Can Mildew Turn Into Mold?

We’ve all been there, something smells musty and you follow your nose to investigate. Nine times out of ten, your nose takes you toward damp, dark places like under a sink, crawlspace or wet basement wall. Maybe it’s even your washing machine or damp storage room that’s filled with cardboard boxes. Wherever you are, you’ve discovered what you’re pretty sure is mildew and you wonder..Can Mildew Turn Into Mold? If so, when?

The quick answer is: Yes, mildew can turn into mold. If fact mildew is a mold and it would love nothing more for you to leave it alone so it can do it’s thing and turn into a full blown fungus.

To prevent this from happening, you’ll definitely want to know: What are mold and mildew? Are they the same thing? What health problems are caused by mildew and mold? How do you remove mold or mildew from your home? So let’s dive a little bit deeper…

What is the difference between mold and mildew?

Mold and mildew are often grouped together when you hear them. You hear statements like there’s “mold in the kitchen” but “mildew on the bathroom wall.” Are they the same thing?

In brief, mildew is a mold, mold is a fungi and so mildew (being a mold) is also a fungi….as young as fungi gets. The spores are carried on air and grow on wet organic materials. Set a cardboard box (organic) in a damp basement and soon enough you’ll begin to see white-grey spores arrive. And if you’ve ever taken off for vacation with wet clothes in the washer (cotton is organic), you’ve probably returned to stinky (mildew smelling) surprise that takes a wash or two to remedy.

The Differences

Mildew grows on a surface and is a typical pre-cursor to what we can visually observe as being mold. Once matured, mold fungi begins rotting the surface and burrows inside the organic material it is feeding on.

Mildew typically is gray or white, and powder-like, appearing in circular shapes. Sometimes, especially on boxes, mildew is mistaken for dust or debris. Mold on the other hand is noticeably mold. It has colors of black, brown, or green and even orange purple and yellow. It will be irregular, fuzzy, and/or slimy.

What Causes Mildew?

It’s a good thing we can’t “see” air because it’s filled with spores. Most spores in the air will simply die because they never get to land on anything suitable for breeding. However, when organic materials like wood, cardboard and cloth get wet and stay wet, they become perfect homes for the lucky spores that happened to land atop.

The key to avoiding mildew formations is dry, fresh air. This is why bathrooms have vent fans to help evaporate the water from surfaces more quickly…it’s not for human comfort. Leaving a vent fan on for a few minutes after you have finished your shower will reduce the chances of mildew growing. If you don’t have a vent fan, open a window, or leave the door open so that air can circulate.

How Does Mildew Affect You?

Mildew can cause or aggravate many respiratory conditions such as asthma, COPD, sinus infections, and more. Vulnerable people like infants and the elderly should avoid areas where mildew has been found.

Being microscopic, mildew is an airborne organism easily breathed in through the nose or mouth. It causes problems because it collects on the tiny air sacs in the lungs and in mucus membranes, clogging them, preventing the body from processing sufficient air.

The most common reflex to dislodge the spores is coughing or sneezing. If left in the lungs too long, infection will set in and chronic breathing illnesses can develop. Even if you are healthy, while cleaning mildew wear a filtering mask and limit the time you are exposed.

Signs you have been exposed to mold or mildew

Symptoms can vary in severity but these are common reactions to mold or mildew exposure:

  • wheezing, asthma attacks, etc
  • congestion of the nose or sinuses, dry, hacking cough
  • burning, watery, redness in the eyes
  • sneezing fits, bloody noses
  • rashes or hives on the skin
  • headaches, memory loss, mood changes

How To Remove Mildew Stains

Mildew is only a surface contaminant, though it will gather in creases, like corners and tile grout. A 10 percent bleach solution does kill most mildew spores. Mildew can leave behind a black stain. If it is not removed, mildew can quickly return.

Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is a boron compound, a mineral, and the salt form of boric acid. Powdered borax is white, consisting of soft colorless crystals that dissolve in water. Made into a paste, borax will clean even stubborn stains quickly.

Why Does Mildew Smell

Mildew produces a musty, damp smell. The smell is often compared to “sweaty socks.” The smell is a side effect of the mildew’s consuming the wet, organic materials. Mold smells are much stronger.

Plain white vinegar can eliminate the musty smell associated with both mold and mildew. A cup of vinegar added to washes of musty-smelling clothes works great. 

When Does Mildew Become Mold?

If mildew has been allowed to exist on a surface too long, it will eventually mature into colonies of mold spores.

Mold is the mature form of fungus. Mold spores clump into “colonies”  No longer just on the surface, mold eats into the wet material (drywall, wood beams, etc). This process causes the heavy, rotting smell associated with the presence of mold.

The different types of mold fungus are distinguished by their color. Different mold spores grow on different types of organic materials and in different conditions. Mold can be black, brown, white, or green.

How Does Mold Affect You?

Mold creates more severe respiratory conditions for people than mildew. A mild cough might become a “hacking cough.” A “bit of trouble” breathing may become the inability to breath at all. Lung tissue will likely be damaged.

Many people with mold infections must be treated with prescription medications to regain their health.

Removing Mold

While most mildew problems can be solved with home remedies like bleach and borax, mold requires stronger methods. The mold is often burrowed into the walls and under surfaces so it is cannot just be wiped away as this is the equivalent of a haircut.

There are some over the counter mold cleaners. The active ingredient will kill most mold, but some mold infestations (like black mold) will require professional cleaning. Also, physical damage may need to be repaired because of the mold rot.

Mildew vs Mold on clothes

Clothes are made of organic materials and therefore can gather both mildew and mold if not properly dried. As previously mentioned, if you’ve ever left a load too long in the washing machine before transferring it to the dryer and the clothes smelled musty, this is because they picked up mildew.

Clothing abandoned in hurricane-damaged homes will often be moldy by the time the homeowner has been allowed to return to the flooded property.

Cleaning Mildew or Mold From Clothes

To remove mildew from clothes, dissolve one-half cup of Borax in two cups of hot water added to a laundry load.

To remove mold from clothing, add a cup of plain white vinegar to a bucket of warm water. Soak clothes for about an hour. Wash clothes with standard laundry detergent in hot water.

How to Prevent Mold and Mildew

The best defense against mold and mildew and the illnesses they can cause is keeping surfaces clean and dry. Here are some tips:

  1. Keep humidity levels low indoors – use air conditioning.
  2. Fresh air – open windows on a low-humidity day will keep circulate away mold and mildew spores and evaporate moisture.
  3. Dry wet surfaces thoroughly as soon as possible. Large water puddles on bathroom floor do not evaporate quickly enough to prevent mildew.
  4. Keep indoor plants – succulents in particular (potted or hanging ferns, ivy, cacti, etc.). These absorb water from the air.

Resources and further learning

Centers for Disease Control, U.S. Federal Government

“Mold and Mildew in Your Flood Damaged Home,” Federal Emergency Management Agency

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