M770 topcoat – Sherwin Williams

The M770 water-based topseal is designed to be used over any of the Sherwin-Williams FX intumescent paints.

It dries quickly and achieves a gloss finish.

We especially recommend this topcoat for use in areas where solvent emissions are not desirable.

Also used as an essential decorative sealercoat for the FX product range to provide resistance to moisture.

Endorsements – BS476 Part 7 Surface Spread of Flame Material – for details of substrates/scheme consult the Customer Service Department.

Firetex M71V2, C137V2 or C237 may be used in place of M770 if circumstances require it. Either coating should be applied within 7 days for best performance.

If you require the product to be tinted, please contact our sales team with your desired RAL or BS colour code.

Application methods

M770 is highly versatile, as it can be applied by airless spray, conventional spray, brush or roller

It can be cleansed and thinned with water.

Before application, the application surface must be clean, dry and free from all surface contamination.

It has a theoretical coverage rate of 11.1m² per litre, so one 5L drum is sufficient for around 55.5m².

Dry Film Thickness (DFT) – 35 microns

Wet Film Thickness (WFT) – 90 microns

* This figure makes no allowance for surface profile, uneven application, overspray or losses in containers and equipment.
Film thickness will vary depending on actual use and specification.

Drying times

At 15ºC

To touch: 30 minutes
To handle: 5 hours
To recoat: 5 hours

At 23ºC

To touch: 15 minutes
To handle: 3 hours
To recoat: 3 hours

These figures are given as a guide only. Factors such as air movement and humidity must also be considered.

It can be self-overcoated indefinitely.

Spray and Airless Spray Information

Petrol Unit
Nozzle Size 0.38mm (15 thou)
Operating Pressure 140kg/cm² (2000 psi)

Petrol Unit
Nozzle Size 0.38mm (15 thou)
Operating Pressure 105kg/cm² (1500 psi)

The airless spray details given above are intended as a guide only. Details such as fluid hose length and diameter, paint temperature and job shape and size all have an effect on the spray tip size, angle and operating pressure chosen. Please ensure the operating pressure is as low as possible, consistent with satisfactory atomisation.  As conditions will vary from job to job, it is the applicators’ responsibility to ensure that the equipment in use has been set up to give the best results. Please contact us on 01752 690997 for technical advice.

Conventional Spray
Nozzle Size 1.27mm (50 thou)
Atomising Pressure 3.5kg/cm² (50 psi)
Fluid Pressure 0.7kg/cm² (10 psi)

These details are only a guide. Slight variations of pressure may provide atomisation in some circumstances according to the set up in use.
Atomising air pressure depends on the air cap in use and the fluid pressure depends on the length of line and direction of feed i.e. horizontal or vertical.

For more details, please contact us, or consult the technical data sheet in the tab above.