It is not unusual to hear that anywhere from 75% to 95% of all coating failures are caused by surface preparation and application errors. One might suspect that these percentages are influenced by for example who made the statistic (paint manufacturer, contractor, owner, etc.), where the failures were observed (climatic conditions, expectations, etc.), any industry association (offshore, marine, architectural, construction / production, etc.), and when the data were collected (technology and standards are developing).

A study of paint failures carried out over many years in Australia in 1993 and updated in 2000 after additional investigations concluded that:

Paint failures can be classified in various ways, for example stages: 1) in tin, 2) during application, 3) during curing, 4) during service life.

They can also be divided into failures caused by weather and corrosion, mechanically induced failures, adhesion and blistering failures, chemically induced failures, light and radiation failures, heat induced failures, and biologically induced degradation and failures.

In this course we will restrict ourselves to the most common types of paint and coating failures:

Wet film failures

• Sagging, curtain, runs
• Dry spray/over spray
• Fish eyes

Dry film failures

• Holiday, low film thickness
• Orange peel
• Pin hole
• Popping
• Wrinkle/lifting
• Sweating and carbonation
• Blooming/blushing
• Osmotic blistering
• Pin point rust
• Cracking
• Delamination
• Chalking
• Bleeding
• Vacuoles

How to describe difference of various defects?

Identification of a defect can be based on cause, appearance and stage of service life. However, a drawing can be an easier way:

When do paint defects occur?

• Paint defects can occur at any time when paint is used
• Defects usually occur during one of two stages
  • During application (incl. curing/drying)
  • During service
• Some defects may only occur during application, such as sagging and fish eyes
• Some defects are prone to appear during exposure, such as cracking, delamination and blistering

What will cause paint defects?

• Inadequate (blast) cleaning and surface profile is a frequent cause of paint defects
• Poorly operated and maintained equipment, wrong application technique and poor planning will all increase the risk of paint defects
• All paint and coating systems are designed for specific use and exposure. Wrong specification may cause paint defects
• Sometimes paint defects are due to a combination of unfortunate circumstances related to surface preparation, application and exposure