Can Mold be Cleaned from Materials?

can mold be cleaned

When visible mold is discovered in a property on materials or surfaces, a common question is, ‘can mold be cleaned?’  They may also wonder if they should clean the mold themselves.

Cleaning mold depends primarily on two things:

  • What you are attempting to clean;
  • How heavily the mold has impacted the material or surface. Note: If mold is extensive enough, it may require a mold professional to inspect and/or perform remediation.

Mold on materials or surfaces are primarily differentiated by whether they can support the mold growth directly, that is, whether mold can feed on the material.

Examples of materials that are not themselves a food source for mold (non-nutritive):

  • Glass
  • Metals
  • Most plastics (for common molds, at least)
  • Most urethane and other synthetic wood finishes
  • Synthetic fibers
  • Concrete
  • Stone
  • Ceramic materials
  • Other inorganic materials

Examples of materials that do provide a food source for mold (nutritive):

  • Leather
  • Most traditional wood finishes (shellac, lacquer, varnishes), which are organic in origin
  • Wood
  • Paper
  • Natural fibers (cotton, linen, wool, etc.)
  • Drywall (paper surface)
  • Many paint films
  • Most organic materials

Can Mold be Cleaned off ‘Non-nutritive’ Materials?

mold on bathroom tileWhen items are not a food source for mold, the mold growth on the surface will be feeding on a dust film.  When dust film is cleaned thoroughly from the item, the mold goes right with it.

Clearly, the less porous or irregular the surface, the more easily the dust or dirt is removed. Many non-nutritive surfaces and materials can be quite difficult to clean.  For instance, synthetic fiber upholstery can become coated with soils such as human body oils and skin flakes, an excellent food source for mold, and it can be difficult to remove these soils thoroughly enough to also remove all the mold.  The same applies with irregular surfaces such as concrete and porous ceramics.

A good example of mold on a surface is a tiled shower.  Mold is usually growing in a film created by soap, minerals, body oils and skin flakes. Most tiles are relatively non-porous surfaces. Thereby, removing the mold growth becomes much easier. Removing mold from the grout, which is much more porous and irregular, is a lot more challenging.

What about Cleaning Mold off ‘Nutritive’ Materials?

 

For these materials, mold can feed not only on dust/dirt present on the material, but also on the material itself.  A chair upholstered with a cotton fabric, for example, can support mold growth on human oils and skin flakes, as with the synthetic upholstery.  But the mold can also feed directly on the cotton fibers, digesting and damaging them directly.

 

Can Mold be Cleaned Safely?

Many materials, both nutritive and non-nutritive, can be very challenging to clean because the processes necessary to remove the mold will inherently damage the material.  For instance, heavy mold growth on drywall is basically not cleanable, because aggressive mold cleaning will damage the paper surface, making the drywall no longer usable.  On the other hand, most unfinished wood surfaces can be cleaned because aggressive “cleaning” methods such as sanding or media-blasting can “resurface” the material, removing the damaged outer layer and exposing a “clean” new surface.

Even when materials or surfaces have had all mold removed, they may have been damaged or discolored by the mold growth. As a result, this discoloration/damage may remain, often giving the impression mold is still present when it is not.

At times, the question ‘can mold be cleaned?’ would best be determined by a mold remediation expert. For example, the expert can predict what results can be anticipated as well as the best methods to use to remove mold and discoloration without damaging the material. For further information on mold removal procedures, see the IICRC-S520 standard for professional mold remediation.

If in need of an mold inspection or remediation protocol, contact IET today.

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About the Author

Timothy D. Toburen, CR, CMR, AMRT, is an environmental consultant with IET and has over 35 years experience in restoration services, with expertise in water and fire damage restoration and mold contamination issues. He is highly qualified to estimate and supervise restoration and mitigation projects and teach others to do the same. Download CV

2 comments

  1. T says:

    Very surprised to see you cite “most unfinished wood surfaces can be cleaned….”! Mold hyphae are known to penetrate very deeply into wet wood & other “nutritive” materials. Furthermore, it is the toxic materials contained in mold structures & cells that are primary threats to human health. What research studies can you cite that prove that there are no residual hyphae &/or mold toxins in wood that has been “cleaned”? Based on my reading of tech literature, I am skeptical of your general assertion that wood can be “cleaned”.

    • IET says:

      Thanks for your response. My claim is based on the consensus of published industry standards such as IICRC S520 Standard for Professional Mold Remediation. http://www.iicrc.org/standards/iicrc-s520/

      The “cleaning” referenced in the article for unfinished wood surfaces is not surface cleaning such as vacuuming or damp/wet cleaning processes. It instead refers to what we call “aggressive cleaning,” methods that actually remove the top layers of wood, in which the hyphae and toxins you mention are embedded. This might be more appropriately referred to as “resurfacing,” and often results in a surface that visually appears brand new. The article was not intended to be an exhaustive discussion of cleaning methods.

      Effective methods of aggressive cleaning include sanding or wire brushing while HEPA vacuuming and blasting methods using a variety of media such as soda, dry ice and walnut shells. The idea is to physically remove the top, damaged layer of wood. This may be 100 to 300 microns thick, is the thickness of 1 to 3 sheets of paper, which is quite a distance on the scale of mold biology. In addition, it is often appropriate to encapsulate or seal the aggressively cleaned or resurfaced mold to seal in any residual mold particles.

      This assumes the wood is basically sound. The types of mold we are speaking about here are often referred to as “surface molds,” because they do not penetrate deep below the surface. They can begin to grow on wood when its moisture content reaches roughly 17%. The types of rot-decay fungi that can penetrate deeply into wood require a much higher moisture content and extensive time to break down and penetrate deeply into the wood substrate.

      Sincerely,

      Tim Toburen
      Environmental Consultant

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