About Sika SikaTop-107 Seal

SikaTop-107 Seal is Sika’s workhorse cementitious waterproofing slurry, and it has earned its place on Indian sites because it does one job reliably across a wide range of structures. The system arrives as a 25 kg pre-batched set — a white acrylic polymer liquid (Part A) in a 5 kg container and a grey Portland-cement powder blended with selected aggregates and admixtures (Part B) in a 20 kg bag — mixed at 1:4 by weight (Part A : Part B) to a lump-free, brushable consistency, with no site water added so the polymer-to-cement ratio stays identical from batch to batch. The material Sika India supplies today as SikaTop-107 Seal IN (formerly SikaTop Seal-107 IN) is the same product that older trade catalogues and purchase orders list as SikaTop 111 Seal. Once cured it forms a continuous, tightly bonded film that stops water moving through concrete and masonry, yet remains vapour-permeable so the substrate can still breathe. That combination of watertightness and breathability is what makes it suitable for the inside of potable water tanks as well as the outside of a basement wall.

For engineers and applicators the practical appeal is how forgiving it is. Unlike liquid-applied membranes that demand a bone-dry surface, SikaTop-107 Seal is designed to be laid over a damp, saturated surface-dry substrate — a real advantage in monsoon conditions or on freshly cured concrete where waiting for full drying is impractical. It tolerates fine hairline movement, resists moderate hydrostatic pressure from both the positive and negative face, and needs only modest surface preparation compared with sheet or bituminous systems. The result is a coating that is quick to specify, straightforward to apply with a site labour crew, and easy to inspect, which is why it remains a default choice for tank linings and wet-area waterproofing across Delhi NCR and pan-India projects.

The other reason it keeps its place on drinking-water specifications is documentation. The coating holds a CFTRI certificate for repeated contact with water and aqueous foods (per USFDA 175.300) and is certified free from acute lethal toxicity to IS 6582, which is exactly what consultants ask for on potable overhead tanks, sumps and municipal reservoirs. Beyond watertightness it also reduces saltpetre efflorescence and shields the concrete and its reinforcement from carbonation and chloride ingress, so it doubles as a protective coating on structures exposed to damp, groundwater or de-icing salts.

The technical insight

The performance comes from how the acrylic polymer works alongside ordinary cement hydration. As the cement in Part A hydrates and gains strength, the polymer emulsion in Part B coalesces into a continuous film that threads through the pore structure of the hardening matrix. This does two things at once: it dramatically reduces the size and connectivity of capillary pores, which is what physically blocks water transmission, and it introduces enough elasticity into an otherwise brittle cement film to bridge the fine hairline cracks that concrete inevitably develops. The polymer also boosts adhesion, gripping the substrate so tightly that the coating can resist negative-side water pressure trying to push it off the wall — the failure mode that defeats many rigid coatings. Because the film is dense but not fully vapour-tight, trapped moisture can still escape as vapour rather than building pressure behind the coating and causing blistering. In short, the cement gives strength and alkalinity while the acrylic gives flexibility, pore-blocking and bond — and the balance between the two is what separates a polymer-modified slurry from a plain cement paint.

The datasheet numbers show what that balance buys you. The cured film stretches roughly 10 % before breaking (ASTM D412) — enough to accommodate fine, non-moving hairline cracks — while recording essentially zero water penetration under 5 bar of hydrostatic pressure held for 72 hours (BS EN 12390-8), which is why it holds back the standing head inside a full tank and not just rain-driven damp. Adhesion is the other half of the story: a tensile bond of 2.0 N/mm² or more (ASTM D4541) to a properly prepared substrate means the coating fails in the parent concrete rather than peeling at the interface, which is what lets it survive negative-side pressure. Two thin crosswise coats matter for the same reason — the crossing brush directions close the pinholes left by the first pass, and thorough pre-wetting stops thirsty concrete from pulling mixing water out of the film before the cement can hydrate.

