S708 Intumescent Basecoat is a single pack, very low VOC waterborne intumescent coating for fire protection of internal and semi-exposed structural steelwork. It is suitable for universal and hollow sections and can be applied to a smooth matt finish. For a more decorative finish a compatible topseal is available.
Nullifire S708 has been certified to provide up to 60 minutes fire rating.
(BS 476:Part 21 1987)
Ensure then surface is clean, undamaged, dry, suitably primed* and free from grease or other materials that may affect adhesion.
Special Note *
When selecting primers, please note thermoplastic primers and chlorinated rubber coatings may cause adhesion problems and should be avoided. Recommended Primers are Nullifire PM015 and PM018.
Galvanised steelwork should be prepared by an application of T-wash or mordant solution followed by a compatible primer.
If a Zinc Rich Primer is used, it is advisable to seal this with a suitable holding coat to the avoid the formation of surface salts that may build up on the steel.
These salts, if not adequately removed, may cause adhesion problems for any subsequent coating applied.
Ensure air and steel temperatures are above 5°C and below 35°C.
Relative humidity should be below 80% and the steel surface temperature should be a minimum of 3°C above the dew point.
Ensure the steel is dry and free from contact with rain or condensation during application.
If the basecoat is allowed to get wet during the drying phase it is likely to be damaged – surface patterning, blistering and wrinkling may occur.
Nullifire S708 is supplied ready for use. Do not thin.
Airless spray equipment is recommended. Typical equipment settings would be:
Operating Pressure: Min 2500 - 3000 psi (175 - 210 kg/cm²)
Tip Size: 17 – 23 thou
Fan Angle: 20° – 40°
Hose Diameter: 10 mm (3/8”) (internal diameter)
Hose Length: Max. 60 metres.
Inline filters should not normally be used.
Nullifire S707 can be applied up to a maximum wet film thickness (WFT) of 1.2 mm in a single spray coat comprising of several quick passes.
Build up the film thickness to achieve the loading required in several passes.
Brush and Roller application
For brush application use a “laying on” technique to avoid heavy brush marking.
Maximum wet film per coat when applied using a brush or roller is 1.0 mm.
A short pile roller will produce a light textured finish.
During application, measure the wet film thickness (WFT) frequently with a WFT gauge to ensure the correct thickness is being applied.
Drying time will be dependent upon temperature, air movement, humidity, method of application and the thickness of the coating.
Typically a WFT of 1.2mm at 20° C will dry in 9-12 hours.
High humidity and low air movement or low steel temperatures can result in condensation on the steelwork causing prolonged drying times and possibly poor basecoat adhesion.
Once the basecoat is dry a number of protective and decorative topseals are available. these are Nullifire TS134 (Acrylic) TS815 (modified Acrylic) and TS816 (Waterbased Acrylic)
Cleaning of Equipment.
Pump, mixer and hose should be cleaned with water only.
Please observe the Safety Data information and for any questions please do not hesitate to call us.