MC-Bauchemie MC-DUR 1491
A flexible epoxy-polysulfide coating built to keep concrete and steel alive in the environments that kill them fastest — marine spray, sewage gases and industrial chemicals.
What is it?
A two-component, epoxy resin-based flexible polysulfide coating supplied as a grey, semi-glossy protective film. Blending an epoxy backbone with a polysulfide modifier gives it the hardness of an epoxy coating and the give of a flexible membrane in one system.
Where is it used?
Concrete and steel in marine and coastal structures, sewage and effluent treatment works, water and waste channels, bridges, food-processing units, hospitals, aircraft hangars and garages.
Why use it?
Its water permeability and rapid chloride permeability both test out at nil, which shuts down the two mechanisms that actually corrode reinforcement, while the polysulfide content keeps the coating flexible enough to tolerate minor substrate movement instead of hairline-cracking like a straight epoxy.
How is it applied?
Two coats by brush, roller or airless spray at a minimum 250-micron wet film thickness per coat — first coat in one direction, second coat cross-hatched — over concrete of at least 25 N/mm² compressive strength or SA 2½ blast-cleaned steel, with an MC-DUR primer used first on old, dusty or rusty surfaces.
About MC-Bauchemie MC-DUR 1491
MC-DUR 1491 sits in an unusual spot in MC-Bauchemie’s coatings range: it isn’t chasing decorative flooring aesthetics, it’s built to keep concrete and steel structurally sound in exposures that actively try to destroy them. The epoxy-polysulfide hybrid chemistry is the point. A conventional epoxy coating is hard and chemically tough but can go brittle at the edges of a crack or a construction joint; a straight polysulfide is flexible but softer and less abrasion-resistant. MC-DUR 1491 is formulated to sit between the two — Shore D hardness of 50-plus at seven days for wear resistance, nil water permeability and nil rapid chloride permeability for corrosion protection, and enough flexibility in the film to move with the substrate rather than fight it.
For Indian project sites, that combination maps directly onto the structures that give engineers the most grief: RCC piers and jetty decks getting hammered by tidal chloride exposure, STP and ETP tanks where hydrogen sulphide and acidic condensate eat concrete from the inside, and steel members in coastal or industrial atmospheres where standard paint systems fail within a couple of monsoons. Space Arc Engineering supplies and applies MC-DUR 1491 across Delhi NCR and pan-India as part of the MC-DUR protective coatings line, typically specified alongside MC-DUR primers for compromised substrates and Nafuquick repair mortars where the concrete needs patching before coating.
The technical insight
The engineering logic of an epoxy-polysulfide blend is worth spelling out because it’s easy to conflate with a plain epoxy floor coating. Pure epoxy films are dimensionally stiff — excellent bond strength and chemical resistance, but limited elongation, so they tend to telegraph and eventually crack over any substrate movement, thermal cycling, or a hairline crack that opens and closes. Polysulfide resins go the other way: genuinely flexible and good at bridging minor movement, but on their own they’re softer, less abrasion-resistant and slower to build hardness. MC-DUR 1491 co-cures the two resin systems so the film picks up flexibility from the polysulfide fraction without giving up the epoxy’s hardness development — reaching Shore D ≥50 within seven days while still being described by the manufacturer as flexible rather than rigid. Combined with a nil result on both DIN 1048 water permeability and ASTM C1202 rapid chloride permeability testing, the practical effect is a coating that blocks the moisture and chloride ingress that drive rebar corrosion, on a substrate that isn’t perfectly crack-free or vibration-free — which describes most real marine and industrial concrete.
Where it is used
- Protective coating on RCC piers, seawalls and jetty decks in marine and coastal structures
- Lining for sewage and effluent treatment structures — STP/ETP tanks, channels, sumps and culverts
- Protective coating for bridge substructures and other chloride-exposed infrastructure
- Hygienic, easy-clean floor and wall coating for food-processing units
- Protective coating for hospital and laboratory floors/walls where a chemical- and stain-resistant finish is needed
- Coating for structural steel exposed to marine or industrial atmospheres, over an SA 2½ blast-cleaned surface
- Interior coating for aircraft hangars and vehicle garages
- Anti-carbonation protective recoat over rehabilitated RCC structures
Key advantages
- Nil water permeability and nil rapid chloride permeability (DIN 1048, ASTM C1202) directly target the two main drivers of rebar corrosion
- Flexible polysulfide component lets the film tolerate minor substrate movement instead of cracking the way a rigid epoxy can
- Shore D hardness ≥50 at 7 days gives solid abrasion resistance for foot and light-duty traffic
- Good UV resistance (500 hrs per ASTM G-53-58) means it holds up better in semi-exposed outdoor use than many pure epoxies that chalk quickly
- Resistant to diesel oil, dilute acids/alkalis and a range of organic solvents, useful in mixed industrial exposure
- Non-toxic, semi-glossy finish that’s easy to clean — a genuine fit for food-processing, hospital and lab environments
- Applies by brush, roller or airless spray, so it adapts to tight or awkward site conditions
