Photo of mold on bedding  (C) Daniel Friedman Mold In-Situ: Photos of Mold on Surfaces - Group 6
Appearance of Mold on Different Materials & Surfaces.

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Photographs of mold growth in buildings:

Here is an extensive photo guide to mold growth on things found around the home or in it including mold on plastic or rubber garden hose, mold on glass surfaces such as window panes, mold on hardboard used indoors, mold on houseplants, mold on insulating boards and sheathing, mold on or in fiberglass insulation, mold on or in foam insulating boards or spray foam, moldy mattresses and bedding, even pillow-cases, mold in metal stud walls, mold on metal surfaces such as filing cabinets, mold in modular homes or other modular buildings.

What does mold look like growing on various building & other material surfaces? Here is an online reference photo library of various kinds of mold as it is found growing on a wide range of surfaces and materials found on or in buildings. These photos of mold on indoor various materials or "mold growth substrates" may help you recognize mold in buildings, recognize probably-cosmetic mold, and recognize stuff that is not mold and does not need to be tested.

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.

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Pictures of Mold on Various Building Surfaces and Materials

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to return to the index / list of photographs of the appearance of mold on various building materials & contents.


  4. MOLD on HARDBOARD, Masonite™
  6. MOLD on INSULATING BOARDS, Homasote™ Celotex™
  10. MOLD on METAL SURFACES, Filing Cabinets, Stainless Steel Sink, Steel Columns

Photographs of mould found on the surface of items, materials, & surfaces found indoors

[Click to enlarge any image]

Mold on Garden Hose

Photo of mold on a garden hose (C) Daniel Friedman

This photograph illustrates mold growth on a common garden hose.

Also see MOLD on RUBBER for other examples of mold growth on rubber or see MOLD on VINYL WINDOWS for examples of mold growth on vinyl.

Mold on Gas Fireplace Ceramic Backer

Green & black stains on ceramic surface of gas fireplace (C) InspectAPedia SH Question:

This fireplace panel where the flames go is green and black, it is not fuzzy and cannot scrape with fingernail. It does not fade with bleach or mold remover…just curious, do you know if this is a color from flames burning over time. The apartment does not have any mildew or dampness under rug (replaced it) and the walls are not moldy behind wallpaper (removed and painted) and it is dry.

Do you know if this is a discoloration that old fireplace inserts get? I could not find this addressed on your website.

I called an antiques dealer in Wash. DC as he had photos of similar fireplace inserts in his store for sale and says its wear. - Anonymous by private email 2016/07/29


It's an odd pattern that doesn't look flame-related; but if the stains were from algae or mold on a ceramic surface I'd think they'd at least lighten with use of a cleaner or bleach solution. The photograph itself is insufficient, and your description of inability to remove any of the green and black stain areas by cleanign or wiping argues against it, but the pattern and colors do look a bit like mold growth.

Please see GAS FIREPLACE CERAMIC STAINS where we discuss this gas fireplace and its stains in detail. Although the pattern, texture, and color of the deposits in this gas fireplace look like mold in the photo, without a laboratory test of a surface sample of these deposit mateirals we cannot know for sure what they are and thus we won't be sure about how to remove them nor whether or not the deposits indicate other unsafe conditions.

At MOLD TEST KITSI describe the method I recommended to you for collecting tape samples suitable for settled dust, mold or other particle examination tests. You can use this procedure for surface dust or debris analysis byt any qualified mold or forensic laboratory.

Watch out: If gas fireplace deposits are sooty and are being caused by a burner or combustion air defect the system is unsafe and should be left shut down until it can be inspected and reparied; combustion defects on gas fueled appliances risk fatal carbon monoxide poisoning.

Mold on Glass Surfaces

Mold found "growing" on glass is most likely growing on organic deposits that are on the glass surface like the overflows on these wine brewing bottles. We have also observed more serious damage to glass lenses on cameras and binoculars exposed to mold. In that case mold is attacking coatings on the lenses.

Mold growth on home brewery wine jubs (C) Daniel Friedman Mold growth on glass surfaces of wine bottles (C) Daniel Friedman

Mold on Hardboard, Masonite™

At below right (click to enlarge) you can just see white fungal mycelia that permeated this sample of hardboard siding that had been used as wall paneling in a church's damp basement.

Mold contamination on hardboard and masonite type products (C) Daniel Friedman

Mold on Houseplants - It's Mildew

Mildew on a Jasmine plant, closeup (C) Daniel Friedman Mildew on a Jasmine plant, closeup (C) Daniel Friedman

Above we show white mildew on the leaves of a Jasmine plant that moves between indoors and outside at our house. Left outside in the sun and not over-watered the plant generally doesn't have a mildew problem. But indoors, over-watered, or outdoors in shade and in rainy weather, the leaves can quickly become covered with white mildew.

