I recently laid some 400x400x15mm indonesian marble, area of 90m2 approximately 1 in 5 of the tiles had mould through the tile in varying degrees right through the body of the tiles and upon unpacking the material from its boxes I could smell the mould. Can anyone enlighten me on the origins of such mould and how it can or if it needs to be dealt with. (Anonymous)
ASAA
Australian Stone Advisory Association Ltd
Moulds require a relative humidity of around 60% and temperatures of +20degrees c to grow. Some moulds can be extremely dangerous and sometimes fatal. The musty smell was you inhaling the possibly toxic mould spores. They require still air and darkness or low light. Packed in boxes in tropical Indonesia would be a perfect environment for mould to grow. 1 part bleach to 3 parts water is recommended to kill moulds. Not a good idea on marble because of the acid but vinegar and water does the job as well. Dr Heike Neumeister-Kemp or Dr Peter Dingle of the Murdock University in WA can provide you with specific answers on mould problems. Now the tiles have been laid and exposed to moving air sunlight and would now be drying out I doubt that the mould would survive. As per mould on grout the mould can be dead but the staining can be left behind. Hydrogen peroxide or bleach may be the way to go to try and bleach out the discolouration. As with everything Test Test Test first. (fabfil)