MAX DUO 2-in-1 universal mounting foam (gun + straw)

MAX DUO 2-in-1 mounting foam by Lacrysil is a one-component polyurethane foam that can be applied with a foam gun or with the applicator straw supplied with the can. Use it to fit windows and doors, fill gaps and voids, and insulate joints against heat loss and noise.

Two ways to apply, two different foams

The application method changes how the foam behaves in the joint, not just how easy it is to use:

• With a gun: up to 70 l yield, 50–100 % volume increase. The bead gains initial stability faster and barely grows afterwards, so it does not push frames out of shape. Use this for windows and doors. Fill the joint to 2/3.
• With the straw: up to 35 l yield, 400–700 % volume increase. The structure is denser and the foam expands strongly to fill irregular and large horizontal voids. Fill the joint to 1/3. It can deform delicate parts, so it is not suitable for window frames.

You do not need to buy a gun: the straw is enough for a one-off job, and for a run of windows the can goes on a gun.

All-season: -10 to +35 °C

Apply at an air temperature of -10 to +35 °C and relative humidity of at least 70 %. Keep the can at +18…+30 °C for 24 hours before use; during application it should be at +15…+30 °C. A cold can gives less yield and a coarser structure. Cured foam works from -60 to +100 °C and resists moisture and weathering.

Curing times

Tack-free in 5–30 minutes. Curing: 0.5–12 hours with a gun, 1–12 hours with the straw. Full polymerization: 12–24 hours with a gun, 24–48 hours with the straw. Exact values depend on can temperature and humidity.

How to apply

1. Clean the joint of dust, grease, ice and frost. Above freezing, moisten the surfaces.
2. Shake the can for at least 1 minute, remove the cap, attach the gun or the straw.
3. Hold the can upside down and fill from the bottom up: to 2/3 with a gun, to 1/3 with the straw.
4. Fill joints deeper than 4 cm and wider than 6 cm in layers. Apply each layer once the previous one is tack-free, moistening it first.
5. Trim cured excess and paint or plaster over the joint.

Limits

The foam does not withstand UV, so always cover the joint. Remove fresh foam from surfaces and the gun with Lacrysil foam cleaner, keeping the cleaner off polystyrene. Cured foam comes off mechanically only. The product contains isocyanates: wear gloves and goggles and ventilate indoor spaces.

Packaging and storage

850 ml can (1000 g gross), beige foam. Store valve up at +5…+30 °C, do not heat above +50 °C. Shelf life 18 months.

FAQ

How is MAX DUO different from regular household foam? Household foam is applied only with a straw. MAX DUO works with both, and with a gun it gives twice the yield with almost no post-expansion.

How many cans do I need per window? One can on a gun is usually enough for a standard 1.3×1.4 m window with a 2 cm joint. Wide or uneven joints take more.

Why is the yield below 70 l? 70 l is achieved with a gun and a can warmed to room temperature. In the cold or with the straw the yield is lower; expect about 35 l with the straw.

When can I trim the excess? Once cured: roughly 0.5–12 hours with a gun, 1–12 hours with the straw, depending on temperature.