Joint Sealants — PU, Polysulphide, Silicone & Hybrid MS
Joint sealants supplier for Delhi NCR: single-component polyurethanes, two-part polysulphides, neutral-cure silicones, hybrid MS polymers and fire-rated grades from Fosroc, Sika, Soudal, Dr. Fixit and STP — selected by movement class, not by whatever is on the shelf.
Sealants Fail By Selection, Not By Brand.
A joint that keeps splitting was almost always filled with the wrong chemistry, the wrong modulus, or no backer rod at all.
Every sealant family has a job: polysulphide for trafficked and water-retaining joints, low-modulus PU for wide building joints, hybrids for façades that must be painted, silicone for glazing and wet areas. We stock all of them — with the primers and backer rods that make the datasheet numbers real — and our crews re-seal failed joints across NCR.
Five Sealant Families We Stock.
1. Single-component polyurethane (PU)
Non-shrink, ready to use straight from the cartridge — no mixing. Service temperature −40°C to +90°C, surface-dry in 24 hours, full cure in up to 7 days, shelf life 12–18 months unopened. The workhorse for expansion joints, façades, window and door frames, industrial floors and roofing details.
2. Two-component polysulphide
The classic Indian spec for heavily-trafficked floor joints, civil structures and water-retaining structures — excellent chemical resistance and a service life that often exceeds 20 years. Gun grade for vertical work, pouring grade for floors; cures in 24–48 hours. For runways and rigid pavements we also supply Fosroc’s cold-applied, fuel-resistant Colpor 200PF.
3. Hybrid MS polymer
Silyl-modified polymer sealant-adhesives: isocyanate- and solvent-free, primerless adhesion on most substrates, paintable, fast strength build-up. The modern replacement for PU on façades, cladding and interior bond-and-seal work.
4. Silicones
Neutral-cure building and glazing silicones with excellent UV resistance for weatherseal joints, curtain walls, sanitary and wet areas — including RAL colour-matched grades for architectural work.
5. Fire-rated sealants
Fire-resistant acrylic and PU grades for joints and penetrations in fire-rated walls and floors, specified alongside fire barriers in joint assemblies.
Match The Sealant To The Joint.
| Joint type | Sealant family | Example products |
|---|---|---|
| Trafficked floor joints — warehouses, car parks | 2K polysulphide / PU, pouring grade | Thioflex 600 PG · ShaliSeal PU PG 2K · Sikaflex PRO-3 |
| Building expansion joints, wide movement | Low-modulus 1K PU | Soudaflex 20LM · Sikaflex Construction+ |
| Façade & cladding panel joints (paintable) | Hybrid MS polymer | Nitoseal MS600 · Fix ALL Flexi |
| Water-retaining structures — tanks, STPs | 2K polysulphide | Thioflex 600 · ShaliSeal PS PG |
| Runways & rigid pavements | Cold-applied, fuel-resistant grade | Colpor 200PF |
| Glazing, sanitary & wet areas | Neutral-cure silicone | Sikasil · Silirub 989 |
| Fire-rated joints & penetrations | FR acrylic / FR PU | Firecryl FR · Soudaflex FR |
Failed Joints, Re-Sealed Properly.
Our crews cut out failed sealant, re-prepare the joint, set the backer rod and re-seal with polysulphide or PU — the full procedure, not a cosmetic top-up.
Frequently Asked.
Which sealant should I use for an expansion joint that keeps failing?
First find out why it failed — usually wrong modulus, three-sided adhesion (no backer rod), or no primer. For most building expansion joints we specify a low-modulus 1K PU like Soudaflex 20LM over a backer rod; for trafficked floors, a pouring-grade polysulphide like Thioflex 600 PG. Send joint photos and width on WhatsApp for a firm recommendation.
PU or polysulphide — what is the difference?
Polyurethane offers strong adhesion, tear resistance and is paintable; polysulphide offers superior chemical resistance and a service life often exceeding 20 years, which is why it remains the spec for water-retaining structures and heavily-trafficked joints. Polysulphide is two-component and machine-mixed; most PUs are single-component and gun-ready.
How long does a PU sealant take to cure?
Typically surface-dry in 24 hours and fully cured in up to 7 days, depending on joint depth, temperature and humidity. Two-component polysulphides generally cure in 24–48 hours. Keep the joint free of movement and water until cure is complete.
Do I really need a backer rod and primer?
Yes. The backer rod controls sealant depth, cuts consumption and prevents three-sided adhesion so the sealant can stretch; the primer secures the bond on porous or dusty substrates. Skipping either is the fastest route to a failed joint — see backer rods.
What shelf life do sealants have, and how should they be stored?
Unopened 1K PU cartridges last 12–18 months; one-component polysulphides around 12 months stored at 4–27°C; two-component polysulphides between 6 and 24 months by grade. Store cool, dry, out of direct sunlight and in original unopened packaging.