Expert Witness Journal Issue 67 June/July 2026 - Flipbook - Page 117
The role and impact of polysaccharides
in plaster on the colonisation of
Stachybotrys Chartarum in buildings.
by Dr Aaran Marriner-Clark & Mr Kieran R. McColl.
•
Introduction
Gypsum plaster is a widely used construction
material, valued for its smooth 昀椀nish, 昀椀re
resistance, and ease of application. Traditionally,
gypsum plaster consists mainly of calcium sulphate
hemihydrate, but modern formulations often
include various additives to enhance performance.
One such group of additives is polysaccharides,
which are complex carbohydrates composed of long
chains of monosaccharide units.
Common Types of Polysaccharides Used
Cellulose Derivatives: Methyl cellulose and
hydroxyethyl cellulose are often used for their
thickening and water-retaining properties.
Starch and Dextrin: These provide both water
retention and improved workability.
Gums (e.g., Xanthan, Guar): Used to enhance
viscosity and stability, especially in ready-mix
plasters.
What are Polysaccharides?
Polysaccharides are naturally occurring or
synthetically produced polymers, including
substances such as cellulose, starch, dextrin,
xanthan gum, and guar gum. They are known for
their ability to modify the physical properties of
materials due to their high molecular weight and
ability to interact with water.
Environmental and Health Considerations
Polysaccharides are generally considered safe and
biodegradable, making them environmentally
friendly additives. Their use can reduce the need
for synthetic chemicals in plaster formulations,
contributing to more sustainable building practices.
Functions of Polysaccharides in Gypsum Plaster
•
Water Retention: Polysaccharides improve the
water-holding capacity of plaster. This slows the
rate of water evaporation, allowing for better
curing and reducing the risk of cracks.
•
Workability:
By
increasing
viscosity,
polysaccharides make plaster easier to mix and
apply, providing a smoother 昀椀nish and improved
spreadability.
•
Setting Time Adjustment: Some polysaccharides
can regulate the setting time of gypsum plaster,
allowing for longer working periods or faster
setting, depending on the requirements.
•
Conclusion
The incorporation of polysaccharides into gypsum
plaster
formulations
signi昀椀cantly
improves
performance by enhancing water retention,
workability, adhesion, and durability. These natural
or semi-synthetic additives are a key component in
modern construction materials, supporting both
technical and environmental advancements.
Polysaccharides in Paint: Functions
and Bene昀椀ts
Improved Adhesion: Certain polysaccharides
enhance the adhesive properties of the plaster,
ensuring better bonding to surfaces such as
brick, concrete, or wood.
EXPERT WITNESS JOURNAL
Reduction of Shrinkage: By controlling water
loss and setting characteristics, polysaccharides
help minimise shrinkage, which can prevent
cracking and increase the durability of plastered
surfaces.
Polysaccharides are complex carbohydrates, often
derived from natural sources, and are increasingly
used as additives in modern paint formulations.
Their inclusion is driven by both performance and
sustainability goals.
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JUNE 2026