- High volume of solids (98±2%) means less shrinkage and thinner-film risk than solvent-heavy alternatives
Limitations & considerations
- Standard stock colour is grey; other shades typically need to be special-ordered, which can stretch procurement lead time
- Application window is narrow — work stops above 35°C surface temperature and below 15°C ambient/substrate temperature, which needs planning around Indian summer and monsoon conditions
- Pot life is only 50-60 minutes at 27°C, so mixing has to be batched tightly on larger pours, especially in hotter weather
- Substrate prep requirements are strict — concrete needs >25 N/mm² compressive strength and 1.5 N/mm² pull-off strength, steel needs SA 2½ blast cleaning — so surface prep is a real cost and schedule item, not an afterthought
- It’s a protective coating, not a wearing-course flooring system; for heavy forklift or vehicular trafficked floors a dedicated flooring topping is the more appropriate product
- Full cure takes 7 days at 27°C, so immersion service or chemical exposure needs to be scheduled after that, not immediately after the second coat
Selection & best practice
Treat surface preparation as the make-or-break step: concrete has to be sound, laitance-free and free of old release oils or curing compound residue, with any bug-holes or blowholes filled using a Nafuquick mortar before coating starts, and steel has to be blast-cleaned to SA 2½ per DIN 55928 Part 4, not just wire-brushed. On old, dusty, or lightly rusted substrates that can’t be brought to that standard, run an MC-DUR range primer first rather than coating directly — skipping the primer on a marginal substrate is the single most common cause of early delamination on site. Mix in small batches given the 50-60 minute pot life at 27°C, combining the colour paste into the base first and only then adding the hardener, mixing for a full three minutes at low speed (max 300 rpm) to avoid whipping air into the mix. Apply the first coat in one direction and the second, once the first is fully dry, at right angles to it — this cross-hatching is what closes pinholes and evens out the film. Hold the 250-micron wet-film-thickness target per coat rather than stretching coverage; under-thickness is invisible until the coating starts failing under chloride or chemical exposure. Stop work outright if surface temperature exceeds 35°C or drops below 15°C, and clean tools with MC-Thinner EP or MC-Clean EP only — water and water-based cleaners will not work on this system.
Specifications
| Chemistry | Epoxy resin-based flexible polysulfide coating (2-component) |
| Pot life | 50-60 minutes @ 27°C |
| Volume of solids | 98 ±2% |
| Wet film thickness | 250 microns per coat, minimum 2 coats |
| Shore D hardness | ≥50 at 7 days (ASTM D2240) |
| Water permeability | Nil (DIN 1048) |
| Rapid chloride permeability | Nil (ASTM C1202) |
| Coverage | 700 g/m² (0.50 L) per 2 coats |
| Full cure | 7 days @ 27°C |
| Pack sizes | 7 kg (5 L) and 21 kg (15 L) |
Industry use cases
Marine & coastal infrastructure
Protective coating on RCC jetty decks, piers and seawalls exposed to tidal and chloride-laden spray, where nil chloride permeability protects the reinforcement.
Water & wastewater utilities
Lining for STP/ETP tanks, effluent channels and sumps subject to acidic condensate and hydrogen sulphide attack that eats ordinary concrete coatings.
Food & beverage processing
Hygienic, easy-clean semi-gloss coating for plant floors and walls needing chemical and stain resistance without a decorative flooring build-up.
Transport infrastructure
Protective recoat on bridge substructure and other chloride-exposed RCC elements as part of a rehabilitation scope alongside repair mortars.
Healthcare & institutional
Chemical-resistant, hygienic coating for hospital and laboratory floor/wall surfaces where surfaces need to withstand cleaning agents and foot traffic.
Frequently asked questions
Is MC-DUR 1491 a flooring product I can use for a trafficked warehouse floor?
Can it go straight over an old painted concrete surface?
What primer does it need on rusty or dusty substrates?
How many coats and what thickness should we plan for?
What’s the shelf life and how should we store it on site?
Can this be applied during Mumbai or coastal monsoon conditions?
How we position MC-Bauchemie MC-DUR 1491
Within the MC-Bauchemie family, MC-DUR 1491 is best specified as a system rather than standalone: pair it with an MC-DUR range primer whenever the substrate is old, dusty, or lightly corroded, and with a Nafuquick repair mortar where honeycombing or spalling needs patching before the coating goes on. If the actual requirement is a heavy-duty trafficked industrial floor rather than a corrosion-protection lining, Space Arc’s MC-Floor range is the more appropriate MC-Bauchemie product to bring into the conversation instead. On the competitive side, Fosroc’s own epoxy-polysulphide protective coating, Nitocote EPS, is a genuine equivalent in chemistry and intended use, and is a reasonable alternative for specifiers already standardised on Fosroc systems or who need documented crack-bridging on sewage and effluent tank linings.
Fosroc Nitocote EPS — Specifiers already standardised on Fosroc’s protective-coatings range, or who need documented crack-bridging (up to 2.5 mm) on sewage and effluent tank linings, may prefer Nitocote EPS — Fosroc’s own two-component epoxy-polysulphide coating built on essentially the same hybrid chemistry as MC-DUR 1491.
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