Q: What is the name of the dreaded black mould that colonises damp places in bathrooms? Because materials produced to remove the mould do not seem to work, and nor do household bleaches, detergents and solvents, can anyone suggest a remedy other than abrasives?
A: The infamous black mould is the fungus Aspergillus niger. The reason it seems so difficult to eradicate is that the visible black manifestation is merely the exposed structure of the fungus, which is mainly comprised of the fruiting bodies. In addition to this visible material, there is invariably an insidious network of hyphae or mycelia which lie in the substrate of wallpaper or plaster, and feed on the minerals contained within.
Eradication of the mould requires not only the repeated physical removal of the visible growth but the simultaneous use of a penetrative fungicide capable of permeating the substrate and killing off the unseen root structure. The analogy is that of trying to eradicate ground elder or horsetail from your vegetable patch by merely strimming the visible plantlets.
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A: The Aspergillus fungus has been a constant source of annoyance in local council accommodation throughout the nation. It is prevalent where cool, still air deposits condensation next to steel window frames, concrete-screed ceilings water-tank enclosures and similar areas.
Current medical opinion is that this fungus is a major source of allergenic disease and that it produces carcinogenic aerosols, so removal of the unsightly nuisance is also important for health.
I have experienced problems when attempting to remove Aspergillus. Table salt and bleach have only limited success, but I finally effected a permanent solution by washing the affected areas several times with a systemic fungicide available from any garden store. This may not, however, be the safest solution as the fungicide may be as toxic as the fungus.
This week鈥檚 question
Close shave: What function does shaving foam perform during a wet shave, and why is a similar product not necessary for shaving with an electric razor?
K. W. Baldry, Newcastle upon Tyne
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