14 whereas the housing formed of lower shell 22 and upper plate 24 is rigidly mounted to the rotary chuck body 12 therefore the frame 29 and thus also the lamps 21 23 25 that it carries are mounted for rotation relative to the surrounding housing formed of components 22 24 as will be described in greater detail below referring now to fig2 it can be seen that the wafer w is now supported by the ends of pins 16 projecting through the openings or notches 17 in the heating assembly 20 the wafer w is centered on the heating assembly 20 which in turn is centered on the axis of rotation of the underlying spin chuck it will be appreciated that the spin chuck 10 is therefore designed to hold a wafer w of a specified diameter in the embodiments described herein that diameter is 300 mm which is a common diameter of silicon wafer at present however the apparatus may of course be designed to hold disc shaped articles of other diameters such as 200 mm and 450 mm in the plan view of fig2 it can be seen that each of the three heating elements 21 23 25 in this embodiment is a continuous curved tubular element moreover while these heating elements generally follow a circular arc and while all three heating elements are preferably substantially.