For a deeper treatment consider using a sponge and only the tip of the cloth. [2] X Research source
If the paste does not thicken, add another spoonful of baking soda until you get your desired consistency. For lighter stains a paste may not be necessary. Adding 2 spoonfuls of baking soda to a small cup of warm water and applying with a clean rag, will do the trick. [7] X Research source
Letting the baking soda solution sit longer will not cause any damage to the fabric of your shoes and will ensure the removal of the entire stain. [10] X Research source
If the paste does not remove easily add a few drops of warm water to the cloth and wipe the area again.
These non-toxic cleaners will also protect your shoes from penetration from liquids. [13] X Research source They are also safe to use on leather and suede. [14] X Research source
Ethanol is low in toxicity and is used for many different things, including making a great solvent. [18] X Research source
The goal here is not to drown your shoe but to apply a small amount to get the stain out.
This may take a few attempts but the alcohol will ultimately attract the indigo dye out of your shoes.
