About STP Extender 36

STP Extender 36 is a graded silica aggregate manufactured by STP Limited (formerly Shalimar Tar Products, part of the Turner Morrison Group), one of India’s long-established construction-chemical houses. It sits in STP’s family of inert fillers alongside the coarser Extender 18 and the finer Extender 90 and Extender 201 quartz powder. The “36” grade is a medium-to-fine cut of silicon dioxide, chosen for the sweet spot where an epoxy or polyurethane screed needs enough body to build thickness and take abrasion, but still trowels and self-levels cleanly. Because it is pure inert silica, it does not participate in the chemical cure of the resin; it simply occupies volume, carries load and gives the hardened matrix its wearing surface.

For contractors and flooring applicators, the value is practical. A litre of epoxy binder is expensive; a bag of graded silica is not. By extending the resin with STP Extender 36 at the correct ratio, you convert a thin, costly coat into a thick, hard-wearing screed at a fraction of the material cost per millimetre laid. It is equally at home as a broadcast aggregate, scattered onto a freshly rolled coat to lock in an anti-slip profile before the seal coat goes down. Space Arc Engineering stocks and delivers it across Delhi NCR and Pan-India for warehouse, factory, workshop and parking-deck floor packages.

The technical insight

Resin flooring is a two-part story: the binder (epoxy or PU) does the sticking and chemistry, while the aggregate does the volume and the wearing. STP Extender 36 works because silicon dioxide is one of the hardest, most chemically stable common minerals — it shrugs off the alkalis, oils and abrasion that destroy a neat resin film. When you fill an epoxy with a well-graded medium-to-fine silica, load transfers through a rigid mineral skeleton rather than through the softer polymer alone, so the floor resists indentation and wear far better than unfilled resin. The medium-to-fine grading matters: too coarse and the mix will not level or trowel smoothly; too fine and it thickens the resin into an unworkable paste and starves the surface of grip. The 36 cut is graded to stay suspended and wet-out fully during mixing, giving a homogeneous screed with no dry pockets. Used as a broadcast, the same particle size builds a consistent micro-texture that holds an anti-slip rating without tearing up boots or trolley wheels.

Where it is used

• Body filler to thicken solvent-free epoxy screeds and build screed depth economically
• Cost-effective extension of epoxy and polyurethane floor coatings
• Broadcast aggregate scattered onto wet coats to create an anti-slip textured surface
• Filler component in self-levelling epoxy and PU underlay and topping formulations
• Bulking aggregate in trowel-applied heavy-duty industrial floor screeds
• Aggregate for repair mortars and patch systems based on epoxy or PU binders
• Blended into ShaliFloor and other resin screed systems as the graded silica phase
• Texture coat for ramps, loading bays and wet-process areas needing extra grip

Key advantages

• Chemically inert and non-toxic silicon dioxide that does not react with or weaken the resin binder
• Substantially lowers material cost per millimetre of screed by extending expensive resin with low-cost aggregate
• Medium-to-fine grading wets out cleanly for a homogeneous, workable mix with no dry pockets
• Improves abrasion and wear resistance of the cured epoxy or polyurethane matrix
• Dual use: stir-in as a body filler or broadcast as an anti-slip texture aggregate
• Consistent factory grading gives repeatable mixes batch to batch across a large floor
• Compatible with epoxy, polyurethane and most cementitious coating systems
• Off-white colour that will not muddy pigmented or light-coloured topcoats

Limitations & considerations

• It is an inert filler, not a binder — it has no adhesive or curing properties on its own and must always be combined with a resin system
• Correct dosage is formulation-specific; over-filling starves the mix of resin and produces a weak, porous, under-bound screed
• As dry crystalline silica it must be handled with respiratory protection to avoid inhaling dust during mixing and broadcasting
• It does not add chemical resistance beyond the inherent resistance of silica; aggressive-chemical floors still depend on the resin choice
• Aggregate must be kept dry before use — damp silica clumps and interferes with resin wet-out and cure

Selection & best practice

Specifications

Industry use cases

How we position STP Extender 36

STP Extender 36 is best specified as part of a complete STP resin-flooring package: pair it with a ShaliFloor epoxy or PU screed system as the graded silica phase, step up to STP Extender 18 where a coarser, deeper screed is needed, or use Extender 90 as a dedicated slip-resistant additive and Extender 201 quartz powder for finer fillers and waterproofing mixes. Where a client would rather buy a warranted, factory-batched system than blend loose aggregate into resin on site, Space Arc also supplies the equivalent Fosroc line — the Fosroc Nitoflor epoxy screeds already carry their graded silica within the kit, giving single-source accountability for demanding industrial floors.

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