I run an aluminum boat for a living. I use plain old Jasco paint remover and it does not harm the aluminum at all. Paint remover will not remove anodizing since anodized aluminum is a very hard aluminum itself. What you never want to put on aluminum is sodium hydroxide or what is commonly known as drain cleaner. Sodium Hydroxide (NaOH) dissolves aluminum.
What you do use to prepare aluminum for painting is Alumniprep 33 for removing oxidation in hard to get at places and Alodine 1201 which is a chemical converter and helps the primer paint adhere to the aluminum.
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Originally Posted by Spirit28 
Don't know about applying heat to remove corroded in fastners though - you would have to be really careful not to affect the temper of the alloy. Is the way to do it?
I need to remove an unused exit box and the PO did not an anti-corrosive compound (eg duralac) and the machine screws will not budge - I'm afraid I'll shear the head off if I apply too much pressure. |
Try putting a few drops of Alumniprep 33 in the area where the stainless screws into the aluminum. Apply the alumniprep, tap the fastener, let it sit, tap it some more, rinse with fresh water, blow it out with an air hose...repeat the process for a few days or until it comes out. The Alumniprep dissolves aluminum oxide.
As far as heating goes, aluminum has a much greater expansion rate than stainless, so you don't have to heat aluminum up all that much to make a difference. You wont change the temper of the aluminum as long as you keep the heat down and stay well below its melting point. In my experience, sometimes these two tricks work and sometimes they don't.
Why some people screw stainless into aluminum without applying something to displace the oxygen is beyond me.
When screwing the stainless back in, use Tef-Gel to prevent oxidation from seizing the screw in place again. In my opinion Tef-Gel is the best stuff for this application because it remains gooey and never hardens...therefore displacing any water or oxygen that would otherwise get in there. As aluminum expands an contracts, the Tef-Gel stays there, unlike some bedding compounds which can delaminate or shrink, eventually allowing water to get in.