Soudal Silirub LMN is a premium low modulus neutral cure silicone sealant for UPVC glazing, windows, and facades. Available in clear, white, black, and anthracite. Flexible, durable, and non-corrosive. Suitable for movement joints and sensitive substrates.
Colour
Price
QTY
Black
£2.98£3.58
Anthracite
£2.98£3.58
White
£2.98£3.58
Clear
£2.98£3.58
Soudal Silirub LMN is a premium low modulus neutral cure silicone designed specifically for glazing, UPVC window systems, curtain walling, and facade sealing. Low modulus means the cured sealant remains highly flexible under stress, absorbing joint movement without tearing away from the substrate. Because it cures by neutral chemistry rather than acetic acid, Silirub LMN will not corrode metal fixings, damage coatings, or irritate sensitive surfaces. For anyone who has had an acetoxy silicone blush a polished aluminium frame or eat into a mirror backing, the difference is immediately obvious.
Silirub LMN is available in four colours: clear, white, black, and anthracite. The anthracite shade is particularly useful on grey UPVC and aluminium systems that have become standard across modern window installations. Colour consistency is reliable batch to batch, which matters when you are resealing a run of windows and need the joints to match.
Where Soudal Silirub LMN Low Modulus Silicone Gets Used
This is a product that earns its place on glazing jobs, window installations, conservatories, and curtain walling. The neutral cure formula makes it safe to use directly against coated aluminium, anodised profiles, structural silicone systems, and mirror-backed glass without risking chemical damage. Window fitters, glaziers, and facade contractors use Silirub LMN as a reliable day-to-day sealant for perimeter glazing, weathersealing around frames, and sealing the joint between window frames and masonry or render.
The low modulus characteristic is what separates this from a standard silicone. Standard high modulus silicone is stiffer when cured and transfers stress directly to the bond line. On movement joints, or anywhere a substrate expands and contracts with temperature, that stress causes adhesion failure over time. A low modulus silicone stretches with the joint rather than fighting it, which is why it is specified on glazing systems, composite panels, and facade elements where thermal movement is a real factor.
Compatibility on Sensitive Substrates
Silirub LMN bonds well to glass, UPVC, coated and uncoated aluminium, powder-coated steel, and most painted or primed masonry surfaces. Because the curing mechanism releases alcohol rather than acetic acid, there is no vinegar smell during application and no risk of acid attack on the substrates around the joint. This makes it the sensible choice anywhere an acetoxy silicone would be inappropriate, including against natural stone, certain adhesives, and electrical components near window or facade joints.
The 310ml cartridge is the standard size for most sealant guns on site. At this price point, Silirub LMN offers genuine quality at a trade-friendly rate. If you are working through volume on a window contract or a multi-unit project, it is worth speaking to us about quantity pricing, as the savings on a full box order add up quickly.
Pro Tip: On deep glazing rebates, tool the joint within five minutes of application before a skin forms on the surface, as Silirub LMN skins faster in warm weather and a poorly tooled joint on a visible frame is a difficult conversation with a client.
Soudal Silirub LMN is used across glazing and fenestration work wherever a flexible, non-corrosive seal is needed. Window fitters use it to seal UPVC and aluminium frames to masonry, glaziers apply it around glass units in curtain walling, and facade contractors rely on it for movement joints on composite cladding panels. It is also used in conservatory construction, structural glazing systems, and anywhere acetoxy silicone would damage the surrounding materials. The neutral cure formula makes it safe against a wide range of coatings, metals, and stone surfaces.
Best For
UPVC window frame sealing
Aluminium and coated metal glazing systems
Curtain walling and facade joints
Conservatory construction
Movement joints with thermal expansion
Mirror and reflective glass backing
Compatible Surfaces
Glass
UPVC
Anodised and powder-coated aluminium
Painted and primed steel
Natural stone and masonry
Coated and laminated panels
Key Properties
Low modulus neutral cure formula
No acetic acid release during curing
High flexibility in cured state
Resistant to UV and weathering
Available in clear, white, black, anthracite
310ml standard cartridge
Not suitable for: Silirub LMN is not suitable for structural load-bearing glazing applications where a structural silicone is specified. It is not recommended for use on polyethylene, polypropylene, or PTFE surfaces, as silicone does not bond reliably to these materials without specialist primers.
Clean both surfaces thoroughly before applying Soudal Silirub LMN. Remove any old sealant, dust, grease, or release agents. On non-porous surfaces such as glass or aluminium, a solvent wipe with isopropanol or acetone followed by a dry cloth will give the best adhesion. Allow the solvent to evaporate fully before applying the silicone.
Cut the cartridge nozzle to the joint width required and load into a standard sealant gun. Apply the sealant in a single continuous bead, filling the joint completely. Tool within five minutes to ensure full contact with both faces of the joint. Silirub LMN will skin within approximately 20 to 30 minutes at 20 degrees Celsius and reach full cure in 24 to 48 hours depending on joint depth, temperature, and humidity.
Remove all traces of old sealant, dirt, grease, and surface coatings from both joint faces
Wipe non-porous surfaces with isopropanol or acetone and allow to dry completely before applying
Apply masking tape either side of the joint if a clean finish line is required
Cut the cartridge nozzle at a 45-degree angle to match the joint width
Load the cartridge into a standard 310ml sealant gun
Apply a continuous, even bead of Silirub LMN along the full length of the joint
Tool the sealant firmly within five minutes to ensure full adhesion to both surfaces
Remove masking tape before the sealant skins over
Allow full cure of 24 to 48 hours before exposure to water or sustained movement
What is the difference between low modulus and standard silicone sealant?
Low modulus silicone, like Soudal Silirub LMN, remains highly flexible once cured and can stretch considerably without losing adhesion. Standard or high modulus silicone cures to a stiffer consistency and transfers more stress to the bond line when a joint moves. For glazing and facade applications where thermal expansion causes regular joint movement, low modulus silicone is the better choice as it absorbs that movement rather than fighting it.
Why does neutral cure silicone matter for UPVC and aluminium frames?
Acetoxy silicones release acetic acid as they cure, which can corrode metal fixings, damage coatings on aluminium profiles, and cause staining on certain stone and masonry surfaces. Neutral cure silicones like Silirub LMN release alcohol instead, so there is no corrosive by-product. This makes Silirub LMN safe to use directly against anodised and powder-coated aluminium, coated steel, and sensitive substrates where an acetoxy product would cause damage.
Can Soudal Silirub LMN be used on external joints exposed to the weather?
Yes. Silirub LMN is formulated for exterior use and has good resistance to UV exposure, rain, and temperature cycling. It is regularly used on perimeter window seals, curtain walling joints, and facade panels where long-term weathering performance is required. The cured sealant will not chalk or crack under normal outdoor conditions.
Soudal Silirub LMN is a one-component, low modulus, neutral cure silicone sealant based on polydimethylsiloxane chemistry. Curing occurs by moisture exposure at room temperature, releasing alcohol rather than acetic acid. The cured product provides a permanently flexible seal with good adhesion to glass, UPVC, coated metals, and masonry. Silirub LMN carries CE marking for use in construction joints under relevant European standards for sealants in facade and glazing applications.
From £38.16£45.79 EX VATINC VAT Select options This product has multiple variants. The options may be chosen on the product page
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