Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
Ask a Question or Search InspectAPedia
ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT
ACCEPTABLE MOLD LEVEL
ACCURACY vs PRECISION of MEASUREMENTS
ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD
ACTIVITY of MOLD in BUILDINGS
AIR TEST FOR MOLD: ACCURACY
AIR TEST SAMPLING CASSETTE STUDY
AIRBORNE MOLD COUNT NUMBER GUIDE
AIRBORNE PARTICLE ANALYSIS METHODS
ASBESTOS IDENTIFICATION IN buildings
BASEMENT MOLD WATER IMPACT
BIBLIOGAPHY for ENVIRONMENTAL HEALTH, MOLD, IAQ
BIOGAS PRODUCTION & USE
BOD WASTEWATER TEST
BLACK MOLD, HARMLESS COSMETIC
BLACK MOLD, TOXIC & ALLERGENIC
BLEACHING MOLD, Advice about
BOOK MOLD, Moldy Book Cleaning
BOOKSTORE - ENVIRONMENTAL
BROWN HAIRY BATHROOM MOLD
CACTUS FUNGI / MOLD
CAR MOLD CONTAMINATION
CARPET DUST IDENTIFICATION
CARPET MOLD CONTAMINATION
CARPET PADDING ASBESTOS, MOLD, ODORS
CARPET STAIN DIAGNOSIS
CARPET & other STAIN TESTS
CARPET TEST PROCEDURE
CARPETING & INDOOR AIR QUALITY
CARPETING, SELECTION & INSTALLATION
CAT DANDER in buildings
CLEARANCE INSPECTIONS - MOLD CLEANUP
EFFLORESCENCE, Salts & White / Brown Deposits
FIBERGLASS INSULATION MOLD
FLOODS & MOLD CLEAN/PREVENT
FIND MOLD, ESSENTIAL STEPS
FIND MOLD in buildings, HOW TO
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FUNGICIDAL SPRAY & SEALANT USE GUIDE
HUMIDITY CONTROL TO PREVENT MOLD
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
INDOOR AIR QUALITY METHODS COMPARED
INSULATION INSPECTION & IMPROVEMENT
LAB PROCEDURES MICROSCOPE TECHNIQUES
LEAD POISONING HAZARDS GUIDE
Legionella Legionnaires' Disease
Legionella BACTERIA & HVAC Equipment
LIGHT, GUIDE to FORENSIC USE
LP & Natural Gas Safety Hazards
MEDIA BLASTING for MOLD REMOVAL
METHANE GAS SOURCES
MICROSCOPE DIGITAL PHOTOGRAPHY
MILDEW in BUILDINGS ?
MILDEW ERRORS - MOLD PHOTOS
MILDEW REMOVAL & PREVENTION
MOISTURE CONTROL in BUILDINGS
MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD ACTIVITY in buildings
MOLD AGE - Old is the Mold?
MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
Meruliporia Mold Photographs
Recognize Cosmetic Mold
Recognize Harmless Black Mold
MOLD GROWTH ON SURFACES, PHOTOS
MOLD APPEARANCE - STUFF THAT IS NOT MOLD
HARMLESS INDOOR PARTICLES
BASKETBALL MOLD SYNDROME - BBMS
Black stains from soot/thermal tracking
Black stains from animals
Black cosmetic mold
Efflorescence & brown deposits
Efflorescence & white or brown deposits
Sprayed foam insulation
White stuff that is not mold
MOLD ATLAS & PARTICLES INDEX
MOLD BY MICROSCOPE
MOLD in the PETRI DISH, PHOTOS
Mold on Books, Book Conservation
MOLD CLASSES, HAZARD LEVELS
MOLD CLEANERS - WHAT TO USE
MOLD CLEANUP COMPANIES
MOLD CLEANUP, DO IT YOURSELF
MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD
MOLD CLEANUP with BLEACH
MOLD CLEANUP - WOOD FLOORING
MOLD CLEANUP - WOOD FRAMING & PLYWOOD
