Overview
Epoxy coatings are the workhorse of industrial protective coating. A resin and a curing agent react to form a rigid, crosslinked film with outstanding adhesion, chemical resistance and durability, and they remain the most widely used protective coating in the world for good reason.
Delshine manufactures a complete epoxy system: zinc-rich and shop primers for steel, surface-tolerant and non-ferrous primers, micaceous iron oxide and epoxy tie coats, phenolic and vinyl ester topcoats, and specialist coatings for potable water, ballast tanks, cargo holds and offshore structures.
Understanding the layer is what makes epoxy work. A zinc-rich primer provides sacrificial protection, an epoxy intermediate provides barrier protection and film build, and a topcoat provides the chemical and UV resistance. Removing any one of those layers from the specification usually means the system will not deliver the service life the design assumed.
Modified Epoxy Nonferrous Metal Primer: Zinc yellow
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 | DSH02-7 |
|---|---|
| Trade name | Modified Epoxy Nonferrous Metal Primer |
| Category | Epoxy coatings |
| System role | Primer - first coat on the prepared substrate |
| Manufacturer description | Zinc yellow |
Where this product is used
- Protective coating of pipelines, tanks, vessels and process equipment
- Marine and offshore structures, hulls and topside equipment
- Bridges, cranes and heavy structural steelwork
- Petrochemical and chemical process plants
- Industrial flooring, warehouses and workshops
- Drinking water tanks and potable water infrastructure
- Ballast tanks, bilge areas and ship cargo holds
- Automotive, aerospace and industrial machinery
How it works in the coating system
A primer is the first layer in the coating system, and it decides how well everything that follows will adhere. Its job is to wet out the prepared substrate, key into its surface, and hold the coating together as one film.
Applied thin, a primer wets and anchors. Applied too thick, it becomes brittle, stresses the substrate and can peel as a sheet. The right dry film thickness for a primer is the one that covers the surface completely without building a film that can crack.
Purpose in the system: Applied directly to the prepared substrate, before any intermediate coat or topcoat.
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 | Epoxy coating system component — primer, intermediate coat, topcoat or sealer |
|---|---|
| Volume solids | 55–100 % depending on grade |
| Mixing ratio by volume | 4:1 or 5:1 by volume for the two-pack grades; single component where stated |
| Typical dry film thickness | 40–80 µm (primer) · 100–200 µm (intermediate) · 60–100 µm (topcoat) |
| Theoretical coverage | 6–14 m²/litre per coat depending on DFT and solids |
| Application methods | Airless spray · conventional spray · brush · roller |
| Application temperature window | 5–40 °C substrate; not above 95 % RH or within 3 °C of dew point |
| Suitable substrates | Prepared steel, concrete, masonry, galvanised surfaces (with the right primer) |
| Finish / appearance | Full colour range; gloss, semi-gloss, satin or matt |
| Principal resistance | Corrosion, chemicals, abrasion, solvents, water |
| UV resistance | Aromatic epoxies chalk under UV — always overcoat with a UV-resistant finish |
| Adhesion to prepared steel | > 5 MPa pull-off on Sa 2½ blasted steel |
| Salt spray performance | > 1,000 h for primers; > 3,000 h for high-build intermediates |
| Chemical resistance | Good against fuels, oils, acids and alkalis in the epoxy range |
| Abrasion resistance | Good; the glass flake and MIO grades are the abrasion-resistant options |
| Flash point | 18–32 °C |
| Shelf life | 12–24 months unopened |
| Density | 1.05–1.65 g/cm³ |
| Pack sizes | 1 kg–25 kg kits; 200 kg drums for the production grades |
Surface preparation
- Abrasive blast steel to Sa 2½ (ISO 8501-1) as the default, or to Sa 3 where the coating system or the specification calls for it. For non-blasted preparation, grind to at least St 3 and accept that adhesion and service life will be reduced.
- Remove all soluble corrosion salts with fresh water washing and test the surface for chloride contamination. Salt under a crossovercoat causes blistering that can appear months later.
