Leather shoes mould if they are damp when they are put away, or if stored in a humid area. The mouldy leather feels hard, and discolouration makes the shoes appear ruined, sometimes referred to as "green shoe syndrome." However, careful cleaning with denatured alcohol and water will save your shoes and leave them in almost new condition. The key is waiting a few minutes for the cleaner to soak into the leather surface so the mould spores will wipe away easily.
Pour the alcohol and water into the spray bottle, and tighten the spray nozzle. Gently shake the bottle to combine the alcohol and water.
Spray the alcohol and water mixture over the mouldy leather surface, until the surface is visibly wet. Allow the mixture to soak in for 3 minutes, then wipe the cleaner and mould off of the shoes with a soft cloth, using a small, circular motion. If any mould spots remain, spray another coat of cleaner on the shoes and wipe dry after another 3 minutes.
Allow the shoes to dry completely. Dip a soft cloth into the wax shoe polish, and apply using a small, circular motion and firm pressure.
Buff the shoes, using the shoe brush and a wider, circular motion.