Re: Painting aluminum
I know there are several threads out there about this but they don't answer all my questions. I will be painting my boat soon, it's stripped down to bare metal and I will scuff with red scotchbrite. Is it absolutely neccessary to use alodine? What are the downsides if I don't. What's the difference between zinc chromate and self etching primer? I know the zc is some pretty nasty stuff. I will be using Rustoleum for primer and paint I just want to make sure I have a good base for it to adhere to as I don't want to do this again. Any other advice would be great also.
Hello BN ..
Here is the low down on Alum and prep for paint..please read this posted from a member here..
http://forums.iboats.com/showthread.php?t=457159
The Alumiprep (
http://www.aircraftspruce.com/catalog/cspages/alumiprep.php ) is a cleaner for alum and explained in the above thread..
You can sand dry or wet .. I like Dry sanding for prep before Alumiprep..
So you have your Alum nice and Clean/Converted to accept a primer ?? um..not so Fast there ..
At this point all you have is a nice Fresh Alum Surface to do the next step ( you prepped your alum to accept compatibility for the next coating ) .. at this point you dont have some kind of Magical "coating" on your alum .. its just CLEAN as Clean can get ..
So now lets say you take my advice and buy the AP33 and wash down your boat .. now you think its time for some kind of "self etching primer" ... hmm..
Alodine (
http://www.aircraftspruce.com/catalog/cspages/alodine1201.php ).
At this point you have Raw Clean Alum .. and now you want to prime..but is your Primer coat compatible with Clean Freshly sanded Alum ?? or .. Did you Alodine it ..
The Alodine is basically a a thin "tie" coating that bonds to your alum and accepts certain Primers .. ( not all primers ).
Zinc chromate is the standard primer for salt water applications ( masts etc. ). ZC is not always applied ..
Primers are Always applied to Alum applications .. some are ZC .. while others are epoxy based ( 545 etc. ).
Raw alum should take special care on the process and timetables of the job .. Its a Bang Bang thing ..
YD.