- Remove all oils, greases and welding residues. Use a suitable solvent cleaner and a clean, lint-free cloth for final wipe-down.
- Round sharp edges to a minimum 2 mm radius and grind welds smooth. Never coat over an undercut weld or a sharp edge.
- Check the ambient conditions: the surface must be at least 3 °C above the dew point, the air temperature above 10 °C, and the relative humidity below 75-80%.
- Plan the coating sequence and observe the recoat window. Epoxy primers must be topcoated within their stated interval or the surface must be abraded and re-cleaned.
Application procedure
Apply by brush, roller, conventional air spray or airless spray depending on the product. Primers are usually thin enough to spray well and wet out a blasted surface completely.
Work at a consistent wet film thickness and avoid over-application at edges, welds and connections — sags and runs at these details are the most common primer defect.
Allow the primer to reach the specified state before overcoating. On some systems a primer should be topcoated while it is still slightly tacky for best intercoat adhesion; on others a full cure with an abrasion between coats is required.
Mixing, ratio and induction time
Two-pack primers are mixed in the ratio stated on the data sheet, typically 4:1 or 5:1 by volume for epoxy primers and 3:1 for polyaspartic systems. Allow the full induction time before thinning and application, and observe the pot life strictly — a primer that has begun to gel will not perform.
Cure, recoat window and service readiness
Recoat windows depend on temperature, humidity and film thickness, but a typical epoxy primer is recoatable after 12 to 24 hours at 20-25 °C and needs 7 days for full cure. Polyaspartic primers cure far faster and may be recoatable within 2 to 4 hours. Exceeding the maximum recoat interval requires the surface to be abraded and re-cleaned before the next coat.
Coverage and thickness calculation
Typical dry film thickness is 40-80 µm for a conventional primer and 60-100 µm for a high-build anticorrosive primer. At 60 µm, one litre covers roughly 12-14 m². Always measure the wet film and calculate back from the solids content to confirm the specified DFT is being achieved.
Technical note. Coverage (m²/litre) = (volume solids × 10) / DFT (µm)
Worked example
| Specified DFT | 125 µm |
|---|---|
| Volume solids | 70 % |
| Theoretical coverage | 5.60 m²/litre |
| Total for the area | 100 m² → 560.0 litres |
Advantages
- Excellent adhesion to steel, concrete, aluminium and properly prepared masonry.
- Very good resistance to oils, fuels, solvents, acids and alkalis when the correct chemical-resistant grade is specified.
- High film build achievable in fewer coats than alkyd systems, reducing labour and programme.
- Zinc-rich epoxy gives cathodic sacrificial protection that protects the steel even where the film is locally damaged.
- Excellent abrasion and impact resistance in the high-build and glass flake grades.
- Certified options available for potable water (FDA), ship classification (CCS) and European conformity (CE).
Limitations and precautions
- Most epoxies have limited UV resistance and will chalk and degrade in direct sunlight — a topcoat is required for exterior service.
- Aromatic epoxy coatings will yellow noticeably, which matters for light-coloured decorative finishes.
- Epoxy has a defined pot life and induction time that cannot be ignored. Mixing more than can be used in the pot life wastes money.
- Cold and humid weather slows cure and can cause amine blush, which compromises intercoat adhesion.
- Epoxy is not suitable for continuous immersion in strong acids or for food contact without the specific certified grade.
Storage and shelf life
- Store component A and B in their original sealed containers in a cool, dry, ventilated store between 5 °C and 35 °C.
- Do not store in direct sunlight or above 40 °C. Do not allow the components to freeze.
- Keep the containers tightly closed — the hardener reacts with atmospheric moisture and loses effectiveness.
- Rotate stock using first-in-first-out and observe the shelf life stated on the label, typically 12 months unopened.
Safety, PPE and ventilation
- Epoxy hardeners contain amines and epoxy resins can cause dermatitis. Wear chemical-resistant gloves, safety goggles and protective clothing.
