Impermax Polyurea H Flex Alum: Aluminium Polyurea Roof Coating, No Topcoat
Impermax Polyurea H Flex Alum is a two-component polyurea resin that cures very fast into a flexible membrane with excellent crack-bridging. Hot-sprayed with plural-component equipment, it is an aluminium polyurea roof coating that keeps its colour without a topcoat.
- Product: Impermax Polyurea H Flex Alum
- Application: hot-spray waterproofing
- Mix: A=1 : B=1.08 by weight / 1:1 by volume
- Gel time: 8–9 s at 25 °C
- Colour: aluminium
The metallic, aluminium-coloured version of Impermax Polyurea H Flex, with the same certificates; mechanical values below are those listed on the Alum datasheet.
01 · Uses
Uses of an aluminium polyurea roof coating
- Protection and waterproofing of exterior structures, especially roofs and terraces.
- Projects that need a colour-stable aesthetic finish.
- Saving one step in the system by doing without the aliphatic topcoat.
Encapsulating spray foam? See Rayston foam encapsulated with Impermax Polyurea H Flex Alum and the spray polyurethane foam guide.
02 · Application
How Impermax Polyurea H Flex Alum is applied
It is sprayed with hot plural-component equipment; a compressed-air dryer (refrigeration dryer) or compressed-air drying filters are recommended. Concrete is prepared mechanically by high-pressure blasting or scarifying to remove laitance and open the pores, then primed and levelled to a regular surface; dust and loose particles are removed by brushing or vacuum.
The substrate must be flat and cohesive, with a pull-off strength of at least 1.4 N/mm², free of cracks, clean and dry. Stir component A until the pigment is homogeneous before loading – but do not overmix, as that increases moisture uptake – then recirculate both components while heating to application temperature.
The required thickness is usually reached in one coat; a second coat can follow straight away if needed, and cleaning the previous coat with xylene is recommended for good adhesion. Wind above 25 km/h can cause excessive heat loss and affect gun mixing, surface texture, cure and physical properties.
Technical datasheet: Impermax Polyurea H Flex Alum TDS (PDF) · Polyurea waterproofing systems
03 · Technical data
Impermax Polyurea H Flex Alum technical data (TDS values)
Elongation at break
400%
Tensile strength
14 MPa
Shore hardness
90A/40D
Tear strength
69 N/mm
Technical data
- Hardness (Shore): 90A/40D (ISO 868)
- Elongation at break: 400%
- Tensile strength: 14 MPa (EN-ISO 527-3)
- Tear strength: 69 N/mm (ISO 34-1, method B)
- Adhesion: 5.6 MPa on concrete (EP 100 primer); 3.6 MPa on steel (PU primer)
- Electrical resistance: 3.55 × 10⁹ Ω (EN 1081:2019, method A, vertical resistance)
- Surface resistivity: 1.60 × 10¹³ Ω/sq (ASTM D257-14)
- Volume resistivity: 6.80 × 10¹² Ω·cm (ASTM D257-14)
- Chemical resistance (7 days permanent contact at 80 °C; 0 worst, 5 best): water 5, ammonia (3%) 5, HCl 3M (9%) 4, isopropyl alcohol 1, xylene 0, sulphuric acid (50%) 0
Approvals
- Fire test DIN 4102-1:1998 (flammability under direct flame): Class B2
- ETA 21/0740 (EAD 030675-00-0107) with CE marking
04 · Performance
What makes the Alum version different
Two things set it apart from the other colours: improved electrical conductivity (an antistatic effect), and a special colour that does not turn yellow in sunlight – so it needs no aliphatic topcoat to keep its colour and appearance.
Under usual conditions (25 °C, 50% RH) the membrane resists rain after 15 minutes, takes light foot traffic after 1 hour, and reaches 90% of its final properties after 2 days.
Application data
- Mix ratio: A=1, B=1.08 by weight; A=1, B=1 by volume
- Gel time (A+B, 20 g): 8–9 s at 25 °C, 4–6 s at 60 °C
- Recommended temperatures: component A 70 °C, component B 70 °C, hose 65 °C
- Spray pressure: at least 135–170 bar
- Reference spray rate: 2 kg/m²
- Air temperature: 10–40 °C, relative humidity below 85%
- Shore A/D build-up (1 mm, 25 °C, 50% RH): 74/27 after 10 min, 77/29 after 20 min, 80/30 after 1 h, 88/35 after 24 h
- Storage: 10–30 °C, dry; use within 12 months of manufacture in the sealed container
05 · FAQ
Impermax Polyurea H Flex Alum: frequently asked questions
Does Impermax Polyurea H Flex Alum need a UV topcoat?
No. Its special aluminium colour does not yellow in sunlight, so no aliphatic topcoat is needed to keep the colour and appearance.
Is it antistatic?
It has improved electrical conductivity (antistatic effect) compared with the other colours; the datasheet gives 3.55 × 10⁹ Ω vertical resistance to EN 1081.
How does it relate to Impermax Polyurea H Flex?
It is the metallic version with the same certificates, including ETA 21/0740; use the mechanical values from the Alum datasheet.
More Impermax and Rayston polyurea products
Every product page in this series is based on its official Krypton Chemical technical datasheet.
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