Design Explained –
Our Steam Vent Caps

Do you know that most of our rice cookers have a cap on the steam vent? Compared to conventional rice cookers, our advanced rice cookers – the ones that utilize a microcomputer – are sleeker, with tight-fitting components and lids. We make these rice cookers with steam venting systems that consists of three components – a vent, a vent cap, and a vent cap receptacle.

This is the Steam Vent Cap!

Each piece of the venting system has a purpose. The vent is a tube-like opening that goes through the cover and inner lid, into the body of the rice cooker where the inner pan rests. The vent is covered by the steam vent cap, which rests in the steam vent cap receptacle, keeping it securely on the cover of the rice cooker. The entire system is built to seamlessly blend into the top of the rice cookers. One customer even brought his appliance into our office inquiring about the system because he didn’t realize it was there!

Can you spot the Steam Vent Cap?

The steam venting system works in conjunction with good rice prep. The first step is to correctly measure the right amount of rice and water. Then, it’s important to wash the rice correctly, removing excess starch and bran or dust from the rice kernels. Once the rice begins cooking, the rice cooker releases excess steam through the vent, and the steam vent cap catches any foamy substances that come out with the steam. The rice cooks better this way because the steam vent cap allows the rice cooker to cook your rice at a higher heat, without worrying about overflow because the steam vent cap can capture excess moisture and bubbles that may foam up.

Yay for delicious rice!

As long as the vent cap is washed under running water and the steam vent cap receptacle area is wiped with a soft cloth to remove any moisture, the steam venting system in your Zojirushi advanced rice cooker should work wonderfully. Remember to remove and clean the inner lid and you’ll have perfectly cooked rice every time!

Don’t forget to remove and clean the Inner Lid!

Check out our full line up in the Products section, and be sure to comment with any questions you might have.


Design Explained – Our Superior Vacuum Insulation

Zojirushi has been in the vacuum insulation business for over 100 years! The company opened its doors in Osaka as the Ichikawa Brothers Trading Company in 1918 manufacturing vacuum liners, and began manufacturing vacuum bottles in 1948. We’ve been designing vacuum insulated products since then!

Vacuum insulation is a specific type of insulation that uses a man-made vacuum between two panels of materials, such as glass or stainless steel, so that the temperature of the fluids or gases on either side of the panels are isolated and don’t affect each other. The concept of a vacuum insulated flask was originally developed in the West in 1892 by James Dewar, a scientist who was interested in cryogenics and in developing supercooled substances like liquid hydrogen. Dewar needed a way to keep the liquid hydrogen cool, so that it wouldn’t evaporate, and came up with a vacuum insulated flask made of two walls of glass. Vacuum insulated glass containers were at the heart of Zojirushi’s technology, until 1981, when we created our TUFFBOY line and patented the process to make vacuum insulated stainless steel containers.

Vacuum insulation has many benefits, which we’ve incorporated into our bottles, mugs, food jars, and lunch jars since the first vacuum bottle. The first benefit is the superior insulation. Vacuum insulation prevents heat loss through conduction. Since the air which is a conductor  – is removed between the inner and outer layers of stainless steel, heat isn’t transferred. In fact, a gap as small as 1 mm for the air can insulate the food or drink inside your container!

If you remember from your school days, there are 2 other ways heat can transfer: radiation and convection. In a Zojirushi bottle, heat transfer is also prevented by insulating against radiant heat transfer. A thin sheet of aluminum or copper is wrapped around the outer surface of the inner layer to help reflect radiant heat.

And finally, heat transfer through convection is blocked by tightly sealing the lids on each of the products. For bottles, mugs, and food jars, the lid itself is equipped with a gasket to seal it onto the container, whereas lunch jars use a foam-insulated inner lid. Each of these three ways keeps food and beverages hot or cold for hours.

Along with managing heat transfer, using vacuum insulation makes all of our products lighter. Many thermal vessels use polystyrene foam or the addition of other materials to insulate, adding weight and bulk. Our vacuum insulation makes our products lighter and more compact.

Our superior vacuum insulation makes it easy to choose your favorite bottle, mug, food jar, or lunch jar. Pick between a non-stick coated or SlickSteel® interior. Choose the right size and capacity. And select your favorite color. Check out our full line up in the Products section, and be sure to comment with any questions you might have.

Design Explained – Mesh Safety Nets in Our Water Boilers

When designing our products, we choose our materials very carefully. We also consider how these materials are put together, with an eye towards functionality, practicality, ease of use, and maintenance. We’ve designed a mesh Safety Net into our water boilers, and this small component protects the dispensing mechanism in a smart way.

The Safety Net is a small, basket-shaped piece of metal mesh, fixed to the bottom of the inner containers of our water boilers upside-down. It prevents pieces of limescale or other debris from entering the dispensing mechanism, which pumps water so it can be dispensed. Limescale, which is generally comprised of calcium and other minerals naturally found in water, can build up inside the water boiler through normal use. Over time, limescale flakes off into small pieces that can get into the dispensing mechanism of the water boiler, preventing the machine from working properly. The machine makes a “grinding” sound when water is dispensed and eventually breaks. The mesh Safety Net acts as a filter that blocks rogue flakes of limescale from entering the water boilers’ dispensing mechanisms, and as a result, protects it.

Aside from making sure the filter is always in place when in use, we recommend treating your water boiler with our Citric Acid Cleaner once every three months. Doing so will remove limescale even before they flake off. Simply dissolve one packet of the Citric Acid Cleaner in a cup of warm water. Pour the mixture into your empty water boiler and fill the inner container with water. Close the lid and turn the machine onto the cleaning cycle, as per the instruction manual. Once the cycle finishes – usually about an hour later – unplug the machine and empty out the water. The final step is to rinse and dispense resulting in your water boiler becoming just like new! Check out our instructional video and if you ever lose your Safety Net, remember that a replacement can always be purchased from our Parts & Accessories store!

