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prepping aluminum

Posted: Monday, March 18, 2013 9:58 PM Quote
First, what is the easiest way to get the old glue off parts so they can be prepped for recovering? After the glue is removed from aluminum what is going to give the best corrosion protection? I have a good supply of alodine but some have suggested epoxy primer on top of the alodine. I'm not opposed to that but I try to minimize adding weight with more coatins than required. Will the glue adhere properly to alodine? Regards, Dana LaBounty   Sumter S.C.
Posted: Wednesday, March 20, 2013 4:16 PM Quote
What kind of old glue? Poly-tac? To remove solvent based glue brush a heavy wet coat of MEK over the glue and lay an old T-shirt over the area brushing more MEK through the T-shirt. Let soak for about 1-2 min and remove the T-shirt which will lift off the old glue. EkoBond must be mechanically removed but it does not need to be removed unless you have big lumpy chunks on the surface. If EkoBond is on the surface just brush a new light wet coat on and let dry be fore applying the fabric to the structure.

Are you building a seaplane or ag-plane and need the corrosion protection? If not then just glue the fabric on and go. All steel parts should be primed and painted. IF you want to prime aluminum then either primer will work. The difference between standard EkoPrime and the 2 part EkoPoxy primer is that epoxy primer is solvent resistant. On structures like wing ribs it's not necessary to use the more expensive epoxy primer. Our glue will not dissolve, lift, or cause any defect when applied over any primer or paint. Either way prime over clean bare dry aluminum that has been etched and scuffed with Scotch-brite and properly/thoroughly rinsed clean.  Always remove any oils or grease before etching or they will interfere with the etches ability to properly clean the aluminum and can lead to poor adhesion of the primer.

No need to use alodine unless you are working with old aluminum that was corroded and you hand to remove the corrosion with etch and scotch-brite. If you have clean new looking aluminum just etch-pressure wash-prime. The key to having primer stick to aluminum is to not leave any residue on the surface of the aluminum.

Posted: Wednesday, March 20, 2013 9:02 PM Quote
   Thanks for responding. The glue I'm removing is whatever Great Lakes used in 1978 with cotton. I'm already doing the MEK and wrapping rags. The only bit extra is I use a big sheet of plastic to work on and fold over the top of what I'm working on to slow evaporation. I was just hoping someone could suggest something less toxic than MEK.
   I have much bare aluminum like ribs and such. To be sure I have this right, as long as I clean etch and prime I should be good to go? No need to use alodine? If there is no need for extra steps and more expensive process I'm all in favor. I'm already spending enough time and money. Thanks in advance, Dana LaBounty
Posted: Thursday, March 21, 2013 11:59 AM Quote
You can make it easy and just sand smooth the old glue residue, no need to take it all off. If you are sand blasting steel I usually burn all the old glue and paint residue off with a torch before sandblasting.

I normally only use alodine if I had to remove corrosion from the alum otherwise I just clean, etch, clean again, and prime it.