Mildew only grows on living plants so if you see white mold on your shoes or somewhere else, unless they're made out of green leaves, it's not mildew.

For details on what to do about cleaning off or removing mildew, and how to both cure and prevent

Mold on Insulating Boards, Homasote™ Celotex™

Photo of mold on wood fibergboard sheathing or insulating board (C) Daniel Friedman

This photograph illustrates mold growth on insulating board product whose principal ingredient is wood fibers.

Mold on Insulation, fiberglass, foam

Mold on Insulation Kraft Paper Facing

In our photo at below left we see black mold and other mold growths on the kraft paper facing of fiberglass building insulation. Our black mold photo on kraft paper found on a different section of building insulation (below right) illustrates mold colonies that do not always grow in round colonies shown other mold photographs.

Dense mold contamination growth on fiberglass insulation kraft facing (C) Daniel Friedman Mold contamination growth on insulation kraft facing paper (C) Daniel Friedman

At below left our photograph shows mold on the wrap covering fiberglass insulation used on piping.

Watch out: black stuff is not always mold: at below right our photograph of a black streak across a batt of fiberglass insulation is an example of a marking that a client thought was mold contamination. The black material was a pigment, not mold, and was associated with the product's manufacturing process.

Watch out again: However other samples of this fiberglass batt were found to be contaminated with Aspergillus sp. - it was not visible to the naked eye.

Mold growth on fiberglass insulation batt coverl (C) Daniel Friedman Black insulation binder pigment mistaken for fiberglass insulation mold (C) Daniel Friedman

More building roof insulation mold in a different growth pattern is below.

Moldy building insulation (C) InspectApedia reader contributed

Details about fiberglass insulation contamination, testing, and research begin

The following photograph illustrates mold growth on asbsestos pipe insulation.

Mold growth on fiberglass pipe insulation, plastic covering surface (C) Daniel Friedman

More photos of moldy pipe insulation are at MOLD on ASBESTOS PIPE INSULATION

Mold on Mattresses, Bedding

Wet mattress (C) D Friedman Photo of mold on bedding  (C) Daniel Friedman

The mattress and bedding photographs shown above along with more images are discussed at MOLD ON CLOTHING, CLOTH, BEDDING

Mold on Metal Stud Walls

Below are photographs from two different buildings each of which suffered significant mold contamination in the metal wall stud cavity. Both buildings conducted water around the walls from a single leak point source when water flowed in the metal sill plate.

Mold on drywall at metal stud wall, rusted stud channel (C) D Friedman Memnoniella echinata mold contamination of drywall inner surface in cavity of a metal stud wall, NYC apartment (C) Daniel Friedman

The severe mold contamination in the wall cavities shown above was detected by first making a very small test cut in a suspicious area (where flooring was buckled).

See HIDDEN MOLD in CEILINGS / WALLS for details.

Mold on Metal Surfaces, Stainless Steel sink

It's less surprising to find mold growth on a stainless steel surface if you consider that the surface may have had a film coating of food or other organic material. The moldy stainless steel sink in these photographs was in a home that had been left flooded for two or more weeks.

Mold growth on stainless steel kitchen sink  (C) D Friedman Mol dgrowth on stainless steel surfaces (C) Daniel Friedman

Below we illustrate white mold growth on the painted surface of a concrete-filled steel Lally column in the basement of a home examined by an InspectApedia reader (below left), and mold growth on the painted surface of a metal filing cabinet that was inspected in the flooded basement of a White Plains NY office building (below right).

White mold on steel Lally Column (C) InspectApedia M.T. Mold growth on a metal filing cabinet (C) Daniel Friedman

Reader Question (about the white mold-like material on the steel column shown at above left):

I was hoping you could help me identify a growth that I just saw yesterday on a house I was touring. It was located on the steel beams in the basement only, so I thought that was odd, as some things I have read indicated that mold does not really like to grow on metal (not a food source).

There is no other evidence of water damage in the basement. Any ideas as to what the growth in the attached pictures could be? - M. 15 Feb 2015

Reply: most likely this is a white fungus growing on the painted surface of a steel Lally column

There are two candidates for this white material:

Likely: a white fungus (mold). You're right that most molds don't like to grow directly on steel but this is painted steel and plenty of fungi like various paints. In fact I've collected mold samples even from stainless steel and glass surfaces, though IMO in those cases it was actually living on a coating on that surface such as a lens coating or a food, dust or debris coating that contained organics.

