Hydro Flasks are extremely popular water bottles that can keep ice for 24+ hours and can keep drinks hot for 12+ hours. But what is a Hydro Flask made of and how do they manage to work so well?
Hydro Flasks are made from high-quality food grade 18/8 stainless steel. The inside has no liner and the outside is powder coated with paint that is a thermoset polymer. There is a vacuum between the inner and outer wall of the Hydro Flask that is sealed using a proprietary method.
Hydro Flask bottles are incredible inventions and it's amazing how long they can keep drinks cold and hot for. What's even more interesting is how they achieve this while making the bottles out of very simple materials.
What Material Are Hydro Flasks Made From?
Hydro Flasks are made from high quality food grade 18/8 stainless steel, which is one of the most commonly used forms of stainless steel.
The 18/8 refers to the percentage of chromium and nickel in the stainless steel. The chromium works to make the material corrosion resistant and the nickel adds strength to the material making it less likely to warp, chip, crack or break.
This material is common in both personal and commercial kitchenware and is food safe and corrosion resistant.
The inside of a Hydro Flask bottle doesn't have any lining. There is no plastic film or any other substance on the inside of the bottle. This means your water or drink is coming in direct contact with the stainless steel. Don't worry as this is considered safe – read my article on if Hydro Flasks cause cancer.
Hydro Flasks are made from an inner and outer wall with a vacuum in between, which is what does the insulating. Both the inner and outer walls are made from stainless steel that is bent into shape to create the bottle.
What Plastic Is Used To Make Hydro Flask Lids?
Unfortunately there is no information online about exactly what type of plastic Hydro Flask lids are made from, however they do state that all their plastic lids are BPA free.
I own both a standard Flex Cap lid and a wide Straw lid and neither have indicators of what plastic they use.
The Flex cap lid seems to use multiple types of plastic. The inside of the lid is hard and shiny and smooth to touch while the outside top of the lid has a more rubbery texture and the U-shaped finger handle is quite flexible.
I have resorted to asking Hydro Flask directly through their website what type of plastic exactly is used in the lid but I am currently waiting on a response from the company.
What Paint Is Used on Hydro Flasks?
One of the main stand out features of Hydro Flask bottles is their unique and bright color designs.
The outside of Hydro Flask bottles are painted using a process called powder coating. The paint is applied electrostatically and then it is cured under heat.
This type of paint is much stronger and less likely to scratch off then regular using wet paint and it also gives a more uniform finish and doesn't show streaks or drips. Click here to learn what to do if you do get a paint chip on your Hydro Flask.
There are a few different ways to powder coat products and there are different materials used to do it. It is unclear exactly which type of paint Hydro Flask uses but you can learn more about powder coating at Wikipedia. This article also outside many of the key ingredients used in powder coating if you wish to explore it further.
What Material Do Hydro Flasks Use To Insulate Their Bottles?
Hydro Flask bottles are great insulators, but what is Hydro Flask insulation made of and why does it work so well?
Hydro Flask insulation is made from absolutely nothing, literally. The reason Hydro Flasks are so good at insulating is that they use a vacuum to stop heat entering or exiting the bottle.
Hydro Flask bottles are made from an inner and outer wall of stainless steel and in between these two walls they take out all the air and create a near-perfect vacuum.
Most heat needs particles to move through so by removing all the particles from the space and creating a vacuum most heat can't pass through.
This stops outside heat getting into the bottle and making your ice melt and it also stops heat escaping the bottle when it's filled with a hot drink.
So the secret to how Hydro Flasks insulate so well and what insulation they use is….nothing!
What Materials Are Used To Create The Vacuum Seal in Hydro Flasks?
Vacuum seal technology is not new. It was actually invented way back in 1892!
Hydro Flask simply took this technology which was previously only used to keep food like soup hot and applied it to water bottles and keeping drinks cold.
However, the manufacturing process used to create the vacuum seal in most bottles leaves a trace amount of lead on the bottle, which can be very harmful to humans.
In 2013 and 2014 Hydro Flask worked hard to remove the use of lead from their manufacturing process. I talk more about this in the story behind Hydro Flask.
They created a proprietary sealant they call TempShield, but there is no information online about what ingredients are used to create this seal.
Get a Hydro Flask
Hydro Flask are great bottles. While they are expensive they are the only brand I know that use TempShield and don't use lead in their manufacturing process.
They also have a lifetime warranty, a fun brand and some amazing colors.