Term: poor alkali resistance

Poor alkali resistance refers to a material's or coating's inability to withstand alkaline (high pH) substances, such as those commonly found in cement, concrete, lime, or plaster. In the context of painting and coatings—especially in the construction and painting industries—this term is often used to describe paint or surface coatings that degrade, discolour, or lose adhesion when applied to or exposed to alkaline surfaces.

In practical terms (especially in Australia’s painting industry):

• Alkaline surfaces include fresh concrete, cement render, brickwork, and mortar.
• If a paint has poor alkali resistance, applying it directly onto these surfaces (especially when not fully cured) can lead to:
  • Efflorescence (white, powdery deposits)
  • Peeling or blistering
  • Discolouration or fading
  • Loss of adhesion

Common causes:

• Applying paint too soon on new masonry or concrete (before full curing)
• Using the wrong type of paint (e.g., oil-based or low-quality acrylics) on alkaline substrates
• Lack of proper surface preparation or priming

Best practice:

To avoid issues related to poor alkali resistance, professional painters in Australia typically:

• Allow masonry surfaces to cure for at least 28 days
• Use alkali-resistant primers before applying topcoats
• Choose high-quality acrylic paints designed for masonry

Summary:

Poor alkali resistance means the paint or coating is vulnerable to damage when exposed to alkaline materials, leading to premature failure of the finish.