There is a difference between grit blasting and Rustibus. Rustibus will not create same rugged, angular profile (microns/mils) as grit. Rustibus is mechanical de-scaling with a surface cleanliness result of ST3+/SSPC-SP11+ . But because implicit definitions of "roughness" and profile form vary between methods, numerical profiles determined using different techniques (replica tape, interferometer, confocal microscope, analogue stylus, digital stylus) may yield different values. Always specify the technique used.
Most of our customers who used to grit blast now only use Rustibus, being sufficient for most purposes. However, should a ‘Blasted’ profile or for example SA3 blast class be needed, one will need to grit blast after the use of Rustibus to get that specific final result. By combining Rustibus with grit/sand blasting one will normally save 80-85% grit/sand being a huge cost saving and more environmentally friendly.
It must also be remembered that while good surface profile is important to increase surface area and provide a good anchor pattern for coatings to lock on to; it can be just as disastrous to have excessive profile height, causing premature rusting and coating failures. Bear in mind that more profile means more paint to cover the surface.
There are two important rules of thumb when it comes to profile.
1. The profile height shouldn’t exceed the primer coat dry film thickness (DFT)
2. The profile height should not be greater than 1/3 the total coating system DFT