Overview
Polyurethane coatings are among the most widely used protective and decorative finishes in the coatings industry. They combine hardness with flexibility in a way that few other chemistries manage, which is why they remain the default choice for bridges, ships, aircraft, machinery and architectural finishes.
Delshine manufactures two distinct polyurethane product types. DSBY-35 is a rigid, closed-cell spray polyurethane foam used to insulate and structurally fill cavities, applied hot and expanding to fill irregular geometry. DSLX-E is a cast polyurethane elastomer with an unfixed mixing ratio, used where a tough, rubber-like, abrasion-resistant elastomer layer is needed rather than a foam.
The difference matters commercially. Rigid spray foam is a volume product measured in cubic metres and priced on density and thickness. Cast elastomer is a thin-film product measured in square metres and priced on film thickness and surface area.
Polyurethane Elastomer (Casting): Casting by heating unfixed ratio
Product identification
The identifiers below are the ones printed on the drum and quoted on the purchase order. Always order and dispatch by code, because the grade and the zinc or temperature variant cannot be inferred from the trade name alone.
| Product code | DSLX-E |
|---|---|
| Trade name | Polyurethane Elastomer (Casting) |
| Category | Polyurethane systems |
| System role | Topcoat - exposed finish of the system |
| Manufacturer description | Casting by heating unfixed ratio |
Where this product is used
- Thermal insulation of walls, roofs, tanks and pipework
- Structural filling of gaps, voids and irregular cavity sections
- Bonding and sealing of panels, joints and prefabricated modules
- Cold-room and refrigerated storage insulation
- Pipe insulation and chilled-water line coating
- Cast elastomer linings for abrasion and impact-prone surfaces
- Marine deck and superstructure coating
- Bridge and infrastructure steelwork protection
How it works in the coating system
The topcoat is the visible, exposed layer of the system. It provides the colour, the gloss and the final resistance to weathering, UV, chemicals and mechanical wear — the properties the specifier and the owner actually see and rely on.
Because it is the only coat fully exposed to the service environment, the choice of topcoat chemistry is the single decision that most affects how a coating system ages. A system that is under-specified at the topcoat will look good on day one and disappoint in five years.
Purpose in the system: The final coat of the system, applied over the intermediate coat.
Technical properties
The values below are the typical published range for this product family. The exact figures for your batch are confirmed on the batch certificate and the current technical data sheet.
| Role in the coating system | Polyurethane — rigid foam (insulation) and elastomer (casting) |
|---|---|
| Volume solids | 100 % (reacting) |
| Mixing ratio by volume | 1:1 by volume for the foam (250 kg A + 250 kg B); 100:30 for the cast elastomer |
| Typical dry film thickness | 30–200 mm sprayed foam; 2–20 mm cast elastomer |
| Theoretical coverage | Theoretical 1 m³ per 1 m³ of mixed foam; elastomer by volume |
| Application methods | Plural-component hot spray · casting into moulds |
| Application temperature window | Component temperature 60–80 °C for spray; 40–50 °C for casting |
| Suitable substrates | Steel, concrete, timber; direct spray to substrate for foam |
| Finish / appearance | Closed-cell rigid foam (off-white) or coloured cast elastomer |
| Principal resistance | Thermal insulation, compressive load, impact |
| UV resistance | Foam requires a UV-resistant facing or cladding |
| Adhesion to prepared steel | Excellent to prepared steel and concrete |
| Salt spray performance | > 1,000 h in the foam system |
| Chemical resistance | Resistant to oils, fuels and many solvents; attacked by strong acids |
| Abrasion resistance | High compressive strength, low surface abrasion resistance |
| Flash point | 110–140 °C |
| Shelf life | 6 months unopened in the original drums |
| Density | 35–45 kg/m³ (foam); 1.15–1.25 g/cm³ (elastomer) |
| Pack sizes | 250 kg + 250 kg drum sets; 1 kg–20 kg kits (elastomer) |
Surface preparation
- Prepare the substrate to be clean, dry, free of oil, grease and loose rust, and of adequate mechanical strength to hold the coating.
- Abrasive blast steel to Sa 2½ for a durable result, or at minimum mechanically abrade and remove all rust to a sound, bright or near-bright surface.
- For cavity filling, seal all porous surfaces — open-cell substrates such as timber and some foams will absorb the component and create voids.
- Mask off areas that must remain free of foam and check that the spray gun is set up for the correct expansion ratio.
- Ensure adequate ventilation and that the substrate temperature is within the application window stated on the data sheet.
Application procedure
Apply by spray for the best appearance and film uniformity, by roller for large flat areas, or by brush where access is restricted.
Aim for a consistent wet film across the whole area. Overlapping passes should be kept wet to avoid a lap line in the finish.
Plan the work so that the coating is applied in manufacturable quantities — a full kit should be mixed and used within the pot life, and any surplus should be discarded rather than saved.
Mixing, ratio and induction time
Two-pack finishes are mixed at the ratio stated on the data sheet, commonly 4:1 or 5:1 by volume for epoxy and 3:1 for polyaspartic and acrylic polyurethane. Use a proper mixing gauge — a mix that is even a few percent off ratio will cure differently and may not meet the published properties.
