______________________________________magnetite tin oxide coatings______________________________________ a i top coating 14 u03b1 u03b5 01 solution from example 1 a ii ii bottom coating 12 fe sub 3 o sub 4 88 19 b i top coating 14 fe sub 3 o sub 4 ii bottom coating 12 01 solution from example 1 a ii 87 34______________________________________ to 7 0 ml of sncl 4 solution 1 40 gm sncl 4 5h 2 o ml in 1 5 hcl was added 1 5 ml of 24 6 hf 49 2 hf diluted 1 1 in propanol 2 the solution was sprayed on a plate preheated to 650 u00b0 c the resulting film produces an emissivity u03b5 of 0 11 thus the coating of this example 3 may be substituted for top coating 14 in examples 1 and 2 in composite selective absorber films such as the one described in examples 1 and 2 the overall performance is improved as the emissivity u03b5 of the top coating 14 is decreased thus substitution of tin doped indium oxide for antimony doped tin oxide will improve the selective absorption efficiency of the composite coating however the much higher cost of incl 3 as compared to sncl 4 mitigates.