Sherwin-Williams Firetex FX1003 Intumescent Paint

Availability: In Stock

£308.17 inc. VAT: £369.80

Sherwin-Williams FX1003 is a solvent-based intumescent paint designed for structural steelwork, including RSJs, square hollow sections, channels, angles, etc.

It can provide up to 120 minutes fire resistance. It has been Certifire approved – Certificate CF5077.

It often provides highly competitive loadings against other intumescent paints.

Firetex FX1003 only comes in 20L drums.

For a free specification, please call us on 01752 690997, or send back the steel paint enquiry form in the data sheets tab below. Our email address is

Sherwin Williams FX1003 is a solvent-based intumescent coating designed for structural steelwork.

It provides up to 120 minutes resistance, depending on the loading you put onto your steels.

Certifire approved – Certificate CF5077.

Highly competitive loadings.

Easy application properties. This one-pack intumescent can be applied by either brush or airless sprayer. Please follow the application instructions in the data sheets tab above.


Firetex FX1003 can be exposed to the weather for up to 6 months provided that the specific use does not lead to ponding water.

For external exposed steelwork (up to a C4 environment) and severe internal environments Acrolon C137V2 or Acrolon C237 must be used as a topcoat.

In a C2 Internal environment, the Sherwin-Williams M71V2 topcoat would be needed.

No topseal is required in an internal C1 situation. However, where a finish colour has been specified we can supply a suitable topseal available in a wide range of BS4800 or RAL colours. Please call us to order coloured topcoats.

Steel Preparation & Primers:

A primer is used as a preparatory coating put on the steel before applying FX1003 and acts to provide corrosion protection. Without a compatible primer being applied at the correct thickness, lots of issues could arise. The most common issue surrounding surface preparation is for rust spots to appear through the intumescent paint after its application. Priming also ensures better adhesion of the intumescent paint to the surface, increases its durability, and provides additional protection for the material being painted.

We recommend for all customers to send over technical data sheets of their primers, so we can run a compatibility check between the primer and intumescent coating.

If your steel is rusty, the rust must be removed adequately before applying the primer. Details on surface preparation can be found in the technical data sheet of most primers.

Intumescent Paint Guidance Notes:

The thickness of FX1003 is dependent on the steel section used and the protection time required. We can calculate the required film thicknesses for your project. Please contact us on 01752 690997 for a free quote.

With all steel intumescent paints, a factor called HP/A (heated perimeter divided by cross sectional area) is used. NB: HP/A is generally used with British testing and A/V in European testing, however, the principles are the same and both are accepted methods of calculating the steel section factor.

The rate increase in temperature of a steel cross-section is determined by the ratio of the heated surface area (A) to the Volume (V). This ratio A/V, has units of m-1 and is known as the “Section Factor”. Steel members with low Section Factors will heat up more slowly. A steel section with a large surface area (A) will receive more heat than one with a smaller surface area. Also, the greater the volume (V) of the section, the greater the heat sink. Therefore, a small thick section will be slower to increase in temperature than a large thin one. The Section Factor (A/V or HP/A) is thus a measure of the rate at which a section will heat up in a fire. The higher the value of the Section Factor the greater the protection thickness required.



The information displayed about the products on this website is to be used for guidance ONLY. We advise that all customers contact our technical department to obtain a free no obligation specification and quotation before purchasing goods directly from the website.

Products purchased directly from our website without specification will NOT qualify for certification.

Please be aware that any negligence caused by failure to obtain the relevant advice, or availment of our specification and estimation service, will absolve International Passive Fire Ltd from any liability should Passive Fire Protection Products prepared, or used, by the purchaser, or any other parties, result in damage to property or human life, or for any monetary costs incurred due to incorrect usage.


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Data Sheets

  • What is the spreading rate of this paint?
    With all intumescent paints for steel, there is no fixed spreading rate. This is because the amount needed varies depending on the size and shape of your steels.For a full specification, please email us the steel paint enquiry form, which can be found in the data sheets tab. Email address:
  • How much does intumescent paint expand?
    Intumescent paint expands to 50 times its dry film thickness. It is important that there is enough room around your steels to accommodate for this expansion gap.
Fire Rating

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Internal or External Use


Coating Type