Why Bleach Doesn’t Work on Porous Materials
Bleach (sodium hypochlorite) is effective at killing surface mold on non-porous materials like tile and glass. But for porous materials (drywall, wood, grout, concrete) it fails because:
- Bleach is primarily water (typically 90%+ water by volume)
- The water component penetrates porous materials; the chlorine component does not
- Mold roots (hyphae) grow deep into porous materials; surface treatment doesn’t reach them
- The moisture from bleach can actually feed the hidden mold colonies
- Bleach removes the color from mold, making it appear gone while the colony remains alive
What Professional Remediation Uses Instead
- Antimicrobial agents: EPA-registered products formulated to penetrate porous materials and kill mold at the root level
- Encapsulants: Sealants applied after cleaning that prevent regrowth on semi-porous surfaces
- Physical removal: For heavily contaminated porous materials, removal is more effective than any chemical treatment
- HEPA containment: Negative air pressure and HEPA filtration prevent spore spread during treatment