Roundtower Chalk Dust is a finely crushed, screened off-white powder, widely used as a filler and pigment extender in a variety of traditional and conservation-grade applications. With a consistent particle size of approximately 7 microns, a slightly alkaline pH in water, and a loose bulk density of 0.92 kg/L, this high-purity chalk is ideal for use in lime-based plasters, mortars, paints, and roofing treatments.
✔️ Fine Particle Size: ~7 microns for smooth integration into mixes
✔️ Colour: Consistent off-white, dull matte finish
✔️ pH: Slightly alkaline when mixed with water
✔️ Bulk Density: 0.92 kg/L (loose)
✔️ Packaging: 25kg paper sack
Applications
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Filler in lime plasters and mortars to improve texture and finish
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Roofing: Painted onto lead flashing with a binder to prevent underside corrosion
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Pigment extender in traditional limewash and breathable mineral paints
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Surface finishing in decorative and protective conservation coatings
Key Benefits
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Crushed and screened for consistent grading and colour
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Compatible with lime, casein, or other traditional binders
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Suitable for use in heritage conservation, restoration, and sustainable construction
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Provides reliable bulk and opacity in custom limewash or filler formulations
