A nice fresh coffee is the preferred option, but some people use a vacuum flask to get their coffee fix on the run. Another option is to use a vacuum flask to carry your hot water for later use.
The vacuum flask can keep your liquids warm, hot, or cold for long periods of time. The near-vacuum inside provides insulation.
The design uses two flasks, one within the other which are sealed with a lid. The interesting part is what materials are used in their construction. Common materials are glass lined, stainless steel, aluminium, ceramic and plastic. Materials used in the lid can make a difference, eg silicon.
- Taste
- Glass lined is least likely to alter taste.
- Stainless steel can change the flavor a little bit.
- There are many types of plastic, but they can impart an unpleasant taste.
- Silicon and plastic lids may impart an unpleasant taste
- Durability (will it break?)
- Stainless steel is tough and can last a long time. It just dents ;).
- Aluminium is pretty tough.
- Plastic can be brittle and depending on the quality, may not last long.
- Ceramic is also easy to break if you are not careful.
- Glass is notorious for breaking.
- Weight
- Plastic and aluminium are likely to be the winners here.
- Cleaning
- Glass is least likely to have an issue being cleaned.
- Plastic can have some issues with abrasion.
- Safety
- Plastic can be toxic! If you are using plastic, please make sure it is safe (especially if it is an old flask). Look for a BPA free vacuum flask.
- Cost
- Plastic is likely to be the cheapest
Check out a selection of vacuum flasks here.
Vacuum Flask History
Thermos is actually a brand name that has become a generic term.
The inventor of the vacuum flask was Scottish scientist Sir James Dewar. He created the vacuum flask in 1892 for use in his scientific research, but never patented it.
In 1904 two German glassblowers realized the vacuum flask could be used to keep drinks cold or warm. They used the trademark Thermos for their product.