Services
Surface Preparation
Abrasive Blasting

Abrasive Blasting to SA 2.5 (Near-White Metal Finish)

Abrasive blasting to SA 2.5 removes rust, mill scale and failed coatings to expose clean steel substrate. This preparation creates the mechanical key required for intumescent coating adhesion and verified fire-rating performance. For many intumescent systems, SA 2.5 preparation is a mandatory requirement for manufacturer warranty and building control approval.
Video Explainer

Surface Preparation Methods for Structural Steel

This short video explains the different surface preparation methods we use, when each one is specified, and why correct preparation is critical before any intumescent coating is applied.
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Two large vertical steel columns installed on a concrete floor with a yellow Werner ladder nearby in a construction site.
Understanding the SA 2.5 Standard

What “Near-White Metal” Means

SA 2.5 is defined under ISO 8501-1 as a near-white metal finish where no more than 5% of the surface shows light staining, shadows or residual marks when viewed under standard lighting conditions. This benchmark ensures the steel is sufficiently clean to support long-term adhesion and reliable intumescent performance under fire exposure.
When SA 2.5?

When SA 2.5 Preparation Is Required

Abrasive blasting to SA 2.5 is specified where surface condition or risk level demands full removal of contaminants.
Heavy Corrosion
Extensive rust and corrosion products require complete abrasive removal to restore surface integrity.
Failed Coatings
Delaminated, peeling or incompatible coatings must be stripped back to bare steel to prevent adhesion failure.
Deep Corrosion Pitting
Significant surface loss requires uniform blast cleaning to create a consistent profile across all steel elements.
Mill Scale
Factory-formed oxide layers inhibit adhesion and must be fully removed for compliant coating application.
Close-up of rusty, reddish-brown and orange oxidized steel surface with signs of corrosion and a silver weld line.
Adhesion & Mechanical Key

Why Surface Profile Matters

Abrasive blasting creates a controlled surface profile that allows intumescent coatings to bond mechanically to the steel. This mechanical key prevents delamination under thermal stress and supports long-term system durability. Without the correct profile, coatings can fail prematurely regardless of product quality or applied thickness.
Blasting Equipment & Media

Consistent Preparation Using Industrial Systems

SA 2.5 preparation is carried out using industrial-grade blasting equipment to maintain consistent pressure, coverage and surface profile.
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01
High-Capacity Air Supply
Compressors deliver sustained air volume and pressure throughout the blast cycle to ensure uniform cleaning.
02
Abrasive Media Selection
Garnet and steel grit are selected based on surface condition and project requirements. Garnet provides sharp cutting action, while steel grit offers durability and efficiency for large-scale works.
Verification of SA 2.5 Compliance; Inspection Before Coating Application
SA 2.5 compliance is verified through visual comparison against ISO 8501-1 standards and supported by dust and cleanliness checks where required. Verification confirms the substrate is suitable before any primer or intumescent coating is applied, preventing costly failures later in the process.
White steel support columns installed in an unfinished basement or industrial space with concrete floor and block walls.
Hand in blue glove holding a brown gauge tool against a white textured surface in a construction setting.
Impact on Fire-Protection Performance

Preparation Enables Accurate WFT Control

A clean SA 2.5 surface allows intumescent coatings to be applied evenly and measured accurately. This directly supports the achievement of specified Wet Film Thickness targets and ensures the installed system matches tested fire-performance data.

  • Eliminates voids and uneven coating build

  • Enables consistent WFT measurement across steel sections

  • Reduces risk of premature delamination and corrosion

Empty indoor construction site with concrete floor, white pillars, yellow ladder, ventilation duct, and construction tools scattered around.
Containment & Site Control

Managing Dust & Environmental Impact

Abrasive blasting generates dust and debris and must be carried out within controlled containment. Enclosures, shrouded equipment and vacuum systems are used to limit airborne particles, protect surrounding areas and maintain safe working conditions on live sites.
Benefits and Practical Considerations

Why SA 2.5 Is the Gold Standard

Advantages

SA 2.5 preparation guarantees manufacturer compliance, supports certification and delivers maximum system durability under thermal and environmental stress.

Limitations

Blasting requires specialist equipment, trained operators and controlled conditions. Noise, weather sensitivity, waste disposal and programme duration must be considered during planning.

