a demister apparatus for machine tools having an enclosure booth for confining mist in which a varying outflow of air is drawn from the booth and directed to a remote demister apparatus from a minimum when the access doors to the enclosure are closed to a maximum when one or more of the doors are opened . the air flow may also be varied with the number of machine tools in operation as well with the state of filters in the remote demister apparatus . a cyclonic separator is also provided adjacent to the booth which functions well in a vertical up flow mode over a range of air outflow rates of flow .