Posted: 9/19/2009 11:40:35
I am ready to prime my Air Cam vertical stab. I have marked each part with an indelible pen.
I am wondering if alodine will remove the markings from the aluminum? If not I am also wondering if the primer will cover them up?
Would using tags be a better idea? I'm in big trouble if I can't identify each piece after priming!
thanks in advance
Posted: 9/19/2009 18:05:50
Probably depends on your prep process/type of primer. Alodining by itself won't remove the sharpie, but if you use alumiprep or someother solvent before alodining expect the marks to go away. I've used zinc oxide primer over sharpie and it usually bleeds through so you can read it. I don't have experience with other primers. My suggestion would be to mark a scrap piece and put it through your prep and primer process, then there will be no question.
EAA Ch 494, Corona, Ca.
Posted: 9/19/2009 18:59:52
I use sharpies in a lab. Isopropanol, ethyl acetate, acetone, and ethanol remove the ink from glass. Try rubbing alcohol (this is 80% isopropanol) or acetone. None of these will touch the metal.
Posted: 9/19/2009 22:19:58
You don't want to place indelible ink . It will prevent the chromic conversion. Purchase manila tags that have a wire attached from McMaster-Carr. I use a coat hanger to hold the part and tag while etching, alodining and priming. The tag stays on until I'm ready to rivet.
I give a corrosion prevention workshop at Sun n Fun every year and the above is my suggestion to fellow builders.
Posted: 9/20/2009 15:40:55
Thanks all for the input.
I think the bottom line is that the acetone prep will remove the sharpie marks, so I will likely use the manilla tags.
However, an electric engraver also seems like a great idea... but is it appropriate for alclad?
I am concerned that tags, if used, may get alodine dipped, or painted over (I am using a metal finishing shop to do the painting, so I won't be able to control this part of the process).
Posted: 9/27/2009 16:29:23
I have seen sharpie marks that have been completely removed from aluminum surfaces with laquer thinner magically bleed through when primed. The process is much like dye penetrant testing. The sharpie ink actually penetrates the metal.
Metal tags stamped with a number would be the best idea.
Posted: 9/27/2009 22:18:10
I ended up deciding that metal tags were the best way too.
Rather than stamping I've been using a $12 Harbor Freight electric engraver to hand engrave the tags, which works great!
Also, I have learned that acetone will easily remove sharpie (and most any other) marks.
That step is done so next is etching, alodine and priming.