Stay tuned for next month’s Design Explained, where we talk about more smart and innovative features built into our products!

Design Explained – Our SlickSteel® Interiors and Nonstick Coatings

Which is better? Nonstick coated or not coated?

At Zojirushi, we know they’re both great!

This month we’re excited to share the design and engineering behind our nonstick and SlickSteel® bottle, mug, and food jar interiors. Both interiors are easy to clean. Both interiors have been proven durable. And both interiors are hygienic and repel stains. So why have two types of interior finishes?

Well, as usual, we believe in customer-centric design, and offer our products in both nonstick and SlickSteel® finishes to satisfy your requests.

As cleanability is important to our customers, many Zojirushi products are nonstick coated. Our nonstick coating is made using PTFE, or polytetrafluoroethylene, a polymer that is applied in a two-step process with a primer and a topcoat. It is nonreactive, inert, ultra-smooth, hydrophobic, and resistant to abrasions, corrosion, and heat. It’s ideal for use in containers that hold food or beverages, since it doesn’t stain or absorb odors. In Japan, our nonstick interior mugs are highly prized for their durability and cleanability, since they are primarily used for holding coffee and tea, which tend to leave odors and stains. Some of our newer bottles, such as the Stainless Mug SM-TA and Stainless Bottle SJ-JS, even utilize double-layer nonstick coating, to provide additional protection against salt-containing beverages such as sports drinks, as materials like salt will corrode stainless steel.

The SlickSteel® interior finish was introduced for our customers who prefer to avoid PTFE nonstick. We’ve electro-polished the interior, resulting in a surface that resists corrosion and repels stains without the use of nonstick coating. Electropolishing works using the principal of electrolysis, whereby the stainless steel is immersed in an ionized, electrolytic solution which is subjected to an electrical current. The reaction that results from the charged solution removes the microscopic peaks and fills the microscopic valleys in the stainless steel, creating an ultra-smooth surface made without any mechanical smoothing, grinding, or buffing.

Because eating out of Food Jars would require a utensil to be used, we use our SlickSteel® interior in all of them so that the nonstick coating is not scratched. Some of the other products with SlickSteel® interior are the Stainless Bottle SV-GWE50, our Stainless Mugs in models SM-JHE, SM-KHE, SM-SHE and our Travel Mug SM-YAE48. Both of our Stainless Tumblers in models SM-DA and SM-DD are SlickSteel® finished.

No matter what your preference is, both of our interior finishes showcase the same smart design and expert engineering you’ve come to expect from Zojirushi. Feel free to call our friendly customer service with any additional questions and of course, to help you select your next mug, bottle, or food jar!

Design Explained – Our Innovative Lids

Lids. Yes, we’re starting off 2019 talking about our lids.

Happy 2019, and we hope that you find this new series about how our smartly engineered product components work as interesting as we do! And lest you think we are a bunch of engineers sitting around geeking out about our products (which, we happily are!), we were inspired to write this series because of the many questions that you, our fans and enthusiasts, ask us.

One of the most frequently asked questions comes from those of you who use our bottles, lunch jars and food jars – the items that typically have screw-off lids. Upon first glance, many of our customers aren’t sure why our lids have multiple pieces, after all…isn’t one lid just like any other?

Of course not! We have designed our screw-off lids to cleverly solve a few problems, without requiring you to learn a new technology or to deal with lots of difficult processes. Let’s deconstruct the lid first.

It looks like a lot of pieces, but each one fits seamlessly and serves a purpose.

It looks like a lot of pieces, but each one fits seamlessly and serves a purpose. The Lid Cover and Lid Cover Gasket top the show. The Stopper Cover protects the inner stopper system, which is comprised of the Stopper, Valve Packing and Stopper Gasket, all of which help to prevent leaks. The Valve Packing helps manage pressure inside the main body that can be created when hot foods or drinks are stored in the container. The Lid Cover at the very top is removable to allow access to the Valve Packing when needed, and the extra space within the lid also creates an insulated barrier so that the temperature of the food or drink inside the main body is maintained.

Pressure release valve helps to release built-up pressure

The components of the inner stopper system are meant to seal the main body shut, and the Valve Packing manages the pressure inside of the container. Sometimes, when the containers are filled with hot foods or beverages, pressure can build up inside and seal the lid tightly onto the main body. This is great when you’re making Steel Cut Oatmeal To-Go in Your Food Jar, but not so great when you have to open that food jar! Rather than forcing the lid off, and potentially scalding yourself, we’ve designed the lid so that you simply take off the Lid Cover, insert a toothpick into one of the two small holes in the  Stopper, and release some of the pressure inside of the main body. This works the similar to the way pressure is released from a pressure cooker. Then, just screw the lid off and enjoy!

Removable mouth ring for drinking comfort

The Mouth Ring and Mouth Ring Gasket below the lid components are for drinking comfort, and the lid fits securely into this area. Additionally, the lid covers the area that touches your lips, keeping it clean. We’ve even heard that it’s great when your bottle rolls out of your bag onto the sandy beach, and the lid stays on to keep the drinking area clean of sand!

Most lids disassemble for thorough cleaning

Lids, because they come into contact with foods and beverages, can foster bacterial growth if they aren’t cleaned well and dried thoroughly. We’ve thought of that, too, and designed the lid to easily disassemble. Each component can be removed for thorough and hygienic cleaning.

Check out how convenient these smartly designed lids are – and of course, enjoy your fresh foods and beverages in our vacuum-insulated bottles, food jars and lunch jars. Our friendly Customer Service Representatives are available to answer any questions…especially the really geeky ones our product designers love!