Cure, recoat window and service readiness
Surface dry in 2 to 6 hours, recoatable in 12 to 24 hours, and fully cured in 7 days. Do not place the structure into service, immersion or heavy loading before full cure, even though the surface will feel dry much earlier.
Coverage and thickness calculation
Typical dry film thickness is 60-100 µm for a conventional finish and 40-60 µm for a high-build polyurethane finish. At 80 µm, one litre covers roughly 8-10 m². Two coats are usually specified where colour, gloss uniformity or coverage hiding matter.
Technical note. Coverage (m²/litre) = (volume solids × 10) / DFT (µm)
Worked example
| Specified DFT | 1000 µm |
|---|---|
| Volume solids | 100 % |
| Theoretical coverage | 1.00 m²/litre |
| Total for the area | 50 m² → 50.0 litres |
Advantages
- Excellent mechanical strength with outstanding impact and abrasion resistance in the elastomeric grades.
- Superior UV and weather resistance — aliphatic grades do not chalk or yellow, and they retain gloss for many years.
- Good chemical resistance to oils, fuels, solvents and cleaning agents.
- Seamless, monolithic protection with no lap joints to fail.
- Excellent adhesion to steel, concrete, aluminium and wood.
- Spray polyurethane foam provides both insulation and structural support in a single pass.
Limitations and precautions
- Isocyanate components require proper respiratory protection and ventilation during application.
- Aromatic grades discolour under UV and must be topcoated for external use.
- Surface preparation and film thickness both strongly affect adhesion — thin, poorly prepared coats will peel.
- Polyurethane is not the right choice for continuous immersion in strong acids or alkalis without a specific chemical-resistant grade.
- Hot-spray application requires correctly proportioning and heated equipment; cold-applied grades have different performance limits.
Storage and shelf life
- Store component A and B in their original sealed containers in a cool, dry, ventilated place between 5 °C and 35 °C.
- Protect from moisture and direct sunlight. Isocyanate components react with atmospheric moisture if the container is left open.
- Do not store near foodstuffs or strong oxidisers.
- Rotate stock first-in-first-out and observe the labelled shelf life.
Safety, PPE and ventilation
- Treat all isocyanate components as sensitising agents. Use air-supplied respiratory protection for spray application.
- Wear chemical-resistant gloves, goggles and coveralls; a coverall is essential because overspray on skin can cause dermatitis.
- Ensure the extraction system is rated for the volume of spray being applied.
- Keep the workplace free of ignition sources and never weld or cut near uncured polyurethane.
Quality control and inspection
- Check colour and gloss against the approved sample or RAL reference before starting the full area.
- Measure DFT and check for thin spots, particularly over welds, edges and connections.
- Inspect the finished surface for lap marks, sag, orange peel, dust inclusion and solvent entrapment before accepting the coat.
Pricing and how to order
Delshine quotes this product per square metre at a specified dry film thickness, or per drum/litre depending on the project. The material cost is usually the smallest part of the installed cost — surface preparation, access and application labour dominate. Send us the substrate, the service conditions and the required DFT and our technical team will return a full system recommendation with a firm price.
Rigid spray polyurethane foam is priced per cubic metre of applied foam, with the cost driven by density and thickness. Cast polyurethane elastomer is priced per square metre at a specified film thickness. Both figures assume a properly prepared substrate — preparation and scaffolding usually cost more than the material itself on a large structure.
Frequently asked questions
The questions below are the ones our technical team is asked most often about this product family.
What is spray polyurethane foam used for?
Spray polyurethane foam (DSBY-35) is used for thermal insulation and structural cavity filling. It is applied hot as a two-component liquid that expands in the cavity, forming a rigid closed-cell insulation that also stiffens and supports the structure. Typical uses include cold rooms, pipe insulation, tank insulation and filling irregular voids in prefabricated modules.
How thick should polyurethane insulation be?
It depends on the required thermal performance. As a rough guide, 30-50 mm of rigid spray polyurethane foam is equivalent to 80-120 mm of mineral wool for the same U-value. Calculate against your target heat loss and local building regulations rather than copying a thickness from another project.
Can polyurethane be applied over steel?
Yes. Prepare the steel to Sa 2½ by abrasive blasting, then apply a compatible epoxy anticorrosive primer — for example a zinc-rich epoxy such as DSEH-104 or a high-build modified epoxy primer. The polyurethane is applied over the primer, not directly onto bare metal.
Is polyurethane coating food safe?
Not by default. Polyurethane is not generally approved for direct food contact. For potable water or food-processing environments, specify a coating that carries the relevant certification — DSEH-701 epoxy drinking water tank coating is FDA approved for that purpose.
Can polyurethane be sprayed in cold weather?
Hot-spray systems need the components brought up to temperature, and the substrate must be above the minimum application temperature stated on the data sheet — usually around 5-10 °C. Below that, plan a heated environment or schedule the work for warmer conditions.
What is the difference between rigid foam and cast elastomer?
Rigid spray foam (DSBY-35) is a closed-cell, rigid, insulating material that expands to fill a cavity. Cast polyurethane elastomer (DSLX-E) is a tough, flexible, rubber-like coating poured or cast at a controlled thickness onto a prepared surface. Foam insulates and fills; elastomer coats, seals and resists abrasion.
Related products
These products are normally used in the same system as the product described above.
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