Microscopic spores will remain even after brushing. Kill these with a solution of bleach, or if the wall suffers persistently from fungal growth, use a proprietary fungicide, available from most DIY stores.
Using a bleach solution
Mix one part household bleach with four parts water. Paint the solution onto the wall using an old paintbrush, then 48 hours later wash the surface with clean water, using a scrubbing brush. Brush on a second application of bleach solution if the original fungal growth was severe.
Using a fungicidal solution
Dilute the fungicide with water according to the manufacturer’s instructions and apply it liberally to the wall with an old paintbrush. Leave it for 24 hours then rinse the wall with clean water. In extreme cases, give the wall two washes of fungicide, allowing 24 hours between applications and a further 24 hours before washing it down with water.
Removing Efflorescence from Masonry
Soluble salts within building materials such as cement, brick, stone and plaster gradually migrate to the surface along with the water as a wall dries out. The result is a white crystalline deposit called efflorescence.
The same condition can occur on old masonry if it is subjected to more than average moisture. Efflorescence itself is not harmful but the source of the damp causing it must be identified and cured before decoration proceeds.
Regularly brush the deposit from the wall with a dry stiff-bristled brush or coarse sacking until the crystals cease to form – don’t attempt to wash off the crystals; they’ll merely dissolve in the water and soak back into the wall. Above all, don’t attempt to decorate a wall which is still efflorescing, and therefore damp.
When the wall is completely dry, paint the surface with an alkali-resistant primer to neutralise the effect of the crystals before you paint with oil paint; water-thinned paints or clear sealant et the wall breathe, so are not affected by the alkali content of the masonry, some specially formulated masonry paint can be used without primer.
If you have any further questions please call our office.
We want you the reader to write to us on, any Building matters and questions or if you seek advice, we will gladly answer any topic that you wish us to discuss, so please send your letters to “BHIS” C/O. 17 Battye Road, Kardinya, W.A. 6163. Or fax/ph. (09) 331-3031