Cheeki makes a single wall and a double wall vacuum insulated drinks bottle. Both are BPA free and toxin free and are made from food grade stainless steel. How does a double wall insulation keep your drink cold for 24 hours and hot for 12 hours?
Firstly, we don’t use any plastics, foams or other materials to insulate, only air. Vacuum in this context means a "space with no matter." So, how it works is relatively simple yet extremely effective. Our insulated bottles have two layers of stainless steel, an inner wall and an outer wall with a thin layer of air between the two layers. This keeps the inside temperature different to the outside temperature.
To explain it further, stainless steel is good at transferring both cold and hot temperatures. For example, if you put 4-degree water in a single-wall bottle the temperature would transfer to the stainless steel very quickly making the bottle around 4 degrees. If the outside air is 24 degrees (room temperature) there will be a 20-degree difference and the bottle will start to equalise to the outside temperature.
Now, the double wall insulation simply prevents the transfer of hot and cold temperatures. When you pour your 4-degree water into the insulated bottle the inner wall will quickly match the water temperature. The outer layer will stay a room temperature and when you touch it you won’t notice that it’s has cold water in it. This is due to the layer of air between the layers that acts like a buffer. It prevents the cooler layer touching the warmer layer thus preventing the transfer of temperatures. Even if you put cold water in a black insulated bottle and left it in the sun the bottle on the outside may become too hot to touch but the inside will still stay cold.
Another great feature of our insulated bottles is that they will not become wet from condensation. Condensation occurs when humid air comes into contact with a cold surface and forms water droplets. With the outer layer never becoming cold it wont "sweat" keeping your work desk, dinner table and bag dry.
A little tip, this can have a negative when putting your bottle in the fridge to cool your water as it won’t unless you open the lid.
It’s simple, effective and safe. So, if you want to grab a bottle that keeps your drinks hot and cold for long periods of time go the insulated. If you prefer a light bottle then go the single-wall.