When you store shoes or boots, most often it is not enough to simply wash them and dry them, but also disinfect them. This is crucial for any shoes that you plan on wearing long-term to prevent nasty smells and more importantly, the spread of harmful microorganisms

Often, the common shoes we know and wear are produced from cheap materials. Simply put, if your shoes are very old and worn out, you should probably change them for hygienic and health reasons. High quality, well made shoes can last a very long time, but it is important we periodically disinfect ALL shoes that we plan to wear on the daily.

Instructions and things we need:- Around 20 to 25 percent solution of Formalin OR vinegar- Around 40 percent acetic acid solution- A piece of cotton cloth or similar- A cellophane bag or similar

Method 1:Remove the insole from your shoes, remove your shoe laces, and any type of fasteners from them.Wet the pad of cotton inside acetic acid or the formalin solution. Carefully rinse the bottom part of the inside of your shoe, paying attention to the joints and seams.
Inside the shoes carefully insert two pieces of cotton wool soaked with in formalin or vinegar. Now we are ready to pack the shoes and insole and seal them tight in the bag. Leave them for 24 hours. After 24 hours remove take the shoes out of your bag, they are disinfected! Leave them to ventilate out in the open to remove the smell of the chemicals.
You should pay more careful attention to where your toes are places in the shoe, as that is the area most prone and in risk to bacterial infections and other nasty things. If you can remove the inner soles of the shoe, do it and soak it in the solution.
Vinegar or Formalin, which should I use to disinfect my shoes at home? There are pros and cons to both, of course, but you should use whatever is more practical to you.

Method 2:
The biggest con perhaps with vinegar is that 40% pure vinegar is hard to find, and making your own concentration can be a hassle, however vinegar is advisable as it is a bacterial killer. Using this solution to disinfect your shoes will yield incredible results, as it is sufficient to simply soak a piece of cotton with vinegar, put it in your shoe, and seal it tight for 24 hours, however you may encounter difficulties trying to ventilate and get rid of the strong smell afterwards.
Formalin on the other hand does not smell any nicer, but it is easier to get the solution right and is again, very effective in disinfecting and killing the unwanted bacteria, fungus and so on. When using formalin make sure to moisten the cotton well and rub the entire inner part of the shoe gently, again, paying attention to joints and seams, with ventilation and drying, this I found to be a bit easier to to get rid of the smell than the vinegar. Formalin is considered a bit easier on artificial leather and rubber, so have that in mind.
In conclusion, try out the solutions and just work with whatever is best for your and your shoes’ needs.