When SA 2.5 Is Non-Negotiable
Intumescent coating manufacturers frequently specify SA 2.5 preparation as a mandatory requirement for warranty and fire-rating certification. Fire engineers and building control bodies require documented evidence of SA 2.5 preparation before approving fire-protection systems for higher-risk structural steel applications.
Close-up of a rusty metal surface with peeling paint and corrosion under a concrete structure.
Man wearing a white protective suit, yellow safety vest, and gray hard hat taking a mirror selfie in a restroom with blue stalls and a soap dispenser.
Myles Howson
Managing Director
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Other Surface Preparation Methods

Different substrate conditions require different preparation techniques. We assess corrosion levels, existing coatings and site constraints to specify the most appropriate method for compliance and long-term performance.
Comparison of two structural steel beams in a construction site, one heavily rusted red beam above a cleaned dark gray beam, with a yellow ladder and orange equipment below.
Surface Prep
Dry Ice Blasting
Non-abrasive surface preparation for removing contamination, failing coatings and residues without damaging the substrate. Particularly suited to sensitive environments and refurbishment works.
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Close-up of rust and mill scale corrosion on structural steel surface.
Surface Prep
Mechanical Abrasion
Controlled preparation using hand and mechanical tools where full blasting is not required. Often used for localised preparation, edge treatment and touch-up areas.
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Worker in a yellow safety vest and blue gloves preparing a large steel column inside a building under construction.
Surface Prep
Cleaning & Degreasing
Removal of surface contaminants such as oils, dirt and residues to ensure compatibility and adhesion of fire-protection systems on new or previously coated steel.
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From the founder

“After a decade in the protective coatings industry, I built FireCoatings to deliver compliant fire protection without unnecessary noise — just clear documentation, a controlled application process, and professional site practice.”

Myles Howson
Managing Director
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"Thank you Myles and team for all your hard work on this one. It wasn't easy working around the schedule but you got it done without causing any further issues. It was a pleasure to work with you."
Chris
Project Manager, Millcroft Services
Interior view of a construction site featuring steel beams and columns painted with white protective coating and temporary support props.
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"NuColour worked efficiently around our programme and delivered a on time at late notice. The team were organised, flexible, and professional throughout the works."
Ciprian
Site Manager, Principal Contractor – GEMCO
Close-up of a bright yellow structural steel column with rivets installed on a construction site indoors.
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location index

