Before any primer or intumescent coating is applied, the substrate must be free from contaminants that compromise adhesion and fire-rating performance. Cleaning and degreasing form the essential first step in every compliant fire-protection system where substrates and existing coatings remain sound.
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.
Watch Explainer Video
When Cleaning Is Required — Not Stripping
Preparing Sound Substrates Without Unnecessary Removal
Structural steel and timber elements with intact, well-adhered coatings do not always require abrasive removal. Where there is no corrosion, mill scale or coating failure, targeted cleaning and degreasing restores surface cleanliness efficiently without the cost, disruption or programme impact of blasting or mechanical removal.
This approach is commonly used prior to primer application on refurbishment projects, maintenance works or phased fire-protection upgrades.
Contaminants That Must Be Removed
Dust, Oils, Grease and Atmospheric Deposits
Industrial and urban environments deposit contaminants that interfere with coating adhesion. Oils, grease, dust, salt spray and atmospheric pollution weaken the bond between substrate and fire-protection systems.
If not removed, these contaminants can lead to adhesion failure, uneven coating build and compromised fire performance. Thorough cleaning is therefore mandatory before any primer or intumescent application.
Cleaning Methods
Selecting the Correct Cleaning Technique
Cleaning methods are selected based on the type and level of contamination present, as well as substrate condition. Each method removes specific contaminants while preserving sound coatings and preparing the surface for fire-protection application.
Solvent Wiping
Used to remove light oils, grease and surface contamination from sound coatings and bare substrates. Commonly applied prior to primer application on steel and timber.
Pressure Washing
High-pressure water cleaning removes dust, loose debris and salt deposits from exposed surfaces. Suitable where abrasive blasting would be excessive and substrates remain sound.
Detergent Cleaning
Alkaline or acidic detergents dissolve stubborn grease, oils and atmospheric contamination. Surfaces are thoroughly rinsed to prevent residue that could interfere with coating adhesion.
Where Cleaning Is Not Sufficient
Chalking and Weak Coatings Must Be Removed
Cleaning alone is not suitable where existing coatings are failing, powdering or chalked. Weak or degraded paint layers cannot support new fire-protection systems and must be removed back to a sound substrate using abrasion or blasting before cleaning and primer application.
Clean Surfaces Enable Reliable System Performance
Primers and intumescent coatings rely on clean, stable surfaces to bond correctly. Contamination or weak coatings prevent adhesion, allow moisture ingress and compromise fire performance.
Proper cleaning supports uniform coating build, reliable Wet Film Thickness control and long-term system durability in line with tested fire-resistance performance.
Standards & Manufacturer Requirements
Cleanliness Is a Specification Requirement
All intumescent coating and primer manufacturers specify minimum cleanliness requirements prior to application. These requirements are mandatory for warranty validity, fire-rating certification and compliance with BS 476 and EN 13381 testing protocols.
Steel substrates must be clean, dry and free from oils, grease and salts
Timber surfaces must be free of dust, loose material and surface contamination
Prepared surfaces must meet manufacturer and ISO cleanliness standards for adhesion
Myles Howson
Managing Director
Thank you! Your submission has been received. We’ll aim to reply within 24–48h.
Oops! Something went wrong while submitting the form. Please try again.
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.
“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
eyebrow
"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
eyebrow
"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
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.
.png)