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Finishing Bare Aluminum

Posted: Thursday, January 11, 2018 8:01 PM Quote
Hi Folks,

I'm new to Stewart Systems and could use some guidance regarding aluminum prep.  What I've got is a set of Citabria wings that are being converted to aluminum spars.  The ribs are untreated and in very good condition.  The new spar parts are bare, polished (not shiny but nicely finished) aluminum.

It was recommended to me that the spars be primed (DuPont VariPrime was suggested) before assembly and any holes or scratches be dressed before covering.  I've decided to use Stewart Systems for the covering but haven't considered SS metal finishing products.  

Can someone please go through the options step by step?  The goal of the project is to have a safe and soundly flying airplane, not a museum piece so I'd prefer to not strip and seal every last aluminum part like factories might do for corrosion proofing.

Thanks in advance for the help!  I guess I'll shop for a couple of garage heaters while I figure this out.  :)

Posted: Thursday, January 11, 2018 8:18 PM Quote
Posted: Thursday, January 11, 2018 8:48 PM Quote
OK, so I remembered reading something in the user manual and found this

Aluminum Surfaces – Clean all surfaces with STEWART
SYSTEMS EkoClean Heavy Duty Cleaner (E670),
followed by STEWART SYSTEMS EkoEtch
(E675). The EkoEtch may be applied while the
aluminum is still wet from rinsing the STEWART SYSTEMS EkoClean
Heavy Duty Cleaner. Use a red Scotch Brite pad and remove the glaze from
the aluminum. Let the EkoEtch work for 3-5 minutes; do not let EkoEtch
dry on the aluminum surface, rinse with clean water. Remove excess water
with compressed air. Prime with STEWART SYSTEMS one part
Primer/Sealer (E75XX) or EkoPoxy (E76XX) when aluminum is completely
dry, or within 12 hours of using the EkoEtch.

What are the benefits/limitations of stopping after the one part Primer/Sealer?  Is the EkoPoxy more of a finished coat for parts that will be visible after the plane is done?

Would a household water supply with some mineral content (not very hard water but not soft either) qualify as "clean water" for the rinse?  

Is there a minimum temperature for the wash and etch steps where I'd likely have to be outside as opposed to in my heated shop?

Thanks!  I'm (slowly) making progress here.