I rarely had any problem with blue grit apart from it takes time to apply correctly. I was looking for a cheaper alternative as customer are getting budget sensitive and found Bostik/Cementone Primer seem to be getting consistent praise about coverage here. However, their technical data sheet says the coverage is 3-4m2/litre whereas blue grit technical data sheet says coverage is 4.5m2/litre which is more than bostik? Bostik is also more expansive too? am I missing something here?