A coating failure rarely begins with the final coat. It usually starts earlier, when a system is selected without a clear picture of the substrate, the exposure conditions or the preparation that can realistically be achieved. This industrial coating specification guide helps maintenance teams, builders, facility managers and trade applicators set out a coating system that suits the job rather than relying on a product name alone.
A useful specification does more than nominate a paint colour and gloss level. It records what is being coated, what it has been exposed to, how it will be prepared, which coating layers are compatible, and the practical limits around application. Getting those details right reduces uncertainty before materials are ordered and work begins.
Start with the asset and its service conditions
The same steel frame can need very different protection depending on where it sits. Steel inside a dry warehouse is not exposed in the same way as handrails near the coast, processing equipment subject to regular washdown, or plant in an area with chemical splashes. A coating system needs to match the actual operating environment, not the assumed one.
Begin by recording the asset, its location and the existing surface. Is it bare mild steel, galvanised steel, aluminium, concrete, masonry, previously painted steel or a mix of substrates? Identify whether the area is indoors or outdoors, sheltered or fully exposed, and whether it experiences salt, humidity, UV, abrasion, chemicals, oils, heat or frequent cleaning.
Also consider how the asset is used. A decorative finish on a low-contact wall has different requirements from a coating on machinery guards, warehouse floors, tanks or structural steel. Where access for future maintenance is difficult, specifying a more thorough preparation and suitable coating system at the outset may be worthwhile. Where shutdown time is limited, application windows and cure requirements can be equally important.
Inspect the existing coating before specifying over it
Painting over an existing coating is often practical, but only when the old film is sound and compatible with the proposed system. Do not assume that a surface which looks intact is ready for another coat.
Inspect for rust, corrosion staining, chalking, peeling, blistering, cracking, under-film corrosion, impact damage and contamination. Check whether old coatings soften or react when tested in an inconspicuous area, following the relevant product guidance. If the existing coating is failing, applying a new topcoat over it will not correct the underlying problem.
The specification should state whether loose or defective coating must be removed, whether feathering is required at sound edges, and whether a test area is needed before the full project proceeds. This is especially useful where coating history is unknown, multiple previous systems are present, or maintenance work is being completed in stages.
Surface preparation is the foundation of the system
Preparation should be written as a clear requirement, not a vague instruction to “clean thoroughly”. The coating may be technically suitable, but it still needs a clean, dry and stable surface to perform as intended.
For steel, preparation may involve removing oil and grease, washing away salts and contaminants, mechanically removing rust and loose material, and creating a suitable surface profile where the selected primer requires it. The appropriate method depends on the asset, access, acceptable containment measures and the coating system. A hand-tool cleaned surface and an abrasive-blasted surface are not equivalent, so they should not be treated as interchangeable in the specification.
Concrete and masonry need their own assessment. New substrates must be adequately cured and dry in accordance with product instructions. Existing surfaces may require cleaning, removal of weak material, treatment of efflorescence, and repair of cracks or surface defects before coating. Moisture movement, hydrostatic pressure and contamination can all affect results, particularly in floors and below-ground areas.
Galvanised steel and aluminium can be challenging because they are smooth, may carry contaminants from manufacture or weathering, and often require a compatible primer or surface treatment. The specification should identify the substrate accurately rather than grouping all metal under one instruction.
Make preparation measurable
A practical specification gives the site team a way to check preparation before coating starts. This might include confirming that the surface is free from visible loose rust and peeling paint, dry, free of dust and grease, and prepared to the standard set out in the technical data sheet.
For larger or higher-risk work, document inspection points between stages. This creates an opportunity to address contamination, poor edge preparation or missed corrosion before it is sealed beneath subsequent coats.
Select each coat as part of a complete system
A coating specification should explain the job of each layer. The primer is commonly responsible for adhesion and substrate protection. Intermediate coats can build film thickness or contribute barrier protection. The topcoat provides the required finish and may contribute weathering, UV or chemical resistance, depending on the product.
Not every project needs three coats, and more coats are not automatically better. The correct system depends on exposure, substrate condition, desired appearance and maintenance expectations. A suitable industrial system may include a compatible primer and topcoat, while another situation may call for an epoxy-based system, a specialist sealer or a different approach entirely.
Compatibility matters at every stage. A high-performance topcoat cannot compensate for an unsuitable primer, and a primer cannot compensate for poor cleaning. Specify products that are designed to work together and follow the stated recoat windows, mixing instructions and thinning limits. If a substrate has an existing coating, confirm that the planned system is appropriate for recoating it.
Set film build, coverage and quantities realistically
Coverage figures are planning tools, not a substitute for measuring the job. Surface roughness, profile, porosity, application method, overspray, complex geometry and wastage can all change the amount of coating required.
Your specification should state the number of coats and the required dry film thickness where it is nominated in the relevant technical documentation. Wet film thickness may also be useful during application because it gives the applicator a practical check while the coating is still wet. Applying a coat too thin can reduce protection and hiding, while applying it too heavily can lead to slow drying, runs, solvent retention or other film issues.
Measure the area carefully and allow for structural members, edges, bolts, welds and awkward sections that increase surface area. On steelwork, edges and welds deserve particular attention because they are common weak points for coating coverage. Where the system calls for stripe coating, make that a stated requirement rather than an assumption.
Include application conditions, not just product names
Coatings are affected by site conditions. Temperature, surface temperature, relative humidity, ventilation, condensation risk and rain can all influence application and curing. A specification should require application within the limits listed on the relevant technical data sheet and safety data sheet.
This is particularly important outdoors in Western Australian conditions, where hot surfaces, afternoon winds and changing weather can affect application. In enclosed spaces, ventilation and safe handling arrangements need planning before work starts. Do not apply coating to a damp surface or one likely to experience condensation before the film has reached the required stage of cure.
State the approved application method, whether brush, roller, conventional spray or airless spray, based on the product instructions and the shape of the work. Methods may be mixed within one project, such as brush application for edges and bolts with spray application on broad steel surfaces, provided the system and required film build are maintained.
Build inspection and maintenance into the specification
The final section should define how the completed work will be checked. Confirm colour and finish where relevant, complete coverage, dry film requirements if specified, coating continuity at edges and welds, and the absence of obvious defects such as misses, runs, pinholes or contamination.
Retain batch details, product names, application dates and any records of preparation or inspections. These notes are useful when planning future maintenance and investigating localised damage. They also make it easier to specify compatible touch-up work later.
Maintenance should be based on regular inspection rather than waiting for widespread failure. Cleaning off deposits, addressing impact damage promptly and treating early corrosion can help preserve the wider coating system. The timing will depend on exposure and use, so a coastal industrial site may need more frequent attention than a dry internal area.
Turn the specification into a workable site document
The best industrial coating specification is specific enough to guide purchasing, preparation and application, but practical enough for the people doing the work. Include the substrate, exposure, preparation standard, nominated coating layers, number of coats, application conditions, recoat requirements, inspection points and the technical documents to be followed.
If the surface, existing coating or exposure is uncertain, resolve that before selecting materials. BG Coatings can provide product information, technical data sheets and practical guidance to help match an appropriate coating system to the job. A clear specification gives every person involved the same starting point – and that is where a more dependable finish begins.
