our customers to recycle their insulated packaging materials.  Another alternative is known as energy recovery, and is made possible by EPS’s high calorific value.  By clean burning the used EPS at very high temperatures, combustion energy is created that can then be used for heat and electricity.  This process is generally emits fewer pollutants than an average campfire, while recycling energy and keeping the EPS out of the landfills.  When recycling and energy recovery are not possible, the landfill is the last resort.  The good news in this case is that EPS accounts for only about 0.1% of total municipal waste, and it’s chemical properties make it perfectly safe and unable to cause any sort of soil or ground water contamination.

As you can see, the environmental positives of using EPS for home insulating and insulated shipping boxes outweigh the minimal environmental impact.  As with any resource, it is always important to reduce, reuse, and recycle.  For more information about the relationship between expanded polystyrene and our environment, check out the following sources:

1. Foam Fabricators Inc. – EPS and the Environment

2. – Environment

3. – EPS and the Environment


About ISTA 7E and Standard 20

Posted on: November 10th, 2014 by travis

In October of 2010, the International Safe Transit Association published the ISTA 7E Testing Standard for Thermal Transport Packaging, to be used in conjunction with the ISTA Standard 20.  Increasing regulatory measures have generated a need for a comprehensive qualification standard for shippers of temperature-sensitive products; a problem that ISTA addresses with these guidelines.  By itself, the ISTA 7E is useful for general qualification and testing of insulated packaging materials when no official certification is necessary.  By obtaining and using the Standard 20 in addition to the ISTA 7E profile, shippers are able to obtain the ISTA 7E Certification for their packages.


The ISTA 7E is a set of standard temperature profiles, developed as the aggregate of many real-world shipping observations.  As temperature data loggers have become smaller and more wide-spread, they have given us a better glimpse into the actual temperature variations that an insulated shipping container will encounter over the course it’s transit.  It was found that extreme highs and lows were actually very uncommon, and that any temperature reading below 0°C or above 35°C was not only extremely rare, but also very short lived.  The ISTA was able to use this new knowledge to create risk-based temperature profiles that would use temperatures that a package could expect to encounter a vast majority of the time, rather than a worst-case scenario approach.

The Standard 20

In order to obtain ISTA 7E Certification, The Standard 20 guidelines must be purchased and used alongside the 7E profile.  The Standard 20 has three main guidelines.

  1. Training:  At a minimum, a Certified Thermal Professional Level I and a Certified Thermal Professional Level II must be active in performing and reporting the tests.
  2. Lab Protocol:  Documenting, data packages, and test reporting must all be done in the specified formats outlined in detail in the Standard 20.
  3. Lab Audit: An audit on the onsite testing laboratory must be completed by a Certified ISTA Thermal Transport Lab Auditor.

To learn more about the ISTA 7E, the Standard 20, and ISTA 7E Certification click here or visit



Choosing the Right Size Insulated Shipping Box

Posted on: November 3rd, 2014 by travis

It is important to select the right size insulated shipping box for your frozen and refrigerated products.  A box that is too small may not be able to contain both your product and the amount of refrigerant you will need to keep your product in the required temperature range.  Choose a size that’s too big and you may find your product thawing quicker due to empty space inside the container, increased damage from a lack of structural support, and unnecessarily high shipping costs.  Here we have provided you with a quick and easy guide to selecting the K-Lock™ Insulated Shipping Box that is right for you!

1.  Arranging the Pack-out

Arrange your products on a flat surface as you intend to pack them inside the cooler.  It is important to minimize the size of the shipping container by keeping your arrangement as compact as possible.

2.  Plan ahead for Gel Packs or Dry Ice

If you plan on using a refrigerant with your shipment, be sure to allow space for these at this stage of the process.  We recommend using gel packs on as many sides of the product as possible, but at a minimum allow room for the gels to be placed on top of the product.  The dimensions of K-Lock™ Gel Packs are as follows:

 6 oz:  4″ x 4″ x .75″          8 oz:  6″ x 4″ x .75″          12 oz:  6″ x 6″ x 1″          16 oz:  6.25″ x 6″ x 1″

 24 oz:  8″ x 6″ x 1.5″        32 oz:  8″ x 8″ x 1.5″       48 oz:  10.5″ x 8″ x 1.5″

3.  Add “Finger-Room”

Remember to add just enough space to make it easy for your customer or end user to be able to reach in and remove the product with ease when it has arrived at it’s destination.

4.  Select your Insulated Shipping Box

Go to our catalog of K-Lock™ Insulated Shipping Boxes and find the shipper with the smallest possible shipping box that will accommodate the dimensions of your final pack-out.  Be sure to select a model number ending with A (for assembled) if you want your cooler to come inside a corrugated shipping carton.  If you only need the foam cooler, select a model number ending in FO (for foam only).  Before shipping, remember to fill in as much extra space inside the shipper as possible.  You can use newspaper, extra refrigerant, packing peanuts, or some other form of dunnage to maximize the shipments insulation capabilities.

