STP ShaliPrime Screed
A three-component epoxy primer engineered to lock heavy epoxy screed floors onto concrete, even when the slab still holds up to 15% residual moisture.
What is it?
A three-component (resin, hardener and filler) epoxy primer from STP that seals concrete and creates a strong bonding layer for epoxy screed floor systems.
Where is it used?
Concrete floors in warehouses, factories, chemical plants and workshops that are about to receive a heavy-duty epoxy mortar screed, including newly laid slabs at least 14 days old.
Why use it?
It penetrates and stabilises porous or slightly damp concrete and develops the high pull-off adhesion a thick screed needs, so the finished floor does not delaminate under traffic and load.
How is it applied?
The three components are blended by weight (1.0 : 0.85 : 6.65) with a slow-speed drill, then applied by brush, roller or squeegee at 0.20-0.40 kg/m2 and overcoated with screed within 4-6 hours.
About STP ShaliPrime Screed
STP ShaliPrime Screed is a purpose-built priming coat for epoxy screed flooring. Unlike a thin sealer, it arrives as three parts – a clear resin (Comp. A), an amber hardener (Comp. B) and a black filled component (Comp. C) – that are combined on site to produce a tough, filled epoxy film. That film does two jobs at once: it soaks into and consolidates the top layer of the concrete, and it leaves behind a chemically active, textured surface that a heavy epoxy screed can grip. For contractors laying 3 to 9 mm mortar screeds in industrial settings, this primer is the layer that decides whether the floor stays down for years or lifts at the first sign of thermal or mechanical stress.
What makes it practical on Indian sites is its tolerance for less-than-perfect substrates. The manufacturer states it can be applied to concrete carrying residual moisture up to 15%, and it can go over green concrete that is a minimum of 14 days old rather than forcing crews to wait a full month for the slab to dry. That flexibility matters when a project timeline is tight or when a slab simply refuses to reach bone-dry in a humid monsoon environment. Space Arc Engineering supplies ShaliPrime Screed as an authorised STP distributor across Delhi NCR and pan-India, and pairs it with the epoxy screed toppings it is designed to receive.
The technical insight
The primer works on two adhesion mechanisms working together. First is chemical bonding: fresh epoxy screed laid over the primer within the 4-6 hour overcoating window co-reacts with the still-active primer film, effectively fusing the two epoxy layers into one continuous system rather than stacking them. Second is mechanical keying: the filled, matt-textured surface the primer leaves behind gives the screed a rough profile to interlock with, multiplying the real contact area. The high solids, filled formulation is also what lets it cope with damp and green concrete – it seals the capillary pores that would otherwise let moisture vapour push up and blister the floor, and it consolidates the weak surface laitance of young concrete into a sound plane. Because it is a reactive thermoset, the chemistry is time-bound: pot life is only 40-45 minutes at 27 C, so mixed material must be spread within that window, and water cannot be added to stretch it – once it starts to gel, that batch is spent.
Where it is used
- Priming new or aged concrete before an epoxy mortar or self-levelling screed
- Sealing highly absorbent or porous concrete floors and screeds prior to topping
- Warehouse and distribution-centre floors receiving heavy-duty epoxy screed
- Factory and manufacturing shop floors under load and forklift traffic
- Chemical plant and process-area floors before a chemically resistant screed
- Priming slabs that carry residual moisture up to 15% where a moisture-sensitive primer would fail
- Bonding coat over green concrete a minimum of 14 days old to accelerate the flooring programme
- Repair and overlay areas where a fresh screed must bond to an existing concrete base
Key advantages
- Tolerates up to 15% residual moisture in the concrete, widening the site window for priming
- Can be applied over green concrete as young as 14 days rather than waiting the usual 28 days
- Three-component filled formulation builds a keyed, high-grip surface for heavy screeds
- Develops strong pull-off adhesion so thick screed systems resist delamination under load
- Applies simply by brush, roller or squeegee with ordinary site tools
- Smooth, matt finish that overcoats cleanly within a 4-6 hour window
- Supplied as a single 8.5 kg pre-weighed kit, removing on-site dosing guesswork