MOLD CLEANUP HEALTH RISKS
MOLD CLEANUP MISTAKES to AVOID
MOLD CLEANUP - SAFETY WARNINGS
MOLD CLEARANCE INSPECTIONS
MOLD DETECTION & INSPECTION GUIDE
MOLD DOCTORS - ENVIRONMENTAL MEDICINE
MOLD or INDOOR AIR EMERGENCY RESPONSE
MOLD EXPERT, WHEN TO HIRE
MOLD EXPOSURE, FOOD HAZARDS
MOLD EXPOSURE RISK LEVELS
MOLD EXPOSURE STANDARDS
MOLD on or in CARPETS
MOLD ON DIRT FLOORS
MOLD FREQUENCY in buildings
MOLD GROWTH ON SURFACES, PHOTOS
MOLD GROWTH on SURFACES, TABLE OF
MOLD INSPECTORS & MOLD TESTERS
MOLD INSPECTION HOME BUYERS GUIDE
MOLD INSPECTION SERVICE
MOLD INVESTIGATION PROCEDURE TIPS
MOLD INVESTIGATION REPORTS
MOLD KILLING GUIDE
MOLD LAB REPORTS
MOLD LEVEL REPORTS
MOLD LEVELS IN buildings
MOLD by MICROSCOPE
MOLD ODORS, MUSTY SMELLS
MOLD PREVENTION GUIDE
MOLD RELATED ILLNESS
MOLD SAFETY WARNINGS
MOLD SPRAYS, SEALANTS, PAINTS
TEST KITS for DUST, MOLD, PARTICLE TESTS
MOLD TEST METHODS, ACCURACY
MOLD TEST PROCEDURES
MOLD TEST REASONS
MOLD TEST SAMPLE POINT CHOICES
MOLD TESTING & SAMPLING MISTAKES
MOLD TESTING SERVICES
ODORS & SMELLS DIAGNOSIS & CURE
OXYGEN - O2
PAINTS & COATINGS ODORS IN BUILDINGS
PARTICLE SIZES & IAQ
Particulates & Allergens Indoors
Pesticide Exposure Hazards
PET ALLERGEN REMEDIES
PLASTIC CONTAINERS, TANKS, TYPES
PLASTIC HEATER VENT
PLASTIC ODORS-SCREENS, SIDING
PLUMBING SYSTEM ODORS
RENTERS GUIDE TO MOLD & IAQ
SICK HOUSE IAQ QUESTIONNAIRE
SEWAGE BACKUP, WHAT TO DO
SEWAGE BACKUP TEST & CLEANUP
SEWAGE BACKUP PREVENTION
STAIN DIAGNOSIS on BUILDING INTERIORS
STAINS on INDOOR SURFACES: PHOTO GUIDE
STAINS & Thermal Tracking
TECHNICAL & LAB PROCEDURES
TEST KITS for DUST, MOLD, PARTICLE TESTS
Thermal Expansion Cracking of Brick
THERMAL EXPANSION of HOT WATER
THERMAL EXPANSION of MATERIALS
THERMAL IMAGING, THERMOGRAPHY
THERMAL IMAGING MOLD SCANS
THERMAL MASS in BUILDINGS
THERMAL TRACKING & THERMAL BRIDGING
TRAPPED MOLD BETWEEN WOOD SURFACES
TRIM, INTERIOR INSTALLATION
TRAPPED MOLD BETWEEN WOOD SURFACES
TRUSS UPLIFT, ROOF
TRUSSES, Floor & Roof
Urea Formaldehyde Foam Insulation UFFI
URETHANE FOAM Deterioration, Outgassing
UV LIGHT BLACK LIGHT USES
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS
VINYL CHLORIDE HEALTH INFO
VINYL Siding or PLASTIC Window ODORS
Volatile Organic Compounds VOCs
WALL SIDING TRIM & FINISHES
WALL FINISHES INTERIOR
WALL CONSTRUCTION BARRIER vs CAVITY
WATER BARRIERS, EXTERIOR BUILDING
WATER ENTRY in buildings
WATER ODORS, CAUSE CURE
World Trade Center Collapse Dust Photos
How to recognize harmless black or dark colored indoor mold. When investigating a building for a mold problem, you can save mold test costs by learning how to recognize Harmless Black Mold but which is often mistaken by some un-trained or inexperienced "mold inspectors" or "mold remediators" as more serious contamination which they call "toxic black mold".
