About STP ShaliSeal PU GG

STP ShaliSeal PU GG is a single-component, moisture-curing polyurethane sealant built for the everyday movement joints that run through almost every building and infrastructure project. Straight from the sausage it is a grey, non-sag thixotropic paste, so it holds its shape in vertical and overhead joints without slumping. Once gunned into place it reacts with humidity in the air and cures, over a few days, into a flexible elastomeric rubber that grips the joint faces and moves with them. For engineers and applicators in India, the appeal is simplicity: no two-part mixing, no pot-life race against the clock, and a chemistry that works comfortably in our warm, humid site conditions.

Where the product earns its keep is durability under real exposure. The cured seal handles a service range of roughly -30 to +80 degrees C, shrugs off UV and weathering without cracking, and stands up to dilute acids, alkalis and fuels, which is why the same material is trusted in swimming pools and chemically treated water as well as on external facades. With a movement accommodation factor of plus or minus 25 percent, it absorbs the routine thermal and structural cycling that opens and closes an expansion joint season after season. It is a general-purpose workhorse rather than a specialist trafficked-deck or fuel-immersion sealant, and specified correctly it gives long, low-maintenance joint life across a broad spread of building and civil applications.

The technical insight

The performance comes from moisture-cure polyurethane chemistry. The sealant leaves the pack as a stable, isocyanate-terminated prepolymer that reacts with water vapour from the surrounding air; that reaction cross-links the polymer into a three-dimensional elastomer, curing at roughly 3 mm per 24 hours from the surface inward at 30 degrees C and 55 percent RH. Because the cure depends on ambient humidity, it slows markedly in cold or very dry conditions, which is why STP caps application at substrates and air above +10 degrees C. The cured rubber reaches over 600 percent elongation with a low Shore A hardness of 20 to 25, giving it the soft, high-strain character a movement joint needs: it stretches and recovers rather than tearing or debonding as the joint width cycles. Correct joint design is what unlocks that ±25 percent rating in practice. A closed-cell polyethylene backer rod sets the sealant depth and, critically, prevents three-sided adhesion so the bead can flex freely between only its two side faces. On porous edges a compatible primer builds the adhesion that lets the seal move under load instead of peeling. Get the width-to-depth ratio, backer rod and priming right and the material delivers its rated movement; skip them and even a good sealant fails early at the bond line.

Where it is used

• Vertical and horizontal expansion and movement joints in concrete structures
• Building facades, curtain walls, panel walls and parapet joints
• External wall and cladding joints in metal and panelised structures
• Perimeter sealing around aluminium, PVC, timber and metal door and window frames
• Precast and tilt-up element joints
• Roads, airport runways and taxiway joints
• Sealing joints in swimming pools and chemically treated water tanks
• Sanitary and general building joints requiring a flexible, paintable seal

Key advantages

• Single component and ready to gun, so no site mixing, no pot life and less wastage
• Accommodates ±25% joint movement (IRC-57-2006) for durable, flexible seals
• Bonds well to concrete, glass, stone, wood and anodised aluminium, often with a primer
• Excellent UV and weather resistance with no cracking under accelerated weathering
• Resists dilute acids, alkalis and fuels, suiting pools and chemically treated water
• Non-sag thixotropic paste holds its shape in vertical and overhead joints
• Paintable once tack-free, letting the joint blend into finished surfaces
• Conforms to BS 5212, ASTM C 920 and EN 14187-5 for specification confidence

Limitations & considerations

• Cure is moisture and temperature dependent and slows sharply in cold, dry weather; do not apply below +5°C or on frozen or wet surfaces
• Movement rating is limited to ±25%, so joints with higher design movement need a higher-class sealant
• Contains isocyanate and requires gloves, goggles and adequate ventilation during use
• Cannot be applied over silicone, or alongside curing silicone or hybrid sealants, without adhesion failure
• Supplied only in 600 ml sausages in grey, so large-volume or colour-matched work needs planning
• Once opened, a sausage should be used within 24 hours or the sealant may harden inside the pack

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliSeal PU GG

STP ShaliSeal PU GG sits in the general-purpose polyurethane end of the joint-sealant range and pairs naturally with its required primers, ShaliPrime S and ShaliPrime PUM, which we supply alongside it. Where a specifier prefers a two-part pouring-grade PU for wide horizontal or trafficked joints, STP’s ShaliSeal PU PG 2K is the companion within the same brand family. For projects standardised on other brands, comparable single-component options include Fosroc Nitoseal PU40 (one-part gun-grade PU) and Fosroc Nitoseal MS600 (an MS-polymer joint sealant), while Sika’s Sikaflex range covers similar facade and expansion-joint duties. As an authorised distributor and applicator across Delhi NCR and Pan-India, Space Arc can help match the right sealant, primer and backer rod to your joint design rather than defaulting to a single product.

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