of a solution of dbtl at 10 in butyl acetate the viscosity is adjusted with 10 g of methoxy propanol acetate the resultant varnish is applied with a 100 u03bcm spiral applicator on a 0 7 mm thick degreased chromated aluminum plate the test piece is dried in an oven at 80 u00b0 c for 30 minutes which yields a 22 u03bcm thick dry film the film underwent without change 100 back and forth strokes with mek exhibited a persoz hardness of 207s measured according to nft 30016 and a specular gloss at 60 u00b0 of 62 measured according to astm d 523 85 the critical surface tension was 30 mn m the stain resistance results are represented in the following tables the ground base is prepared by dispersing for 30 minutes at 1 500 rpm 117 8 g of titanium dioxide with 181 4 g of the aforementioned copolymer solution and 20 g of methoxy propanol acetate to 59 6 of this white ground base are added 9 4 g of the aforementioned copolymer solution 19 2 g of a trimer of hexamethylene diisocyanate 1 8 g of a solution of dbtl at 10 in butyl acetate and 5 g of butyl acetate the resultant paint is applied with a 100 u03bcm spiral applicator to a 0 7 mm thick degreased chromated aluminum plate the test piece is dried in an oven at 80 u00b0 c for 30 minutes which yields a 22.