Where it is used

• Lining of water storage tanks, overhead tanks and underground sumps, including potable water contact
• Basement walls and rafts, waterproofed from either the positive or negative face
• Sewage and effluent treatment structures needing a protective, watertight skin
• Swimming pools, water features and fountains
• Wet areas — toilets, bathrooms, kitchens and balconies — before tiling
• Retaining walls and lift pits in occupied basements
• Terraces, chajjas and parapet junctions as part of a roof waterproofing system
• Protection of concrete against carbonation and mild chemical attack
• Balconies, sunshades, flat roofs and sunk slabs before screeding or tiling
• RCC gutters, drains, planter boxes and canals
• Sealing fine hairline cracks and filling surface pores or blowholes in concrete
• Protection against chloride ingress and freeze-thaw or de-icing-salt attack

Key advantages

• Bonds to damp, saturated surface-dry concrete — no long drying wait before application
• Watertight yet breathable, so vapour escapes instead of blistering the film
• Slightly flexible, bridging fine hairline shrinkage cracks that rigid coatings cannot
• Works against both positive and negative water pressure
• Certified for potable water contact — CFTRI clearance per USFDA 175.300, and free from acute lethal toxicity per IS 6582
• Effectively zero water penetration at 5 bar for 72 hours (BS EN 12390-8), so it withstands real tank head
• Develops 2.0 N/mm² or higher tensile adhesion (ASTM D4541) even on damp substrates
• Non-corrosive to reinforcement; resists carbonation and chloride penetration
• Over-coatable — can be plastered, screeded or tiled once cured
• Applied by brush, roller or spray with ordinary site labour — minimal specialist plant
• Modest surface preparation compared with membrane or bituminous systems
• Pre-batched 25 kg two-part set needs no site water, removing guesswork on polymer dosage

Limitations & considerations

• Rigid-to-semi-flexible only — it will not bridge live, moving or structural cracks; use an elastomeric membrane for those
• Not a decorative finish; it needs a screed, tiling or topcoat where appearance or foot traffic matters
• Hydrostatic resistance is moderate, so very high heads or continuous ponding need a heavier-duty system
• Full curing is essential before flooding, backfilling or tiling — rushing the cure compromises watertightness
• Correct 1:4 mixing and coat thickness must be controlled on site; adding water, over-thinning or a single thin coat will leak
• Not designed for exposed joints, expansion gaps or areas of significant deflection, which need a dedicated sealant or joint treatment
• Short placing window — pot life is about 40 minutes, so mix only what the crew can lay in that time
• Do not apply in direct sun, strong wind or below +10 °C substrate and ambient temperature
• Needs a sound substrate with pull-off strength above 1.0 N/mm², laitance removed and thorough pre-wetting to saturated surface-dry
• May show harmless surface blooming after rain or in damp weather; it does not affect performance
• Must not be ponded or water-immersed before 7 days of curing
• Shelf life is 12 months from production — check the batch date and store between +10 °C and +35 °C, protected from frost

Selection & best practice

Specifications

Figures are taken from the Sika India Product Data Sheet for SikaTop-107 Seal IN (Aug 2022, v02.01). Older global SikaTop Seal-107 literature quotes a 20 kg unit at 4:1 — that configuration is not the Indian SKU. Always verify against the current project-specific PDS.

Industry use cases

How we position Sika SikaTop-107 Seal

SikaTop-107 Seal sits in the middle of Sika’s waterproofing family: for live, moving cracks or exposed roofs step up to a Sikalastic liquid-applied elastomeric membrane, and for below-ground tanking under high pressure consider Sika’s crystalline or bituminous systems. Pair it with SikaGrout for filling voids around penetrations and Sikadur epoxy products for crack injection where structural cracks are present. Within the system detail itself, reinforce large or demanding areas with Sika Fabric-50 glass mesh between coats, seal moving penetrations and joints with SikaSwell S-2 or a Sikaflex sealant, and finish a composite wet room with SikaCeram tile adhesive plus Sika SealTape F. Because Space Arc supplies multiple brands, we can also cross-specify equivalents where availability, the approved-vendor list or potable-water clearance dictates — Fosroc Nitocote CM210, Dr. Fixit’s cementitious coatings, MC-Bauchemie waterproofing systems and MYK LATICRETE all offer comparable two-part cementitious slurries. We help engineers and contractors pick the right grade for the actual water condition rather than defaulting to one product.

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