I Pulled Out Shoes I Hadn’t Worn All Winter… and Found White Fuzzy Patches Growing on the Leather. What Is This?

Even if shoes appear dry, humidity trapped in storage can provide enough water for mold growth.

2. Warm Temperatures

Mold thrives in mild to warm environments.

Closets, garages, and storage spaces often create ideal conditions.

3. Poor Airflow

Air circulation helps remove moisture.

Without it, humidity accumulates.

4. Organic Material

Leather itself provides nutrients.

Natural oils and residues become food sources for fungal colonies.

The Smell Test

One of the easiest ways to identify mold is by smell.

Ask yourself:

Do the shoes smell musty?

Do they remind you of:

  • A damp basement
  • Old books
  • Wet cardboard
  • A humid attic

If the answer is yes, mold is highly likely.

Mold often produces a distinctive earthy odor that remains even after surface cleaning.

Could It Be Something Other Than Mold?

Surprisingly, yes.

Not every white substance on leather is mold.