How to Clean a Flask With Leather 
A flask can develop an unpleasant smell after prolonged use, but it can be easily removed. All you need to do is mix vinegar with water. Vinegar is an excellent natural deodorizer. This cleaning solution will ensure that your flask stays fresh for a long time.
Bicarbonate of soda
Bicarbonate of soda, or baking soda, is a great cleaning agent for a flask. You can use it to remove stains and clean it without using soap. However, if you want to keep the flask’s sleek and shiny appearance, you should never use soap on it.
The downside of using baking soda to clean a flask with a leather surface is that it can be messy. You should try using the substance on a small, inconspicuous part of the leather first. You also don’t want to get too much baking soda on the leather surface or it will clump up.
To clean a flask with leather, you can use a solution of bicarbonate of soda and water. Mix a solution of the soda with water until it reaches the base of the flask. Pour the mixture into the flask and allow it to soak for at least 10 minutes before you pour it out.
White vinegar
If you want to clean a flask made from leather, here are some helpful tips: Never wash it under the faucet. Instead, use a mild cleanser mixed with water and scrub the flask with a cloth towel. Be sure to use the right cloth towel as paper towels tend to ruin the leather. After cleaning, apply a waterproofing spray or rubbing lotion to make the leather water-resistant. A popular brand is Nikwax.
White vinegar can also be used to clean patent or soft suede. White vinegar contains less than five percent acetic acid, making it a safe choice for leather. You can also use a brush to smooth out the suede after cleaning. If you don’t have a brush, use a second dry cloth to wipe the leather.
You can also use hydrogen peroxide in place of vinegar. This solution is particularly useful when cleaning food thermoses, as it will kill bacteria. However, make sure to rinse the flask thoroughly after use and make sure that there are no traces of hydrogen peroxide.
Uncooked rice
When cleaning a flask, you should use uncooked rice to remove residue that can be hard to get to. This grain is small enough to scrub the flask but not so abrasive that it can damage the flask. You can use it to clean both the outer and inner sides of the flask.
It is important to rinse the flask thoroughly after cleaning it with the rice solution. This can be done by using a soft sponge or a dishrag. You can also use dish soap if you need to clean tough areas. However, natural methods are the best, and the rice is a good alternative.
Rice is also a great way to remove burnt bits. A mixture of vinegar and water will also dissolve any remaining food particles. Alternatively, you can make a paste with baking soda and water and wipe the flask with the solution.
