Working together through a white hot issue for painters
With the use of white set plaster continuing to grow in Western Australia, so too are the number of complaints to the Building Commission by consumers concerned about paint peeling off damaged areas of plaster. Increasingly, the issue is being found to be with the plaster rather than the painting work. A working group has been formed to tackle this industry-wide problem.
Convened by the Master Painters and Decorators Australia (MPDA) and with representation from the WA Building Commission and other key painting, building and plastering industry stakeholders, the White Set Plaster Working Party will meet regularly to address issues with painting over this type of substrate.
Senior Painting Inspector David Anderson is one of two Building Commission representatives in the working party and says the issues of concern may stem from inconsistency of the mix, the incorrect preparation or application of the plaster or not being given the sufficient time to manipulate the set to a hard and durable finish.
“The application of white set plaster requires careful planning and preparation to achieve the desired quality finish,” Mr Anderson said.
“This is due to the variable and inconsistent nature of the substrate, its softness and its relatively low cohesive strength.
“We are finding that often what comes to us as a complaint about painting work may in fact be an issue with the plaster. Unfortunately, issues with the plaster often don’t become evident until after the surface is painted.”
MPDA President Alan Walters said the association was looking at ways to identify any issues with the plaster before the paint is applied.
“We are undertaking a trial that is designed to provide a means to identify a potentially faulty plaster substrate, as well as a measure of a satisfactory Industry standard of finish,” Mr Walters said. “We will be publishing the results on completion of the samples and testing.”
The plastering industry strongly advocates standards for the mixing and application of plaster products and is represented in the working party by the Master Plasterers Association and the WA Solid Plasterers Association.
The Housing Industry Association, PPG Paints, Valspar Paints, Dulux Paints, Independent Industrial Chemist, Lime Industries and CSR are also involved, along with a Senior Technical Officer from the Building Commission, who is investigating the issue from a building perspective.
The investigation is being undertaken with a view to educating builders, plasterers, painters and the wider industry on a best practice approach.
Six plaster facts for painters
- Plaster is not a natural product; set plaster is derived from a mixture of chemically reactive ingredients and each batch mixed can vary depending on the individual applicator or plasterer.
- The composition of the plaster can vary depending on the depth of the plaster and also across the surface of each layer within the setting.
- There are generally two types of binders used in set plaster; gypsum (calcium sulphate) and lime (calcium hydroxide). Each requires different application properties to the set plaster, including setting time, workability and surface hardness.
- Due to Western Australia’s varying climate, additives are often used in the mix to improve the application properties. The properties of set plaster used in winter will be dramatically different to that used in summer.
- The conditions that may require attention prior to painting include residual moisture, alkalinity, efflorescence, soundness (cohesion) and evenness of the surface (roughness or cracking).
- The recommended preparation and painting systems for application to white set plaster is published in the Australian Standard AS/NZS 2311:2009.
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