Areas We Cover

NuColour delivers specialist contracting services across London and the surrounding regions. Our teams operate throughout the South East, supporting commercial, industrial, and large-scale refurbishment projects with consistent standards, professional oversight, and experienced delivery.
Intumescent Coatings Acton, London.
Intumescent Coatings Archway, London.
Intumescent Coatings Balham, London.
Intumescent Coatings Barking, London.
Intumescent Coatings Battersea, London.
Intumescent Coatings Beckenham, London.
Intumescent Coatings Belvedere, London.
Intumescent Coatings Bethnal Green, London.
Intumescent Coatings Brentford, London.
Intumescent Coatings Brixton, London.
Intumescent Coatings Camberwell, London.
Intumescent Coatings Camden, London.
Intumescent Coatings Canary Wharf, London.
Intumescent Coatings Chelsea, London.
Intumescent Coatings Chigwell, London.
Intumescent Coatings Chiswick, London.
Intumescent Coatings City of London, London.
Intumescent Coatings Clapham, London.
Intumescent Coatings Covent Garden, London.
Intumescent Coatings Dagenham, London.
Intumescent Coatings Dalston, London.
Intumescent Coatings Deptford, London.
Intumescent Coatings East Ham, London.
Intumescent Coatings Edgware, London.
Intumescent Coatings Epping, London.
Intumescent Coatings Erith, London.
Intumescent Coatings Finchley, London.
Intumescent Coatings Finsbury Park, London.
Intumescent Coatings Fitzrovia, London.
Intumescent Coatings Fulham, London.
Intumescent Coatings Golders Green, London.
Intumescent Coatings Hackney, London.
Intumescent Coatings Hammersmith, London.
Intumescent Coatings Hampstead, London.
Intumescent Coatings Harefield, London.
Intumescent Coatings Haringey, London.
Intumescent Coatings Harrow, London.
Intumescent Coatings Havering, London.
Intumescent Coatings Hayes, London.
Intumescent Coatings Highgate, London.
Intumescent Coatings Hillingdon, London.
Intumescent Coatings Holloway, London.
Intumescent Coatings Hornchurch, London.
Intumescent Coatings Hounslow, London.
Intumescent Coatings Hoxton, London.
Intumescent Coatings Ilford, London.
Intumescent Coatings Islington, London.
Intumescent Coatings Kensington, London.
Intumescent Coatings Kensington and Chelsea, London.
Intumescent Coatings Kilburn, London.
Intumescent Coatings Kingston upon Thames, London.
Intumescent Coatings Lambeth, London.
Intumescent Coatings Lewisham, London.
Intumescent Coatings Leyton, London.
Intumescent Coatings Marylebone, London.
Intumescent Coatings Mayfair, London.
Intumescent Coatings Merton, London.
Intumescent Coatings Mill Hill, London.
Intumescent Coatings Mitcham, London.
Intumescent Coatings New Malden, London.
Intumescent Coatings Newham, London.
Intumescent Coatings Northolt, London.
Intumescent Coatings Notting Hill, London.
Intumescent Coatings Orpington, London.
Intumescent Coatings Palmers Green, London.
Intumescent Coatings Peckham, London.
Intumescent Coatings Penge, London.
Intumescent Coatings Plaistow, London.
Intumescent Coatings Poplar, London.
Intumescent Coatings Rainham, London.
Intumescent Coatings Redbridge, London.
Intumescent Coatings Richmond, London.
Intumescent Coatings Richmond upon Thames, London.
Intumescent Coatings Romford, London.
Intumescent Coatings Ruislip, London.
Intumescent Coatings Shepherd's Bush, London.
Intumescent Coatings Shoreditch, London.
Intumescent Coatings Sidcup, London.
Intumescent Coatings Soho, London.
Intumescent Coatings Southgate, London.
Intumescent Coatings Southwark, London.
Intumescent Coatings Staines-upon-Thames, London.
Intumescent Coatings Stockwell, London.
Intumescent Coatings Stratford, London.
Intumescent Coatings Streatham, London.
Intumescent Coatings Surbiton, London.
Intumescent Coatings Sutton, London.
Intumescent Coatings Tooting, London.
Intumescent Coatings Tottenham, London.
Intumescent Coatings Tower Hamlets, London.
Intumescent Coatings Twickenham, London.
Intumescent Coatings Uxbridge, London.
Intumescent Coatings Waltham Forest, London.
Intumescent Coatings Walthamstow, London.
Intumescent Coatings Wandsworth, London.
Intumescent Coatings Wembley, London.
Intumescent Coatings West Ham, London.
Intumescent Coatings Westminster, London.
Intumescent Coatings Wimbledon, London.
Intumescent Coatings Wood Green, London.
Intumescent Coatings Billericay, Essex.
Intumescent Coatings Basildon, Essex.
Intumescent Coatings Braintree, Essex.
Intumescent Coatings Brentwood, Essex.
Intumescent Coatings Chelmsford, Essex.
Intumescent Coatings Colchester, Essex.
Intumescent Coatings Clacton-on-Sea, Essex.
Intumescent Coatings Danbury, Essex.
Intumescent Coatings Grays, Essex.
Intumescent Coatings Harlow, Essex.
Intumescent Coatings Hockley, Essex.
Intumescent Coatings Maldon, Essex.
Intumescent Coatings Loughton, Essex.
Intumescent Coatings Rayleigh, Essex.
Intumescent Coatings Rochford, Essex.
Intumescent Coatings Southend-on-Sea, Essex.
Intumescent Coatings South Woodham Ferrers, Essex.
Intumescent Coatings Tilbury, Essex.
Intumescent Coatings Wickford, Essex.
Intumescent Coatings Witham, Essex.
Intumescent Coatings Bishop's Stortford, Hertfordshire.
Intumescent Coatings Cheshunt, Hertfordshire.
Intumescent Coatings Hatfield, Hertfordshire.
Intumescent Coatings Harpenden, Hertfordshire.
Intumescent Coatings Hertford, Hertfordshire.
Intumescent Coatings Hemel Hempstead, Hertfordshire.
Intumescent Coatings Hitchin, Hertfordshire.
Intumescent Coatings Radlett, Hertfordshire.
Intumescent Coatings Rickmansworth, Hertfordshire.
Intumescent Coatings St Albans, Hertfordshire.
Intumescent Coatings Stevenage, Hertfordshire.
Intumescent Coatings Welwyn Garden City, Hertfordshire.
Intumescent Coatings Watford, Hertfordshire.
Intumescent Coatings Ware, Hertfordshire.
Intumescent Coatings Ashford, Kent.
Intumescent Coatings Canterbury, Kent.
Intumescent Coatings Chatham, Kent.
Intumescent Coatings Deal, Kent.
Intumescent Coatings Dartford, Kent.
Intumescent Coatings Dover, Kent.
Intumescent Coatings Folkestone, Kent.
Intumescent Coatings Gravesend, Kent.
Intumescent Coatings Gillingham, Kent.
Intumescent Coatings Herne Bay, Kent.
Intumescent Coatings Maidstone, Kent.
Intumescent Coatings Margate, Kent.
Intumescent Coatings Northfleet, Kent.
Intumescent Coatings Ramsgate, Kent.
Intumescent Coatings Royal Tunbridge Wells, Kent.
Intumescent Coatings Sevenoaks, Kent.
Intumescent Coatings Sittingbourne, Kent.
Intumescent Coatings Tonbridge, Kent.
Intumescent Coatings Whitstable, Kent.
Intumescent Coatings Caterham, Surrey.
Intumescent Coatings Camberley, Surrey.
Intumescent Coatings Chertsey, Surrey.
Intumescent Coatings Esher, Surrey.
Intumescent Coatings Epsom, Surrey.
Intumescent Coatings Ewell, Surrey.
Intumescent Coatings Farnham, Surrey.
Intumescent Coatings Godalming, Surrey.
Intumescent Coatings Guildford, Surrey.
Intumescent Coatings Leatherhead, Surrey.
Intumescent Coatings Redhill, Surrey.
Intumescent Coatings Reigate, Surrey.
Intumescent Coatings Walton-on-Thames, Surrey.
Intumescent Coatings Weybridge, Surrey.
Intumescent Coatings Woking, Surrey.
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