Panel Lined Shippers: A Cost-effective Solution

Posted on: October 27th, 2014 by travis

There are a variety of reasons that a customer may not be willing to invest in molded foam coolers for their temperature sensitive shipments.  Some may have odd-shaped products, or need the ability to incorporate several different products into one size package.  Others may have products that are too large for standard sizes of molded foam.  Whatever the reason may be, we at Cooler Warehouse want to help!  We offer custom sized coolers that do not require custom molds or tooling.  These EPS panel lined shippers consist of an outer shipping carton and six customized foam panels made from the same high quality EPS foam as our K-Lock™ Insulated Shipping Boxes.  We can assemble the coolers for you on-site, or send you everything you need to do it yourself!  Simply use packaging tape to form your outer box, insert the bottom piece of foam, four sides, your product, and any gel packs that you require.  Then add the top piece of foam and tape up your shipment!  Taping the package securely keeps the six foam sides fitting tightly together, and will ensure high quality insulation over the course of transit.  Most EPS panel lined coolers are designed with what we call “wrap-around” sides, which follow each other around the outside of the box as shown here.  If you would like to use the same box for multiple products of varying sizes, we can design the foam sides so that one or more can be adjusted inside the same outer shipping carton.  This ensures that your larger items have the space they need, and your smaller items get the insulation and protection they require!  Contact Us today to learn more about our EPS panel shippers and molded foam coolers.

How are Molded Foam Coolers Made?

Posted on: October 23rd, 2014 by travis

One of the most important characteristics of Expanded Polystyrene, or EPS, is it’s ability to be molded into custom shapes.  Raw material, referred to as “expandable polystyrene beads” have to be pre-expanded in order to prep them for molding.  The expandable polystyrene contains a small amount of pentane, and when heated by steam, this pentane causes the beads to expand to many times their original size.  This material is then allowed to cool and age until it becomes a stable bead, ready to be molded into a foam cooler.  These beads are then injected into an aluminum mold, which allows steam to enter through small vents and reheat the beads.  This causes the beads to expand once again and fuse into a single shape, which the EPS retains even after cooling.  The process is known as thermoforming, and the result is a lightweight, durable, and well-insulated shipping container.

Dry Ice vs. Gel Packs

Posted on: October 17th, 2014 by travis

When trying to determine what refrigerant your product will require, the most important factor to consider is your desired temperature range.  While dry ice and gel packs for shipping both have they’re strengths and weaknesses, the main difference comes in their temperature.  Gel packs, like K-Lock™ Synthetic Gel Packs, are water based.  This means that they freeze and thaw at roughly the same temperature as water would, around 0°C (32°F).  Dry ice is much colder, maintaining a temperature of around -78.5°C (-109.3°F) as it sublimates and becomes CO2 gas.  If your product needs to arrive in a hard freeze, and there is no lower temperature boundary, then dry ice may be a good option for you.  Many products, like some medications, cannot be kept at the extremely cold temperatures of dry ice.  Other products simply do not require this much refrigeration.  For products like these, gel packs for shipping are a great alternative.  They do not get to the extremely cold temperatures that dry ice does, and will actually last longer, generally keeping the pack out between 2° and 8°C depending on the weight and starting temperature of the product.  If you are unsure if gel packs are right for you and your business, contact Cooler Warehouse for more information!

Shipping with K-Lock™

Posted on: October 14th, 2014 by travis

If you are new to cold-chain logistics, then there are certain things that are important to know before you begin sending your temperature-controlled products out into the world.  Maybe you have started an online business, and want to send frozen or perishable food items to your customers.  Maybe you are sending important biological samples or pharmaceuticals.

Whatever your application, here are a few tips to help you get started.

Scheduling you Shipment

Whenever possible, plan to send your shipment early in the week.  This will give them the best chance to arrive at their destination before the weekend and avoid sitting for a couple days.  Make sure you allow about 24 hours for your gel packs to freeze.  (Full pallets of gel packs can take much longer, sometimes several weeks to freeze all the way through.)

Packaging your Product

It is best to protect your product by making sure there is some sort of plastic barrier between the product and the refrigerant.  Cold packs for shipping will often condensate;  a plastic bag or container will make sure your product stays nice and dry.

Creating the Pack-out

Since K-Lock™ insulated shipping containers from Cooler Warehouse come already assembled inside an outer shipping box, all you need to do is remove the cooler lid and you’re ready to start packing.  For the best results, try to surround as many sides of your product as possible with frozen gel packs.  At the very least, place the cold packs on top of your product.  The amount of frozen gel packs required may vary depending on the weight and nature of your product.  If you aren’t sure how much you need, give us a call!  We can test your product inside our environmental chamber and tell you exactly how much refrigerant you need to last as long as you need.

Fill in the Void Space

Fill in as much of the empty space in your pack-out as possible using newspaper, bubble-wrap, or some soft material you may have handy.  This will help to further insulate the container and reduce the amount of heat that can escape.

Ready to Ship

Secure the lid of your K-Lock™ molded foam cooler and tape up the shipping carton.  Slap on a shipping label and you’re ready to ship!

What is Expanded Polystyrene?

Posted on: August 26th, 2014 by travis

Expanded polystyrene is a plastic material that you may often hear referred to as Styrofoam.  While this is not entirely accurate (Styrofoam was actually a trademark of the Dow Chemical Company),  many of the products you think of when you hear Styrofoam are in fact made from expanded polystyrene, or EPS.  All of the coolers and insulated shippers available at Cooler Warehouse are made from this material.  The structure of EPS foam makes it the ideal material for a variety of manufacturing applications.  It is made up of thousands of tiny beads of low-density polystyrene, which makes it both durable and lightweight; a perfect combination for shipping!  Since the cells of the tiny beads are not interconnected, heat has a hard time travelling through expanded polystyrene, making it high-performance insulator.  This combination of qualities make EPS Foam, and K-Lock™ Molded Shipping Boxes in particular, an ideal cold-chain shipping solution.