About STP ShaliProtek PuR H

ShaliProtek® PuR H is STP Limited’s fast-setting entry in its ShaliProtek polyurea range — a two-component, 100% solids, zero-VOC coating built by reacting a polyurea-polyurethane hybrid resin with its hardener inside a heated spray gun rather than in a bucket. The reaction is close to instantaneous: STP’s own data sheet lists a 10-15 second gel time and a 60-80 second tack-free time at 27°C/60% RH, which is what lets applicators build the recommended 1.5 mm minimum dry film thickness in a single spray pass on a roof, tunnel wall or pipeline, without the multiple coats, recoat waits and pinhole risk that slower solvent-based PU membranes carry.

For Delhi NCR and Pan-India project teams, that speed matters as much as the film properties on the data sheet. A metal roof or tank that can only be shut down for a single working shift, or a tunnel section that needs to reopen quickly, is exactly the use case this chemistry was built for. Once cured, the coating carries genuinely strong numbers — 450% elongation, static crack-bridging to 3.5 mm, no cracking under EN 1062-7 dynamic bridging, and pull-off adhesion above 6 MPa on primed steel — so the speed doesn’t come at the cost of long-term flexibility. Space Arc supplies and specifies it as an authorised STP distributor for roofing, pipeline and tunnel waterproofing scopes across the region.

The technical insight

The “hybrid” in the name is the technical story. Pure polyurea sets almost instantly and shrugs off ambient moisture during spraying, but can be difficult to control on detailed or vertical work; polyurethane segments soften that reactivity slightly and improve wetting and adhesion to the primer coat, while still keeping gel time low enough for high-build single-pass work. That reactivity is also why the equipment side of the specification isn’t optional — STP calls for plural-feed airless spray equipment with resin and hardener heated to 60-70°C and a tip pressure of 100-150 bar, because viscosity and atomisation at the gun are what keep the film pinhole-free at 1.5 mm-plus DFT. It is not a coating a site crew can hand-mix and roll on.

Where it is used

• Waterproofing of RCC and metal roof decks, including walkable/trafficked roofs
• Tunnel lining waterproofing and protective coating
• External anti-corrosion protective coating on metallic pipelines
• Protective coating on metallic and cementitious surfaces exposed to saline or marine water
• Silo and hopper linings subject to abrasion and chemical exposure
• Refurbishment topcoat over existing, sound polyurethane waterproofing membranes
• Protective jacketing over PU foam insulation on cold-store roofs and pre-insulated piping
• Secondary containment and water-retaining structures needing hydrostatic resistance

Key advantages

• 100% solids, zero-VOC formulation builds full film thickness in one pass, with none of the shrinkage or pinholing common to solvent-based PU coatings
• 10-15 second gel time and 60-80 second tack-free time mean a roof or tank can often be coated and back in service within a single shift
• 450% elongation plus documented static (3.5 mm) and dynamic (EN 1062-7, no cracks) crack-bridging — genuinely flexible under movement, not just on paper
• Pull-off adhesion above 2.6 MPa on concrete and above 6.0 MPa on primed metal keeps the film from blistering or delaminating
• -20°C to +90°C service range covers both unshaded metal roofs in Indian summer heat and cold-chain/insulated applications
• 7 bar hydrostatic pressure resistance and pass results against mineral/hydraulic oils, fuels, seal water and dilute acids/alkalis widen its use beyond plain roofing
• Can be sprayed directly over existing, sound polyurethane waterproofing coatings, useful for refurbishment without full strip-back
• High mechanical strength (Shore A 85, Taber abrasion loss of only 60 mg) suited to trafficked and abrasion-exposed decks

Limitations & considerations

• Application-critical: it only goes down through heated plural-component airless spray rigs (60-70°C, 100-150 bar) run by a trained polyurea crew — there is no brush, roller or DIY route for this product
• The sub-20-second gel time leaves almost no margin for error on site; an inexperienced sprayer will get ridging, poor flow-out or wastage rather than a smooth film
• Correct priming (ShaliPrime PUM on concrete, ShaliPrime 2E on metal) and correct substrate prep (28-day-cured concrete, SA 2½ blasted steel) are mandatory — the adhesion figures on the data sheet assume both were done properly
• Sold only as a matched 220 kg + 224 kg two-drum kit, so it is specified for full roof, pipeline or tunnel scopes rather than small patch repairs
• Standard colours are black or grey only; projects needing a specific aesthetic shade on an exposed roof need a compatible UV-stable topcoat, budgeted separately
• As with other fast-reactive spray coatings, substrate moisture or contamination at the time of spraying can cause blistering, so a dew-point check before each shift is not optional

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliProtek PuR H

Within STP’s own polyurea/polyurethane line, PuR H sits at the fast-setting, high-build end: ShaliProtek PuR 40 and PuR L give a longer working, brushable window for smaller or more detailed work, PuR 100 is another fast-setting spray grade, and the ShaliUrethane LHM/LHM 2K/BTD family covers roller-applied liquid PU membranes for jobs that don’t justify mobilising spray equipment. Space Arc, as an authorised STP distributor and applicator, specifies between these based on roof size, access and shift-time constraints rather than pushing one SKU. We haven’t found a genuinely equivalent spray-applied hybrid polyurea in the Fosroc range carried on our site — Fosroc’s closest PU offer, Brushbond Ultraflex, is a brush/roller system rather than a heated plural-component spray coating, so it isn’t treated here as a like-for-like substitute.

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