Finishing paint PASSIVE PURPLE BRUSH

liquidfor wallviolet

Product overview
Passive Purple Brush is a fibre‑reinforced, brush‑applied, liquid airtight membrane designed for detail sealing and small‑scale airtightness works. It creates a continuous vapour‑control, airtight and smoke‑tight layer suitable for junctions, penetrations and repairs where spray or roller application is impractical.

What it is and how it works
Applied to the warm side of insulation, the product cures to form a seamless barrier that prevents unintended air leakage through walls, floors, roofs and junctions. The fibre reinforcement aids bridging of cracks and gaps up to 5 mm and improves handling in precision applications.

Application methods

• Brush application (Passive Purple Brush) — flat brush recommended for junctions, service penetrations and detail work.
• Part of the Passive Purple family — spray and roller variants exist for larger surfaces; select the brush version for detailed sealing and repairs.

Suitable uses & substrates

• Service penetrations (pipes, cables, ducts), window and door frames, floor‑to‑wall and wall‑to‑ceiling junctions.
• Substrates: brick, block, concrete, timber, plasterboard, OSB and steel.
• Suitable for new build, retrofit and Passivhaus projects where continuity of the airtight layer is required.

Main benefits

• Creates a continuous vapour‑control and airtight layer for precision sealing.
• Fibre reinforcement bridges cracks up to 5 mm for reliable detail work.
• Water‑based, low VOC formulation suitable for indoor use.
• Plasterable, renderable and paintable once cured.

Airtightness, explained

• Definition: control of unintended air leakage through the building fabric.
• How achieved: by creating a continuous airtight barrier; liquid membranes provide continuous coverage without overlaps.
• Performance benchmarks: Passivhaus Class A airtightness 0.02 m³/h·m² @ 50 Pa; typical UK new‑build target ≤10 m³/h·m² @ 50 Pa.

Preparation & priming
Surfaces must be sound, clean, dust‑free and dry. Large gaps (>5 mm) should be pre‑filled with a suitable filler or foam; medium gaps (2–5 mm) can be treated directly. Use recommended primers on very porous or sealed substrates and apply Supergrip primer where plaster or adhesives will be applied over the membrane after curing.

Tested & certified

• Passivhaus Institute Class A airtightness — 0.02 m³/h·m² @ 50 Pa (EN 12114)
• Air barrier material — 0.02 L/s·m² @ 75 Pa (ASTM E2178)
• Reaction to fire: ASTM E84 Class A; EN 13501‑1 Euroclass C‑s1,d0 (B‑s1,d0 with FRED system)
• Vapour control (variable Sd) ~0.8–40 m (EN ISO 12572); watertight (EN 14891)
• Low VOC: French A+ and Finnish M1 emissions ratings (EN 16516 / RTS); Environmental Product Declaration (EN 15804)
• ICC‑ES ESR‑4715, BBA approval and mould resistance (ASTM D3273)

Caractéristiques / technical specifications

• Brand: Intelligent Membranes
• Product name: Passive Purple Brush
• Type: fibre‑reinforced, brush‑applied liquid airtight membrane
• Colour: purple
• Pack sizes (typical): 6.9 kg (selected); 3.7 kg (option)
• Indicative coverage: ~1 kg ≈ 1 m² (depends on application and substrate)
• Bridging: cracks up to 5 mm
• Passivhaus airtightness: 0.02 m³/h·m² @ 50 Pa
• Air barrier (ASTM E2178): 0.02 L/s·m² @ 75 Pa
• Adhesion (EN ISO 4624): steel 2.7 N/mm²; CLT 1.83 N/mm²; gypsum 1.6 N/mm²; brick 1.5 N/mm²
• Elongation / flexibility: ~219–350% (EN 12311‑1)