Some white or light coloured molds such as (but not limited-to) members of the Penicillium or Aspergillus genera can produce small, easily-airborne toxic or pathogenic mold spores that present a health risk to building occupants.

Unlikely: a mineral salt (effloresence) that is unlikely unless the Lally column has been wet AND has numerous pinholes right through the steel (effloresence is a mineral salt left on surfaces when salts leached by moisture from a masonry material such as concrete are left on the surface)

When I magnify your image I see what looks like a fungal growth material but my view is limited. A close-up examination by high power magnifying glass would perhaps reveal either an organic or fungal structure or crystalline structure characteristic of effloresence. Without a tape sample with which in our lab we could make a definitive particle identification, I'm guessing that the white material on the steel column in your photo is a white fungus.

What does this mean to you? Maybe not much, but I'd be alert for high moisture in the basement where these posts were found since in either case this white stuff is a moisture indicator. Why "just" on these posts?

Reader follow-up: is this white fungus dangerous?

... if it is indeed a white fungus- is it hazardous? The house is bank owned and otherwise in great shape, but the fact that it's bank owned means I'll be responsible for any kind of remediation and also stuck with the outcome.


... you know what I'm going to answer so I'll be brief:

Only a fatuous fibber or fool would pretend to tell you that s/he can identify the genera and species of white stuff that looks like mold on a Lally column based on a photo, much less to assert just how safe or dangerous it is. There are about 1.5 million mold species, about 80,000 that have been well studied, and probably thousands of species that are white, and perhaps hundreds that we know about and that are white and that might grow on a painted steel surface.

The total area of mold represented by white mold-suspect material on a Lally column is likely to be trivial - not sufficient by itself to merit professional treatment (it's less than 30 sq.ft. of contiguous mold). Remove it, clean the surfaces, using any household cleaner and taking common sense personal protection (eyes, skin &c)

General safety advice:

1. Don't put a dirty mold-covered finger in your eye - you could get an eye infection

2. Heed my warning that the conditions that produced the mold you can see may have produced more important mold growth that you haven't seen. Look for the possible causes of water entry, leaks, high humidity, condensation - and fix those.

OPINON: a house that is bank-owned is more likely than others to have been left unattended - which can explain leaks, moisture, condensation - and to have been cleaned and prepped for re-sale by a contractor who is charged with making things look good at the lowest cost. If you find an inspector who has no conflicts of interest, and who has your interest in mind, s/he ought to be able to reduce for you the risk of surprises - reduce, not eliminate them.

Mold on & In Mobile Homes, Doublewides, Trailers

Extensive mold contamination in this mobile home renders it uninhabitable (C) MA

Above: extensive whit


Mold in Modular Homes

Mold may be found in surprising locations in modular homes depending on the home's delivery conditions and construction history.

Residential modular home structures include cavities between floors and some walls that an inexperienced inspector may fail to consider. Knowing that water had entered this modular structure we obtained permission for some destructive inspecting that helped track how water had moved through the building.

Leaks & mold growth in wall cavity, modular home exposed to rain during delivery (C) D Friedman Photo of mold on modular home wall cavity surfaces (C) Daniel Friedman

For details about the causes of and detection of mold contamination in modular constructed homes

Also see MOLD GROWTH on SURFACES, TABLE OF our table of mold growth locations in buildings

where we include MOBILE & MODULAR HOME MOLD

Mold in Motor Oil & Lubricants

Mold on cardboard boxes in a wet basement (C) EMW

Above we see mold on wet cardboard boxes used to store Quaker State motor oil, contributed by reader [Anonymous] 2016/08/25 by private email. The reader commented and then asked:

Might be from a leak from neighbors bathroom. No product leaked out of containers in boxes, but was asked if mold and mushrooms can grow in clean motor oil.

Motor oil, itself toxic to most living organisms, will not be found supporting visible mold growth. On the other hand, it is not accurate to say that absolutely no microorganisms "grow" in or function in motor oils. Walker (1975) discussed the effects of thermophilic bacteria and mold on the break down of motor oil of the type likely to be found in nearshore wastewater discharges and wastewater. See


CONTACT us to submit photographs of mold growth on other man-made or building-related materials.


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Or see MOLD APPEARANCE on VARIOUS SURFACES - INDEX to return to the full list of photographs of the appearance of mold on various building materials & contents.

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MOLD GROWTH on SURFACES, PHOTOS_GROUP_6 at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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