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Some black mold in buildings arrived on the framing lumber and is harmless both to humans and to the building materials on which it is found. Often a visual inspection for certain clues (discussed below) can make you very confident of when mold appeared on lumber and what sort it probably is.
Interrupted Mold Growth Confirms No Active Mold Growth on Indoor Framing Lumber
If you are reasonably sure that you’ve got mold like Ceratocystis/Ophistoma that came in on the lumber at time of framing, it’s harmless and also is not likely to grow into a bigger problem. In fact indoors we have never found Ceratocystis/Ophistoma mold in an active growth state inside of a building – we imagine that it needs different (wetter) growing conditions than found in a building. Indoors, even if Ceratocystis/Ophistoma mold was alive, it’s cosmetic-only. Cleaning or removal of a cosmetic mold is entirely optional and would be done (or not) in a building for reasons of appearance, not health.
Leave Cosmetic Mold Alone on Dry Indoor Framing Lumber
If the cosmetic mold you see is like that in our photographs on this page, that is, there is no evidence of active mold growth and the mold obviously came from the lumber yard and the lumber is dry, or kiln-dried, and the environment where the wood is found has remained dry, the mold is only cosmetic and no action is necessary.
Clean Moldy Pressure Treated Framing Lumber that is to be Used Indoors
When using pressure-treated lumber for interior framing, clean off any visible mold. Simple power-washing would suffice
This step is not necessary and would be inappropriate for the same lumber when used outdoors, such as for a deck or an entry stair. But inside, such lumber may be used for sill plates or in some cases we have seen it used to re-frame a rotted floor over a wet crawl space.
Importing a large Aspergillus sp. colony on the floor framing surface over a crawl space provided an immediately-detectable high level of airborne Aspergillus sp. in the room above this area, as these spores move easily in convection air currents moving from the crawl area up through the building.
For this reason, if visibly moldy treated lumber is to be used in indoor construction we recommend that it be physically cleaned first - such as by using a power washer and deck cleaning solution. "Sterilizing" such lumber to try to "kill" mold is unnecessary and inappropriate.
Just clean the moldy lumber, don't try to sterilize it. (See MOLD KILLING GUIDE for details of why killing mold is not the most useful approach.)
What if I remove "cosmetic" indoor mold and it reappears? If you remove a mold you believe was "cosmetic" and later you find new mold growth in that area:
ANY indoor building condition that produces or has produced new or recurrent indoor mold growth on building surfaces means there is also a risk of both visible and hidden problematic molds of genera/species other than just cosmetic molds. Even when you test and identify a specific mold on a building surface you should not assume that the mold you've identified is the only problem, or even the most serious mold problem in the building, unless you have also completed a through, expert diagnostic inspection of the building.
To prevent problem indoor mold your focus should be on watching for and correcting leaks or moisture problems in your building. For details on how to prevent indoor mold growth in buildings see:
In summary about cosmetic indoor mold: If at present you’ve found evidence of mold growth inside of a building other than Ceratocystis/Ophistoma then it’s moisture and leaks that need your attention, not the Ceratocystis/Ophistoma.
Frequently Asked Questions (FAQs) about cosmetic mold & sapstain molds on wood & lumber
Question: I am a chainsaw carver who deals with blue fungi mold in logs - how can I get rid of blue fungal growth on my wood?
I am a chainsaw carver who deals with blue fungi mold in logs; I have attached a photo. Can you provide information on this and getting rid of it; I have numerous colleagues who also like to know! - S.N.
Nice photo, S.N. I can't ID a mold fungus from that or any photo alone (only a fool would claim to). That said, it's indded possible we're looking at a blue sapstain such as Ceratocystis sp. or Ophistoma sp. But before we go messing with bleach - a cosmetic repair that has its own problems, let's run through some diagnostic questions about wood stains and blue sapstain fungal growth in your wood.
