Usage of dye penetrant crack detection

[Bhigdog]

I think i,m going to have to look for cracks in one of my corvette heads. I,m familiar with magnaflux and the mechanics at the hangar used a dye penetrant on aluminum. 

I,m looking for info on using a dye penetrant on cast iron. Good bad or indifferant?......bob

 

[Bloo]

I was talking to an aircraft mechanic about that 2 days ago. His comment was that magnetic detection can find a smaller crack than dye can, but of course it only works on ferrous metals. Dye will work on either. I will be interested to see what responses you get to this. I have a steel part I would like to have checked.