This guarantees that the ratio of solvents to air is low due to the fresh air intake. This fresh air
intake is across the burners, therefore it is heated before it enters the oven, thus reducing
significantly any chance of condensate buildup, which normally occurs when cold air enters the oven through the work openings. The neutral oven keeps the oven slightly pressurized, again, to prevent cold air from coming through the work openings. Since the solvent-to-air ratio is low,the air that is exhausted through the exhaust stack is much cleaner than the air that is exhausted when the fresh air ports are closed.