- Use an organic-vapour cartridge respirator when mixing or spraying in poorly ventilated spaces.
- Ensure adequate ventilation during mixing and application. Epoxy vapour at high concentration is sensitising.
- Wash skin immediately with soap and water if contact occurs and seek medical advice for persistent irritation.
- Dispose of mixed surplus epoxy and solvent through a licensed contractor; do not allow it into drains.
Quality control and inspection
- Check the surface preparation standard and the blast profile before coating begins — this is recorded on the inspection report.
- Verify film thickness by wet film gauge during application and by magnetic induction gauge or dry film readings on the completed coat.
- Holiday test the primer before overcoating, particularly over welds, connections and edges.
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.
Epoxy coatings are priced per square metre at a specified dry film thickness. The total system cost is dominated by surface preparation and by the number of coats. For a typical three-coat system at 250 µm total DFT on 1,000 m², budget for blasting, primer, intermediate and topcoat separately so that a reduction in any one layer is visible as a commercial decision rather than an accident.
Frequently asked questions
The questions below are the ones our technical team is asked most often about this product family.
What is a zinc-rich epoxy primer and when should I use it?
A zinc-rich epoxy primer contains a very high loading of metallic zinc powder. The zinc corrodes preferentially to the steel, so the primer protects cathodically even where the film has been damaged to bare metal — it is sacrificial protection rather than barrier protection. Specify it on any steel structure in a corrosive atmosphere: offshore, marine, industrial and chemical plant environments.
What is the difference between Sa 2½ and Sa 3 blasting?
Sa 2½ is thorough blast cleaning: at least 95% of the surface must be free of visible residues and the surface must have a uniform matte metal surface. Sa 3 is more thorough still — at least 95% of the surface must be free of visible residues and show the bright metal beneath. Sa 2½ is the normal standard for protective coating systems and Sa 3 is specified where the coating system or client standard demands the highest level of preparation.
What is epoxy coating pot life and why does it matter?
Pot life is the period after mixing during which the epoxy remains workable. A typical 4:1 epoxy has a pot life of 2 to 4 hours at 20-25 °C and considerably less in hot weather. Once the pot life expires the material gels in the bucket and cannot be used. Induction time — the period that must elapse after mixing before application — also matters, because applying too early can cause solvent entrapment.
Can epoxy be applied over concrete?
Yes, and epoxy is one of the best coatings for concrete floors and structures, but the preparation is specific. The concrete must be mechanically ground or shot-blasted to open the surface, all laitance removed, and any cracks repaired. Use a concrete-compatible primer such as DSH01-9, and understand that moisture vapour emission from the slab must be checked before coating.
Why does epoxy need a topcoat?
Most epoxy coatings are aromatic and have poor UV resistance. In exterior service they will chalk, lose gloss and embrittle under sunlight. A polyurethane, acrylic or fluorocarbon topcoat protects the epoxy, holds the colour and extends the service life considerably. Inside a tank or a dry interior, epoxy can be the complete system.
How many coats of epoxy do I need?
It depends on the specification. A typical heavy-duty system is one zinc-rich primer at 60-80 µm, one high-build epoxy intermediate at 120-150 µm and one epoxy or polyurethane topcoat at 60-80 µm, giving 240-310 µm total. Light-duty interior work can be achieved with two coats at 80-100 µm each. Always work from the specified total DFT, not from a coat count.
Can epoxy coating be used for potable water tanks?
Yes, but only the grade that carries the certification. DSEH-701 Epoxy Drinking Water Tank Primer and Topcoat are FDA approved for potable water contact and are supplied as a matched system. Check the certificate covers your jurisdiction and the dry film thickness specified on the certificate.
How long does an epoxy coating last?
A correctly specified three-coat epoxy system on properly prepared steel gives 15-25 years in a typical industrial or marine atmosphere, and considerably longer in an enclosed or immersed environment. Poor surface preparation is the single biggest cause of early failure — blistering typically appears within 1-3 years.
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