Microclimates (immediate exposure environments)

From the Resene paint and decorating problem solver

Learn about the microclimates that cause the breakdown of protective coatings and what to do about them.

The microclimate effect

The Microclimate effect
The microclimate effect is illustrated by the weathering pattern on these coastal (severe region) warehouse doors.

Types of microclimates or typical on-site factors that cause the breakdown of protective coatings include the following:

Damp locations not dried out by sunlight
Exposure to marine atmospheres
Concentrations of industry
Contamination from airborne fertilisers and other chemicals
Alkaline or acidic aqueous fallout
Hot or cold surfaces
Abrasion or impact
Protection of surfaces from direct rain washing
Consistent channelling of runoff water across an area of the protected surface
Prevailing winds which transport contamination from one location to another

Unwashed and dirt collecting areas are the first to deteriorate. The only solutions are to either eliminate them by cladding, or frequently wash them down.

Chalking
Formation of fine powder on the surface of the paint film during weathering, which can cause colour fading. Although some degree of chalking is a normal, desirable way for a paint film to wear, excessive film erosion can result from heavy chalking.

Peeling
Peeling
Loss of paint due to poor adhesion. Where there is a primer and topcoat, or multiple coats of paint, peeling may involve some or all of the coats.

Alligatoring (also called crocodiling)
Patterned cracking in the surface of the paint film resembling the regular scales of an alligator.

Blistering
Bubbles resulting from localised loss of adhesion and lifting of the paint film from the underlying surface.

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