Photograph: mold hidden behind basement wall paneling Use Light to Find Mold & Surface Contaminants

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How to use a flashlight or other light to spot building contaminants on surfaces.

If you don't know exactly how to aim your flashlight you won't see important, possibly toxic, light-colored molds. In this mold testing article we tell you how to use your light effectively look for hard-to-spot mold growth.This document describes how to make proper use of the level of light and direction of light to find mold and test for mold in buildings.

This mold detection procedure helps identify the presence of or locate the probable sources of mold reservoirs in buildings, and helps decide which of these need more invasive, exhaustive inspection and testing. The fact that mold is "hidden" or hard to spot on some surfaces in buildings does not mean you cannot find it.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

USING LIGHT - How to use proper lighting to see mold contamination in buildings

Aiming light properly shows the light-colored mold next to the black moldLight colored mold next to obvious black mold

Aiming a bright flashlight along this wall surface where dark mold was obvious shows a light gray/green fungal colony which in fact was far more toxic and thus important to select as an additional source for surface sampling using adhesive tape.

How and where you shine light is of crucial importance when looking for mold in buildings.

Light-colored mold such as some members of the Aspergillus sp. and Penicillium sp. groups are often the dominant problem-mold in buildings but these offenders are often missed by a casual inspection because they can be hard to see on surfaces.

You need a bright flashlight and as simple as this seems, you need to know how to use it.

Shine the flashlight along the surface being examined, not straight at the surface. If you shine the light directly at the surface being inspected you may not see a thing. As you'll see in the mold photographs shown here, using your light carefully can make a big difference in what mold you find and where you find it.

We inspect for any mold growing on building surfaces. White, gray, light green, red, yellow, or other colored-molds may be allergenic or toxic. Looking only for "black mold" touted in the popular press risks missing the most important mold in a building.

Some black molds such as the Ceratocystis/Ophistoma group are simply cosmetic. Other toxic black molds such as Stachybotrys chartarum are rarely airborne unless mechanically disturbed such as by demolition.

Aiming light properly shows the light-colored mold on this panelingThese "toxic black molds", especially if the genera/species are heavy, sticky, not-normally-airborne mold spores (Stachybotrys chartarum is an example) may actually affect building occupants less than highly-airborne but small, light-colored, hard to see mold spores such as members of the Aspergillus sp. family.

Finally, finding any mold growing on building surfaces is an indicator of mold-friendly conditions and means, in turn, that other non-black but still highly-toxic or allergenic problem mold genera/species might be present. So it's usually reasonable to interpret any mold we see in a building as evidence of mold-conducive conditions which may, in turn, justify further investigation.

Light colored toxic mold on paneling can be hard to see in ordinary lighting and requires careful inspection. But notice how the lighting shows that this paneling is buckled. I'd suspect that it has been exposed to high moisture if not water, and that there is risk of hidden mold on the cavity side of this material.

This is a case in which the careful use of light shows not mold but rather undulations in the wall paneling surface which in turn means moisture and mold risk.

Further inspection was needed - an inspection of the hidden side of paneling, drywall, and the wall cavity. We did not actually find mold inside this wall - which goes to show that where there's moisture there is not always a mold problem. But the evidence merited looking for mold.

direct lighting hides problematic light colored mold colony on this wainscot paneling

Light colored toxic mold on paneling is not visible because light is being shone directly onto the wainscot wood paneling surface.

The angle of reflected light back to the inspector's eye makes it difficult to see small particles on the surface even though the light is very bright.

Now try shining a light along the surface - this easily shows the white mold colony.

The angle of illumination along the sides of small particles shows their presence more easily than in the direct-illumination example just above.

direct lighting hides problematic light colored mold colony on this wainscot panelingWhen we work in the forensic laboratory with a microscope, we use both transmitted and angular reflected light to examine small particles as different information is provided by each method.

The point of these illustrations of using light to help look for mold in buildings is to demonstrate that "hidden mold", like the purloined letter, may in fact be hiding in plain view - you just don't know how to see it.

Recent news articles have made some people terrified at the mere mention of "toxic black mold" such as "Stachybotrys chartarum." Actually it is common to find Stachybotrys chartarum in small amounts in houses where there has been prolonged leakage or water entry. It's a toxic mold that should be removed.

But don't assume that anything and everything black on a building wall is a highly toxic mold.Some black stuff is not mold at all. Other common mold species look black but may be of low or no toxicity. For example, Chaetomium globosum™has been reported to be allergenic rather than toxic. Cladosporium sphaerospermum is often found growing indoors on bathroom tile or refrigerator gaskets. It's a member of the most common mold family, Cladosporium, the "universal fungus." It can look pretty "black" on some surfaces.

Can you tell what genera or species a mold is that's growing on a surface just by the naked eye? No. Though I've inspected and tested so many molds on so many surfaces that like a bird watcher, I know what's likely to be present in a given habitat. (Refrigerator gasket mold is usually a Cladosporium, often C. sphaerospermum and mold growing on window muntins will be a genera/species tolerant of UV light. A normal person can't do this.

You cannot determine the mold genera and species just by looking at it on the wall, and please skip those do-it-yourself mold test kits. The methods the kits use are fundamentally inaccurate and in a few cases so are their laboratories. For small mold problems, spend your money on some soap and water instead.

For larger mold contamination problems (more than 30 square feet) you should hire an expert to survey your home, or send your own mold sample to a competent testing laboratory. The services of an experienced mycologist or aerobiologist are necessary to know what you've got. ©DJF Copyright protection trap. ©Daniel Friedman


Continue reading at LIGHT, GUIDE to FORENSIC USE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see HIDDEN MOLD, HOW TO FIND - mold you won't see without more invasive methods

Or see LIGHT AIM FINDS MOLD - how to aim your light to spot hard-to-see mold contamination on building surfaces & materials

Or see UV LIGHT BLACK LIGHT USES for use of a black light for mold and other forensic applications in builidings.

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LIGHT, FLASHLIGHT for MOLD at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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