Ready-mixed natural hydraulic lime (NHL) mortar for exposed freshwater and saltwater environments above the waterline.
Refined, natural buff finish. Supplied in 25 kg polythene-lined paper bags (batch and colour coded). FIBC (1-tonne) bags available.
Part of the Cornerstone Marine range, Marine L4 is the lowest-strength, slowest-setting formulation in the family—chosen when maximum vapour permeability, capillary activity and substrate compatibility are the priority, and a rapid set is not required.
Why choose Marine L4 (when to specify)
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Breathable & capillary-active: Promotes drying in marine, riverside and estuarine masonry above the waterline.
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Gentle binder strength: Better matches softer historic stones and bricks; reduces risk of edge damage and future incompatibility.
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No Portland cement: Suited to conservation, renovation and projects that require cement-free mortars.
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Longer open time: Undemanding to place and finish on complex profiles and deep joints.
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Refined buff finish: Natural, pigment-free colour that sits well on heritage fabric.
Use L4 for pointing and bedding in splash-zone / spray-zone conditions with minimal tidal washout risk.
Switch to Marine LP6 where faster setting is necessary or submerged/immersion exposure is expected.
Typical applications (above water level)
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Harbour and quay parapets, capping stones and copings
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River and canal walls, bridge parapets, lock surrounds (non-immersed zones)
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Sea-front elevations, piers and revetments in the splash/spray zone
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General repointing and bedding of water-bearing masonry where breathability is required
Key technical characteristics
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Binder: Natural Hydraulic Lime with selected natural sands (no pigments).
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Permeability: Designed for high vapour permeability and capillary activity.
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Setting time: ≈ 8 hours at 17 °C (ambient conditions govern set).
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Working/open time: Extended; varies with temperature, wind and substrate suction.
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Colour: Natural buff; final tone is influenced by curing and site conditions.
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Strength class within range: Lowest strength in the Marine series (chosen for compatibility and breathability).
Coverage & yield
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25 kg bag → Approx 14.5 litres of fresh mortar.
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Fills approx 1.5 m² of joint at 10 mm depth (actual yield depends on joint width/depth and substrate texture).
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Recommendation: Conduct on-site trials to confirm project-specific consumption.
