Abstract: The invention relates to a method for manufacturing a first ventilation zone in a first aerosol-generating article and a second ventilation zone in a second aerosol-generating article, comprising the method steps: A) providing a first aerosol-generating article, B) forming first perforations in the first aerosol-generating article, thereby creating a first ventilation zone, C) determining the first air infusion value for the first aerosol-generating article, the air infusion value being determined by the equation (Pin?Pout)·100%/Pin, wherein Pin is the air pressure applied at the first end face of the article and Pout is the air pressure detected at the second end face of the article, D) comparing said first air infusion value to a reference value, E) providing the second aerosol-generating article and forming second perforations in the second aerosol-generating article, thereby creating the second ventilation zone, wherein a size of the second perforations is adjusted based on the comparison between the dete

Abstract: The conventional operation of a cokeless cupola furnace has a requirement for a low volume of slag to be produced, because of the fact that there is no ash from coke to remove from the charge, and the fact that flux added to the charge to form slag eats away at the furnace lining, and at the bed of refractory spheres. Running the furnace at low slag volumes makes the slag thick and can cause blockage of the slagging and tapping box. The invention adds more flux materials than is conventional, preferably including silica in the form of broken bottles, so as to deliberately increase the volume of slag, improving the flow. Care must be taken not to add too much slag-forming materials.