deposited onto the substrate in further tests when further glass substrates were subjected to similar deposition conditions but with a longer pre treatment with titanium tetrachloride having being carried out which the inventors believe deposited a relatively thick layer of titanium oxide on the sico barrier layer either no aluminum was deposited or a semitransparent i e low reflective aluminium coating was deposited example 3 essentially repeated example 2 in passing a 4 mm sico coated float glass substrate through the dynamic laminar coater the glass temperature was however approximately 180 u00b0 c the glass was subjected to a pre treatment with titanium tetrachloride at a carrier speed of 388 mm min and during the deposition of the aluminium from the same alane adduct the carrier speed was 240 mm min the coating formed was a reflective aluminium coating over all the substrate when measured on the glass side the minimum transmission was 0 3 the maximum transmission was 3 0 the reflectance was 67 69 the brightness l was 85 85 and the colour coordinates a and b were 2 17 and 1 15 respectively these parameters may be compared to a standard silvered mirror having 89 42 as percentage reflectance brightness l 95 76 and colour coordinates a and b 2 18 and 1 95 respectively when measured from.