What Does Black Mold Look Like? How to Identify It

Quick answer: Black mold (Stachybotrys chartarum) typically appears as dark greenish-black or charcoal patches with a slimy or wet-looking sheen when active, drying to a powdery texture. It grows in irregular blotches or spreading circular clusters on chronically damp, cellulose-rich materials — drywall, wood, ceiling tiles, and paper backing — and it usually comes with a strong musty smell. See something suspicious? Call (888) 245-6962 — free, 24/7 — for an IICRC-certified inspection.

Color, Texture, and Pattern

Color: dark green-black to charcoal. True black mold rarely looks jet black — there's usually a green or gray cast. Colonies can also appear dark gray with lighter edges where growth is newer.

Texture: actively growing colonies look slimy, wet, or slightly glossy because Stachybotrys produces a wet spore mass. As an area dries out, the same colony turns matte and powdery or sooty-looking.

Pattern: irregular blotches and spreading clusters rather than the even film you get from dirt. Look for growth that follows the shape of a water stain, radiates from a corner, or forms a distinct line where water wicked up drywall.

Where it grows: drywall and its paper backing, wood framing and subfloor, ceiling tiles, cardboard and paper stored in damp areas, insulation, carpet backing — all cellulose-rich materials that stayed wet for days or longer.

Black Mold vs. Look-Alikes

• Mildew is flat, powdery, and usually white, gray, or light green — it sits on the surface and wipes off relatively easily. Black mold penetrates and won't fully wipe away.
• Dirt or dust buildup is uniform, follows airflow patterns, and wipes clean with a damp cloth without returning.
• Soot or smoke residue is dry, greasy or powdery, spreads evenly on surfaces near heat sources or vents, and smells like smoke rather than must.
• Efflorescence on basement walls looks like a white or gray crystalline powder — it's mineral salt left by evaporating water, not mold. It brushes off dry and dissolves in water. (It does, however, mean moisture is moving through that wall.)
• Black stains from water alone are flat discoloration without texture and without a musty smell.

Where It Hides When You Can't See It

• Inside wall cavities near old plumbing leaks — often visible only as a stain or soft spot on the room side
• Under flooring — beneath carpet pad, laminate, or vinyl where water was trapped
• Behind bathroom fixtures — vanities, toilets, and tile with failed grout
• Crawl spaces and attics — the most common whole-house mold sources, and the least visited rooms in any home
• HVAC systems — drip pans, coils, and ductwork, which then distribute spores everywhere

What to Do When You Find It

Don't disturb it. Scrubbing, sanding, or demoing a colony without containment releases spores through the whole house — the most common way a one-room problem becomes a whole-home problem.

Judge the scale. Under ~10 square feet on a hard, non-porous surface is reasonable DIY (safe methods here). Larger areas, growth on drywall or wood, hidden growth, HVAC involvement, or any mold following flooding or sewage should be handled professionally.

Fix the water. Whatever kept that surface wet — leak, condensation, seepage, poor ventilation — must be corrected or the mold returns.

Call (888) 245-6962 — free, 24/7 — and get an IICRC-certified mold professional to identify what you're looking at. More: full remediation process and cost · black mold removal guide