We see mold on outdoor cushions, Persian rugs, commodity tufted area rugs, on indoor furniture that has been in storage, as well as on carpeting that has been over-wet during a cleaning or flooded. We see our fair share of it so it only makes sense that we are always up to speed on our mold knowledge and education.

An outdoor sofa with an excessive amount of mold growth.

Molds are very common in both residential and commercial spaces. Mold thrives in places with a lot of moisture – leaky roofs, windows and pipes and residue from flooding are all places where it will start. It grows the best on wood products (paper, cardboard, ceiling tiles, wallpaper) as well as in or on fabrics (upholstery, drapes, carpeting, rugs, dust, insulation and even drywall. In our industry particularly cellulosic fibers such as cotton, linen, and rayon are particularly vulnerable, but proteins such as wool and silk can also be affected. Mold will even grow on synthetic fibers such as nylon and polyester if they are soiled or if they have finishes that provide food for the organism.

When we think about fabrics, we know that natural fibers are hydroscopic (they absorb water or moisture very quickly, and dry slowly.) This is why we are very careful about how much water we use and that we have control over drying conditions.

Microscopic mold spores are always around us. They can enter your home or office through the air, or attached to clothing or pets and walked right in. When they land on one of their favorite damp spots like I mentioned above, they will grow. Generally, stagnant air above 80% humidity will support mold on cellulosics—cotton or linen. Above 92%, on wool and silk. Synthetic fabrics like polyester or nylon do not absorb much moisture. Soiling, organic residues, and stains from handling textiles will all enhance the growth of mildew on fabrics at lower humidities, as will certain finishes on leather or wood. Humid air that is cooled but not dehumidified will have a very high relative humidity. Many building materials provide suitable nutrients that encourage mold to grow.

Ever wonder about that musty, mildewy smell? This is caused by volatile components of the fungi/bacteria (mold.)

The first thing that comes to mind when people thing about mold is BLACK MOLD!! The danger of Black Mold is highly exaggerated.

Molds generally fall under one of three categories- Allergenic, Pathogenic or Toxigenic. Toxigenic molds can produce toxins (specifically “mycotoxins”). Hazards presented by molds that may produce mycotoxins should be considered the same as other common molds which can grow in your house. Not all fungi produce mycotoxins and even those that do will not do so under all surface or environmental conditions. There are very few reports that toxigenic molds found inside homes can cause unique or rare health conditions such as pulmonary hemorrhage or memory loss. These case reports are rare, and a causal link between the presence of the toxigenic mold and these conditions has not been proven.

Mold growth can be many different colors and can smell musty.  Color is not an indication of how dangerous a mold may be.  Any mold should be removed and the moisture source that helped it grow should be removed.

The three most common types of indoor molds are Allergenic (not terribly dangerous or harmful to you) and are listed below:

Aspergillus (most species are Allergenic)


Where it is commonly found

Health Complications

Can be gray, greenish, or dark in color

Soil, grains, seeds, decaying vegetation, houseplants

Crawl spaces, walls, ceilings, subfloor, etc.

Mild allergic reactions

Minor health complications

Lung disease and more serious reactions for immunocompromised individuals

Cladosporium (Allergenic)


Where it is commonly found

Health Complications

Green, yellow, or black spots

Cooling units, damp building materials, carpets, insulation, curtains, decaying plants

Most species are not harmful but can lead to allergic reactions or worsen asthma

Rare infections in the eye, ear, sinus, or skin

Penicillium (Allergenic)


Where it is commonly found

Health Complications

Fluffy Blue or Green in color

Organic materials (paper and wooden materials, textiles, etc.)

Soil, decaying plants, grains, rotting fruit- Stale bread, nuts, and fruits

Allergic reactions

Triggers asthma

Sinus infections

Black mold is a toxigenic mold, but again – all molds should be treated the same way – prevented if possible and removed if not!

When faced with a moldy situation, most people just want to get rid of it – to scrub it off. People frequently give us their fabrics so that we can remove the mold.

Unfortunately, mold growth can cause staining, weakening, or complete destruction of fibers. Molds feed by digesting the substrate on which they grow, so the evidence they leave behind is alarmingly vivid. You would think that some cleaning would improve the dark spots left behind by mold, but it doesn’t. And the harder you scrub the more you damage the fiber, which is already compromised from the mold. So it’s a losing battle.

Our industry is pretty closely tied to the remediation industry, which is where we generally refer a lot of mold concerns. We do step in, however, when it comes to cleaning moldy and musty fiber and fabrics. Our approach to mold is to treat the area with an anti-microbial disinfectant that is safe for upholstery. This will kill the spores – then we give the fabric as aggressive of a scrub as the fiber can handle before it is further compromised. Meaning, if we scrub too hard, the fabric will rip because it is weakened. The problem is that although the fabric or rug will be clean and bacteria free, it may not look so much better after the cleaning.

Cushions Treated for Mold before and after cleaning

Below are 5 Tips on Preventing Mold.

  1. Fix sources of any water problems or leaks to prevent mold growth.
  2. Reduce indoor humidity (to 30-60%)
    • Venti bathrooms, dryers and other moisture-generating sources to the outside
    • Use air conditioners and de-humidifiers
    • Increase ventilation and air circulation
    • Engage exhaust fans whenever cooking, dishwashing and cleaning
  3. Clean and dry any damp or wet building materials and furnishings within 24-48 hours to prevent mold growth.
  4. Prevent condensation: Reduce the potential for condensation on cold surfaces by adding insulation.
  5. Do not install carpeting in areas where there is a moisture problem.

I you didn’t prevent and you’ve discovered mold, a health risk may be present. The type of mold growing in your home is not so important, regardless of what type you have, you should be remove it and the CDC does not recommend or perform routine sampling for molds. Since the effect of mold on people can vary greatly, either because of the amount or type of mold, you cannot rely on sampling and culturing to know your health risk.

Six Steps to Treat a Mold Problem:

  1. Mold growing in homes and buildings means that there is a moisture issue. This is the first problem to address.
  2. Remove moldy items from living areas.  Once mold starts to grow in carpeting or rugs, insulation, ceiling tiles, drywall and other materials, the only way to deal with the problem is by removal and replacement.
  3. It is important to properly clean and dry the area as you can still have an allergic reaction to parts of the dead mold – mold will regrow if there is still a source of moisture.
  4. Remove or replace carpets and upholstery that have been soaked and cannot be dried promptly. A professional cleaner can help to sanitize and treat for mold.
  5. Clean up and dry out your home thoroughly and quickly (within 24-48 hours) after any flooding.  Dig out and remove mud and dirt.  Scrub cleanable surfaces (such as wood, tile, stone) with soapy water and a bristle brush. Thoroughly clean all hard surfaces (such as flooring, molding, wood and metal furniture, countertops, and sinks) with water and dish detergent. Dry surfaces quickly and thoroughly. If you have a fan, air conditioner or dehumidifier use it to help surfaces dry after you finish cleaning.
  6. Mold growth can be removed from hard surfaces with commercial products, soap and water, or a bleach solution of no more than 1 cup (8 ounces) of bleach in 1 gallon of water to kill mold on surfaces. Never mix bleach with ammonia or other household cleaners.

In summary – Mold is not our friend (leave it to the scientists to squeeze the good out of it) and water and moisture is what encourages it to land and grow. Mold can aggravate anyone with even mild allergies and sensitivities, so keep the moisture levels down in your home, don’t allow water to leak or stand or build up. If you see mold – eradicate it and bring your area rugs upholstered pieces to Mother Nature’s Cleaning in San Rafael for proper treatment and decontamination.