of only 40 obtained without the use of the shielding member 9 similarly using a triangular section shielding member 9 whose base is 25 mm wide and which has an included angle of 60 u00b0 at its apex and is suspended with its base 25 mm below the lower edge of glass sheets 2 3 mm thick a yield of 88 was obtained when quenching the glass sheets having a lower edge temperature of about 640 u00b0 c in a fluidised bed of u03b3 alumina whose temperature was in the range 50 u00b0 to 80 u00b0 c the yield obtained without use of the shielding member 9 was only 8 glass sheets 3 mm thick heated to various temperatures were quenched in a fluidised bed of u03b3 alumina without the use of a shielding member and also using a triangular section shielding member whose base was 51 mm wide and was spaced 51 mm below the lower edge of the glass sheets the fluidising gas velocity used was 11 mm s the results are set out in table iv table iv______________________________________temperature oflower edge ofglass sheet yield u00b0 c no shielding member with shielding member______________________________________615 620 0 50620 625 25 80625 630 42 100630 635 77 100______________________________________ table iv shows that the shielding member can be used not only to increase yield figures at a given temperature but can also maintain the level of yield at lower glass temperatures by using lower glass temperatures the problem of loss of overall glass shape is alleviated a clear indication.