What causes mildew?

Mildew is an airborne fungus that can grow on most surfaces, including painted ones. It can be black, gray, green or brown in color, and may look like dirt on the surface.

Mildew requires moisture, warmth, a food source and a surface in order to grow; the following conditions will increase the chances of mildew growth:

• Warm, humid conditions
• Poor air circulation
• Protection from direct sunlight
• Proximity to existing mildew

What causes peeling?

Peeling is the final result when a paint film loses its adhesion to the substrate. Peeling may occur between coats of paint (intercoat failure), or all the paint coats may peel from the underlying substrate (total film failure).

• Poor surface preparation - The following surface conditions may cause peeling if not prepared properly:
  1. Slick, glossy or non-porous surfaces
  2. Dirty, greasy or grimy surfaces
  3. Chalky surfaces
  4. Rusty or corroded metal
  5. New alkaline masonry
  6. Porous, weathered wood
  7. Galvanized metal
  8. Unsound surfaces (like loose, crumbling masonry, or surfaces with peeling or flaking paint or multiple paint coats)
• Application conditions - Peeling can also occur if the paint is applied in less than ideal conditions:
  1. If the temperature is too hot or cold, incomplete film formation may result in poor adhesion.
  2. If the paint is applied to a wet or damp substrate, or applied when the humidity is too high.

What do I do about peeling and how do I avoid it?

1. Remove the peeling sections of paint, by sanding, wire brushing or scraping.
2. Properly prepare the substrate:
   • Metals: use a red/yellow zinc oxide
   • Woods: use Sissons Universal Undercoat
   • Concrete: use Sissons Concrete Primer
3. Repaint the surface when the temperature and humidity is suitable for painting.
   • Metals: Alkyd or Oil-based paint
   • Woods: Sissons Super Gloss
   • Concrete: Sissons Super Matt or Weather Guard