Iridite ?

[Ultralights]

Having fixed mr Boeings creations for 10 yrs now, from a sheetmatal and composite structures perspective, can someone plaese tell me what the Iriditing process is suppost to do? i cannot find it in any manuals, and iridited parts corrode just as quick as untreated parts. is there any other reason for this except to stain your overalls yellow? this stuff cant be good for you

[Ali Crom]

Ultralights , the application of Iridite ( more commonly known as Alodine or Alocrom ) is a chemical cromate conversion process usually applied by brush & paper towel or immersion to provide a corrosion resistant coating to aluminium parts & to provide a base for subsequent protective paint finishes .In my experience , parts which have been previously reworked & coated using the process have on occasion corroded again ( assuming all corrosion was removed in the first place ) . This may be due to the enviroment in which the material is subjected to i.e prolonged contact with corrosive substances ( urine , coffee etc. ), blocked drain holes in stringer/frames , damage to the protective paint finish - around fastener holes in particular , the list is endless . As far as finding info on the process I think ch.51 in the s.r.m.& ch.20 s.p.m. gives details on how & what types to use ( Alodine 600/1000/1200 ). With reference to safety I don't know of any chemical used within the aircraft maintenance game that isn't hazardous so I would err on the side of caution & always wear protective gloves when handling this stuff . Hope this is of some use .

[This message has been edited by Ali Crom (edited 23 December 2000).]