new guy question=- alumiprep

[LENKEARNEY]

I am just thinking about this and was wondering why so many steps in finish preparation?

seems like there are several steps to prepping, priming and coating aluminum parts, why is that?

Len

[Kyle Boatright]

Wow, you just stepped into a BIG issue.

There are a multitude of processes out there. Some simple, some easy. Some more effective than others. Some (many?) builders take the position that if a single step corrosion protection program is good, one with 50 steps must be better.

Seriously, I think you'll find that most repeat offenders did their most difficult and time consuming corrosion protection job on their first airplane and went with simpler solutions later. For instance, I did the entire etch, alodine, prime thing on all of the internals on my RV-6. Next time, I'm probably using rattle can zinc chromate on the faying surfaces and leaving the rest of the inside in natural aluminum. Cessnas last 50 years or more without primer, so a partially corrosion protected airplane should last even longer...

You can check the RV-list archives and find a huge amount of information on corrosion protection and priming. The thing is, you need to decide how much corrosion protection you really need for your climate and storage situation, and pick a system that meets that need. *Extra* corrosion protection is wasted time, money, and useful load.

[13brv3]

Really, that was a great reply. I've worked my way down to NAPA 7220 rattle cans, and if it weren't for resale, I'd skip it all together. Since the current project is a QB, I'll feel compelled to at least rattle can any part that I do.