as per variant a the samples were then dried for 1 hour at 70 u00b0 c and powdercoated with a polyester based powder coat in this case akzo nobel mn204e the samples were scribed and testing was performed which involved daily cycles of 15 minute immersion in 5 nacl solution drying and 20 hour exposure to 90 relative humidity after 10 cycles of this test variant a showed signs of corrosion at the edges and in the vicinity of the scribe line after 30 cycles much of the powder coat had fallen off at the edges and significant blistering and corrosion creep up to 8 mm from the scribe line had occurred after 40 cycles of the test variant b showed no sign of corrosion at the edges but some blistering and corrosion creep were visible up to 3 mm from the scribe line on variants c and d the corrosion creep was maximum 1 mm from the scribe line aluminium 1050 architectural components requiring pre treatment to ensure durability of polyester powdercoat in accelerated testing to satisfy architectural lifetime standards for a powdercoat 25 year guarantee the aluminium parts were all de greased for two minutes at 55 u00b0 c by immersion in an alkaline solution including an anionic surfactant such as sodium or potassium tartrate in this case chemetall u201c gardoclean t5378 u201d at 33 g l disodium tetraborate 10 25 tetrasodium pyrophosphate 10 25 fatty alcohol polyglycol ether 2 50 10 and anionic surfactant at 1 2 5 and rinsed for two minutes in de ionised water the parts were then treated according to several different pre treatment methods prior to rinsing drying and powdercoating some a b and c typical of.