Well Aluprep is an acid degreasant make it shiny type of thing and so far if you wear gloves and rinse everything well it doesn't seem to be too harmful. The next phase, Alodine is a rather nasty and poisonous liquid. In small quantities it is ok but the amount you need to treat all the ali parts is just out of the question. Not only is it poisonous it is very difficult to get rid of. I am trying to find out how and where I can bin the stuff safely. So long as you dont breath it in, eat it, get it on your skin or soft tissues, it is ok to use. The big advantage is the corrosion protection it gives for little or no weight gain. Paint is the other alternative but you will of course add weight. I am going to see what the cost of the local alodine bath will be and then I will try the following:
totally enclosed inaccessible areas (fin, rudder, flaps, elevator etc I will alodine
Inaccessible but inspectable clean and paint with primer only
External surfaces primer and paint