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Advice from Commercial Painting Experts on Fixing Mould

Aug 27, 2013

Tips from commercial painting professionals to help with your DIY painting problems. Programmed Property Services are the largest employers of painters in Australia and New Zealand. We have a huge knowledge base we can draw from to answer any painting related question. This month, we look at how to fix areas affected by mildew and mould.

commercial painting

by Nathan D’Couto

How to identify mildew and mould
Typically, mould is either black, grey or brown spots on the surface area of paint. Mildew is most common on external painted weatherboards and is very similar in appearance.  Both are caused by damp and little, or no, exposure to sunlight. This is very common on the underside of external eaves and weatherboards in shaded areas, as well as in wet areas like laundries and bathrooms commonly caused by poor ventilation.

Other causes of this problem include:
* Poor quality paint not containing adequate amounts of mildewcide. This is an additive normally added by paint manufacturers designed to inhibit mold and mildew growth.
* Failure to prime bare wood before painting.
* Applying paint over existing mould or mildew which has not been removed.

Safety first: mould is a fungus and when airborne can be harmful to children, the elderly, those with a weakened immune system, or other medical conditions such as respiratory conditions like asthma. Ensure you have a good quality dust mask or respirator, full length clothing, rubber gloves, and goggles.

Start by testing the area to ensure it is mould or mildew. Apply a few drops of general undiluted washing bleach to the area in question. If the discoloured area starts to disappear and the paint surface reappears then we are definitely working with mould or mildew.

Mix one part household bleach with three parts water and start applying it to small areas using a scouring pad. Keep scouring the area until all evidence of the mould is removed.  Then rinse the area with water. If treating an external area sodium hypochlorite can be used at a 1:3 ratio. For much faster results rinse with a pressure/power washer.

Our Paint Pros recommend using premium grade oil based sealer / undercoat to all affected areas. Most paint manufacturers say you can apply their products directly without an undercoat over these areas, but our paint pros tell us if you don’t want the mould to reappear use oil based undercoat first.

After this step apply 2 coats of premium acrylic paint suitable for the area. There are many paints on the market that claim to resist mould. Our commercial painters say any premium grade semi gloss acrylic paint will do the job if the area is prepared and primed well prior to top coating. For external areas a suitable external grade semi gloss or gloss acrylic is recommended.

To prevent mould from reappearing ensure your wet areas are well ventilated (install an exhaust fan to improve circulation). For external surfaces, washing painted surfaces with a mild detergent every 12 months will almost guarantee you will have a mildew free surface.

Programmed Property Services are the largest employers of painters in Australia and NZ. With over 700 fulltime painters and 40 apprentice painters, we have a huge knowledge base we can draw from to answer any painting related questions.

So if you’re facing a paint problem or want to know how a commercial painting professional would do a particular task, why not ask us?

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