1. Let's make sure it's not some contaminant that fell onto the wood, or that a fungal growth is not being encouraged by how wood is stored or by something else left lying atop the wood that traps or holds water. In the photo the stain looks as if it has run from water - was this log slice standing vertically or on an angle?
Normally mold growing on wood would begin from a spore landing on the surface, and would grow often in a rounded pattern out from that point; spores or fungi don't land on wood in a dead straight line.
Sapstain fungal growth (bluestain) may indeed not look random on the wood, as our photo from Winfield shows at left. The fungal growth is probably following the cellular structure of the wood itself from where the first inoculating spore(s) found a home.
Our other photos (below) show additional typical mold growth patterns on wood & lumber.
But something straight that was placed on the wood might indeed cause straight-line staining. That makes me wonder if your stains are in fact being caused by stickers you are using to separate slabs of wood you are trying to dry (stickers themselves are too wet or are a poor material choice), combined with a slow drying process, possibly aggravated by storing your wood exposed to rain and in warm weather. Woodweb discusses sticker stain and provides some excellent advice if this is the root of your stains.
2. Let's do a little testing for wood penetration of the stain. Have you tried cutting a sample with a gouge chisel or knife?
Does the stain extend into the wood grain or is it mostly surface? I suspect you'll reply the stain has penetrated the wood surface (whch these sapstain fungi certainly do.)
3. Does the stain always appear in this pattern on all of your wood samples? Take a look at the example photos I include from our two reference texts.
4. Is this stain in the wood when you buy it or cut down the tree, or is it appearing on the wood while you have it in storage, perhaps drying?
5. I could examine (pro bono) both a wood gouge sample of stained (and a control of not-stained) wood (just a 1/2" square would do) and a tape sample if you can get the material onto a clear adhesive tape - see MOLD TEST KITS for DIY MOLD TESTS -
If you are already certain it's a fungus it's probably blue sapstain such as one of the two species I've cited above, and that I discuss online at Recognize Harmless Black Mold, you'll see in my photos that the mold does not grow on wood surfaces quite like the pattern in your photo.
My reference texts on this topic, by Wingfield et als, has (p142) sapstain photos in black and white.
I'm posting here copies of some reference in-situ mold on wood photos for your comment (or comments from other readers) along with similar images from Wang & Zabel the other useful text for this topic.  
Remedies for Sapstained Logs, Log Slices, Wood or Lumber?
Unfortunately if the bluestain is deep into the wood it's almost impossible to remove completely. Worse, we have read that some fungi may be present but not visible as a stain until the wood has been further dried & cured.
I've had some success with detergent followed by careful treating with bleach solution, and a thorough washing off a wood surface to reduce or eliminate stains (and bleach odors) in a finished product. But deep stuff is hard to deal with. Selection of wood not already visibly infected, and prevention of mold growth on stored wood by attending the conditions on which we store it may be in order. I know that may be tough for a chainsaw wood carver, since you work with big sections of logs that remain outdoors. Let's get more confident in our diagnosis and then pursue remedies further.
Blue stain or sapstain prevention (& sticker stain prevention) in or on wood
Handling moisture, both in the wood itself, and in the environment where wood is stored for drying and before use, is the single most effective thing you can do to reduce fungal growth on and in the wood itself. Speeding the wood curing or drying process, including storing wood on separation stickers, off the ground, and under cover (protected from rain and snow but not in an airtight enclosure) could make a significant difference in the rate of bluestain or sapstain occurence on your wood.
If your wood stickers are not absolutely dry (below 10% moisture) they could be causing sticker stain as we discussed above and as I suspected from the stain pattern in your photo.
If your wood is not stained when you first rough-cut it, you may be able to retard if not prevent sapstain growth by dipping the log sections in a fungicidal chemical (or enzyme). The problem is that the wood may be inoculated and your treatment may not penetrate the lumber adequately. That's why pressure-treated wood is "pressure treated" (though the pressure treatment target is not fungi and the chemicals used don't seem to retard fungus growth in that case).
Questions & answers or comments about cosmetic black or dark colored mold in buildings.
Ask a Question or Enter Search Terms in the InspectApedia search box just below.
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
Online Mold & Particle Identification Aids at InspectAPedia.com