- Backed by STP’s construction-chemicals track record and Space Arc’s applicator support
Limitations & considerations
- Short pot life of 40-45 minutes at 27 C means mixed material must be used quickly and cannot be re-thinned with water
- Not recommended over water-ponded surfaces or on areas with active rising moisture
- High ambient humidity can cause amine blush or sweating on the film, which must be removed before further coats
- Requires substrate and ambient temperatures between 15 C and 40 C, so very cold or very hot conditions need managing
- Primed areas must not be covered with plastic sheet or allowed to condense while the film is wet
- Concrete must be sound and properly prepared (per SSPC-SP 13 guidance) – it will not compensate for weak, contaminated or unrepaired substrates
Selection & best practice
Prepare the concrete first: it must be at least 14 days old, sound, and free of curing compounds, oil, grease, dust, salts and laitance, mechanically cleaned in line with SSPC-SP 13 guidance, with all cracks, voids and dents repaired before priming. Mix by weight in the stated 1.0 : 0.85 : 6.65 ratio – add stirred Comp. B into Comp. A, then Comp. C, and blend for three minutes with a slow-speed drill (200-300 rpm) until fully homogeneous. Apply the mix at 0.20-0.40 kg/m2 (25-40 micron DFT) by brush, roller or squeegee using cross strokes for even coverage without clouding or air entrapment, and keep within the 40-45 minute pot life. Set both substrate and air temperature to 15-40 C. Lay the epoxy screed within the 4-6 hour overcoating interval so the layers chemically knit; if that window is missed or amine blush appears, treat the surface before proceeding. Do not sheet over or let condensation form on the wet film, and clean all tools with potable water immediately after use.
Specifications
| Composition | Three-component epoxy primer (A: resin, B: hardener, C: filled) |
| Colour | Comp. A clear, Comp. B amber, Comp. C black; mixed film smooth and matt |
| Mixing ratio (by weight) | A : B : C = 1.0 : 0.85 : 6.65 |
| Pot life (27 C, 55% RH) | 40-45 minutes |
| Theoretical coverage | 0.20-0.40 kg/m2 |
| Recommended DFT | 25-40 microns |
| Setting time / overcoating interval | 4 hours set; overcoat within 4-6 hours |
| Application temperature | Substrate and ambient +15 C min / +40 C max |
| Pack size / shelf life | 8.5 kg pack; 12 months unopened at 5-38 C |
Industry use cases
Warehousing & Logistics
Priming large concrete floor areas before a heavy epoxy screed that must withstand pallet racking loads and continuous forklift movement.
Manufacturing & Engineering
Preparing factory shop floors for chemically and mechanically resistant screed toppings in machining, assembly and process bays.
Chemical & Process Plants
Sealing and keying concrete ahead of a chemically resistant epoxy screed in areas exposed to spillage and aggressive cleaning.
Fast-track Fit-outs
Priming green concrete from 14 days old or slabs with up to 15% residual moisture so screed can be laid without waiting for full drying.
Floor Repair & Overlay
Bonding a new epoxy screed to an existing, prepared concrete base during refurbishment of worn or damaged industrial floors.
Frequently asked questions
Can ShaliPrime Screed be used on damp or green concrete?
What is the mixing ratio and how long is the pot life?
How much does one pack cover?
How soon should I lay the screed after priming?
What surface preparation does it need?
What is the pack size and shelf life?
How we position STP ShaliPrime Screed
ShaliPrime Screed sits at the base of STP’s epoxy flooring stack – use it as the priming layer beneath STP’s epoxy screed and self-levelling floor toppings (the ShaliFloor range) to keep the whole system within one compatible chemistry. Where the concrete is dry and a simpler two-component primer suffices, STP ShaliPrime 2E or the solvent-free 2E SF are the lighter-duty alternatives from the same family. For crack, void and surface repairs that must be completed before priming, pair it with an STP epoxy repair mortar. Across our other brands, Fosroc offers a directly equivalent industrial flooring line, and for structural bonding of fresh toppings to old concrete a Fosroc epoxy bonding agent is a proven complement. Space Arc can specify the right primer-screed-topping combination for your floor and traffic conditions.
Fosroc Nitobond EP — Choose the Fosroc epoxy bonding agent when the priority is fusing a fresh cementitious topping to an existing concrete base rather than sealing a porous slab specifically for an epoxy screed.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.