Bleaching Does Not Kill Mold

Chlorine Bleach (sodium hypochlorite 6%) does not kill mold. Why?

Mold’s hyphae (root structures) actually grow into wood and drywall like roots. The hyphae are not killed by bleach because bleach’s ion structure prevents chlorine from penetrating into porous materials such as dry wall and wood. It stays on the outside surface, whereas mold has protected enzyme roots growing inside the porous construction materials. When you spray porous surface molds with bleach, the water part of the solution soaks into the wood while the bleach chemical sits atop the surface, gasses off, and thus only partially kills the surface layer of mold while the water penetration of the building materials fosters further mold growth.

Chlorine bleach causes long term breakdown of wood products like studs, sheathing, plywood, OSB, and other building materials over time.

Chlorine Bleach is NOT a registered EPA mold killing product.

You can verify it yourself when you are unable to find an EPA registration number for killing mold on the label of any brand of chlorine bleach. Why not? Because it is not effective at killing mold as other EPA approved chemicals.

University Study Discovers Bleach is Ineffective at Killing Mold on Wood and Other Porous Surfaces.

“While bleach is often recommended for remediation of surface mold on wood and other porous surfaces, our [university research study] study results illustrate that the treatment does not eliminate the surface microflora,” is the conclusion of th e Oregon State University study of the effects of chlorine bleach on mold growth on Douglas fir wood [an important timber crop in the state of Oregon]. The research study was conducted by Professor Jeffrey Morrell, Dept. of Wood Science, Oregon State University, as assisted by Adam Taylor [graduate research assistant] and Camille Freitag [Senior Research Associate], as published in Forest Products Journal, 54:4, 2004.

To read the Forest Products Journal Research Study on the effectiveness of chlorine bleach Click Here.

What does the EPA have to say about using bleach to kill mold?

“The use of chlorine bleach is not recommended as a routine practice during mold cleanup.” from the website


1) Bleach does not kill mold.

2) Bleach was not designed to kill mold, and has never been sold or EPA registered to do so.

3) There are no professional, certified mold remediators who use bleach for killing mold.

4) Bleach cannot penetrate into mold’s tiny hyphae (roots), but the water part of the formula will, thus fostering more, even stronger mold growth.

5) Bleach is a very destructive chemical, and literally eats away at the surfaces it’s applied to.

6) Chlorine begins to break down quite quickly and consistently after Bleach is manufactured, so within a short period of time (2 to 3 months), whatever minute mold cleaning abilities the product had are dwindled away as it waits to be shipped to stores and purchased.

7) Bleach’s off gassing is hazardous to all flora and fauna, and mixing bleach with any other chemicals can produce extremely toxic vapors. It’s generally considered unsafe for use in cleaning mold.

Besides causing a major business interruption, a mold problem can present a serious health risk for people exposed at your commercial property. Mold infestations can be caused by minor water intrusions, like a slow roof leak or loose plumbing fitting. Every hour spent cleaning up is an hour of lost revenue and productivity.

If you have a mold problem, call Greene Environmental who will respond quickly and work fast to manage the situation.

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