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This article explains how to find and test for light or hard-to-see mold growth on building surfaces. The photo at page top shows a hard-to-see light-colored (possibly toxic) mold on the surface of an interior door. It is easy to miss large areas of light colored mold like this unless a careful inspection is made and careful use of light is applied.

Too many "mold inspectors" are quick to test the obvious "black molds" found on building surfaces while they may fail to find and identify possibly more harmful mold species simply because they ignored the light-colored mold growth. This document describes how to find mold and test for mold in buildings, including how and where to collect mold samples using adhesive tape - an easy, inexpensive, low-tech but very effective mold testing method. See MOLD GROWTH on SURFACES for an index of what mold genera/species are frequently found on various building surfaces and materials.

This 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. © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Spotting light colored, hard to see, toxic molds indoors

Other mold species are light in color or nearly invisible when growing on an interior surface unless you look carefully. This desk sat in a wet basement for only two months yet it was rapidly covered with a toxic mold, Aspergillus niger. Aspergillus molds indoors can be difficult to see.

A. niger spores are tiny and are easily made airborne by the smallest disturbance. The basement housing this moldy chest had Aspergillus levels in air enormously higher than the outdoor sample.

Aspergillus on furniture

We find as much or more Penicillium/Aspergillus in houses than Stachybotrys, but these light green, gray or tan mold colonies are more difficult to see if you don't know how to look. To check more carefully and thus more successfully for mold, shine your flashlight along the wall surface in an area that has been damp or wet. Don't shine it right at the wall or you won't see much. Look where things have been wet or damp, regardless of whether it was a single event (washer flood) or one that happens at every rainstorm.

Keep in mind that different molds like different moisture, temperature, and food. One reason that S. chartarum has been "over-reported" as a problem in some studies is that the field "experts" didn't look for lighter molds, and maybe they didn't even carry a flash light. The photo here shows three tape samples being taken from different heights on a laundry room wall. Three different mold species were found, one in each area. Only the lowest black mold was obvious.

In this wall test of three molds which were growing quite close together, I've marked each tape sample so that you can see where it was on the wall. #1 =Stachybotrys chartarum, #2 = Ulocladium chartarum, #3 = Aspergillus sp.. - it is this third mold which, in a larger quantity, would be airborne and more likely to bother building occupants. Yet nearly 100% of home owners and 80% of industrial hygienists and 90% of home inspectors who send mold samples to our lab are going to tape-sample only the "dark mold" on this wall.

Why are there three different genera/species on this drywall? Most likely because each of them prefers a different moisture level in the paper which they're digesting. I can generally track the mold genera up the wall as a function of the moisture gradients in the wall. When a wall has been wet because of wet floor conditions, the drywall and in-cavity wall insulation will be wettest at the wall bottom.

Be sure to review our notes above on use of lighting at Use of a flashlight to find mold since if you don't know exactly how to use a flashlight, as simple as it seems, you're not going to find important light-colored molds in buildings.

Where to Look for Hidden Mold - an Example Using Air Conditioner Air Handling Equipment interiors

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

HIDDEN MOLD, HOW TO FIND
  Photo Guide to Finding Hidden Mold
  Hidden Cosmetic Molds
  Hidden Mold Behind Paneling
  Hidden Mold Between Framing & Sheathing
  Hidden Mold in Flooring & Subflooring
  Hidden Mold in Wall Cavities
  Spotting Hard-to-See Mold
  Wall test cuts to spot hidden mold
  Light colored toxic molds
  Moisture Gradients and Mold
  Other Places to Look for Hidden Mold

Mold Safety Warnings for Do-It-Yourself'ers Planning to Inspect for or Clean Up Mold Contamination

Warning notice

Guidelines defining what's a "large amount" of mold and what's reasonable for a homeowner to handle have been published by several states including New York and California.

People who are allergic, asthmatic, infant, elderly, immune-impaired, etc., should not disturb mold and should not be in the area where mold remediation is being performed. Consult with your doctor, health department or other professional before tackling this job yourself.

More Information on Building Diagnostic Inspections and Repairs

• How to Find and Test For Mold in Buildings - Looking for Mold - A 'how to' photo and text primer on finding and testing for mold in buildings
• Recognizing Mold: What mold looks like mold identification photos to help identify mold - choosing what to sample in buildings
• Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
• Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
• Mold Action Guide: an easy step by step outline of what to do about mold
• How to find mold without hiring anyone, for do-it-yourself'ers
• Associations: Sick House, Sick Building, SBS - Air Quality, Government, Private Associations and Information Resources
• Mold Test Kits - How to Collect and Send Your Own Mold Sample to our mold testing lab
• How to find a mold inspector or test consultant: Directory of IAQ,Sick Building, Mold Allergen Testing, Building Investigation Service Providers
• Meruliporia: the house eating fungus or "poria"
• Mold Investigation Tips for Home Inspectors how to find mold, where to look, what is likely to be important. Advice to building inspectors intending to inspect or test for toxic or problematic mold indoors, mold inspection methods, and mold test methods which are valid or invalid
• Mold Risk Levels in Buildings Based on Visual Inspection - simple visual clues help decide on action
• Mold in Fiberglass Insulation© 2005 comments about a field study in process, & more about health hazards from fiberglass insulation - DJF
• Frequently Asked Questions About Mold -- check this FAQ list & IAQ Site Map to see if you can find a quick answer to your mold concern
• When to hire a professional to inspect for toxic mold or other allergens
• Contact Us to arrange mold/IAQ building on site inspection and testing.

InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.

The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems

Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.

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