When Humidity Takes Over: Mold, Mildew & What You Can Do

This summer in Washington, D.C., the humidity has been relentless — with levels hovering above 80% for weeks. One of my clients discovered firsthand what that kind of moisture can do in a space with zero air circulation. A simple backyard storage shed, packed with treasured items, turned into a perfect incubator for mold and mildew.

Everything natural was affected: wooden furniture, paper goods, leather, books, and even vintage picture frames. Mold thrives in dark, damp, unventilated spaces, and it doesn’t discriminate. Once it takes hold, it can spread quickly and quietly, often before you even know it’s there.

Cleaning Mold from Wood and Other Natural Materials

If you find yourself in a similar situation, don’t panic — but do act quickly. Here’s how I tackle mold and mildew on wood and other organic materials:

1. Safety first:
Wear gloves and a mask. Mold spores can cause respiratory issues, especially if disturbed.

2. Remove items from the space:
Take everything outside if possible. Sunlight and fresh air are your friends here.

3. Dry out the space and contents:
Use fans or dehumidifiers to remove moisture. Nothing should be cleaned until it’s completely dry.

4. Clean affected surfaces:
For wood, I use Murphy's Oil Soap to gently clean the surface — it’s effective and doesn’t strip natural oils. For a deeper clean and protection, I follow up with Oil Conditioner/Wood Oil to restore moisture and create a barrier against future damage.

5. For paper goods and books:
Use a soft brush or cloth to gently remove mold spores. If they’re valuable or sentimental, consult a paper conservator — mold can be extremely difficult to fully remove without damaging the material.

Restoring Mold-Damaged Leather

Leather goods — like purses, belts, and jackets — are especially vulnerable to mold in humid environments. Here's how to bring them back:

1. Wipe down surface mold:
Mix equal parts white vinegar and water. Use a soft cloth to wipe the leather gently. Do not oversaturate.

2. Use a leather cleaner:
Once the surface mold is gone and the item has dried, use a leather cleaner specifically formulated to remove dirt and residue without harming the finish. I like Lexol or Chamberlain’s Leather Milk for this step.

3. Condition the leather:
Leather loses its natural oils during cleaning, especially if vinegar is used. Apply a leather conditioner to restore suppleness and prevent cracking. Buff gently with a soft cloth after applying.

4. Air out thoroughly:
Allow leather items to dry completely in a well-ventilated area away from direct sunlight before storing again.

Prevention Moving Forward

• Add air circulation: vents, fans, or propping the door open periodically can make a huge difference.

• Use moisture absorbers or a small dehumidifier in enclosed spaces.

• Keep organic materials elevated and off the ground, away from condensation and pests.

• Consider storing leather and paper goods inside sealed plastic bins with silica packs if the shed must be used long term.

High humidity is a reality in many regions, and our belongings — especially natural ones — need help to survive it. With vigilance, the right tools, and some care, you can fight back against mold and mildew and protect what matters most.