Stripping paint/corrosion from aluminum?

CCrew · #1 September 14th, 2003, 02:57 PM

I'm looking for any suggestions on the best way for stripping corrosion and old paint from a bunch of aluminum stern drive pieces.

Inclination is to take it all apart, glassbead, prep and paint, but that's going to be a chore. Any "quality" shortcuts from the pro's would be appreciated!

Roger

tmac58star · #2 September 15th, 2003, 12:53 PM

I use a $5 strip the paint off drill/grinder wheel I got at Walmart. Not wire. Some kind of composite material. Cleans things up well, costs very little and doesn't scratch the finish. On the same aisle as the drills.

Paul Moir · #3 September 15th, 2003, 01:47 PM

I'm with the timster. I used chemical strippers before switching to these - they're much better. 3M hard black ones (looks kinda like a sponge) are really fast, but they will chew the aluminum a bit. Mind you that's good for fixing corroded areas. 3M brown flexible ones are slower, but nicer on the aluminum and you can get into corners with them. If your doing a lot, get both.

Wear a dust mask. Inhaling zinc chromate is not recommended.

CCrew · #4 September 15th, 2003, 06:25 PM

Thanks guys for the responses. I'm looking at getting into some nooks and crannies that even a dremel would be hard pressed to maneuver in... Seems that these stripper wheels would be a tad large?

Specifically it's all the gimbal/transom hardware.. not like a large area.

Thanks again,

Roger

SBPD1717 · #5 September 17th, 2003, 09:21 AM

Using a chemical stripper would be the easiest but what if the sterndrive wasn't disassembled?

Would the chemical stripper eat the gaskets? I am looking to repaint my sterndrive because of corrosion but don't want to disassemble it to paint it?

DJ · #6 September 17th, 2003, 08:27 PM

CCrew,

If the old p[aint is on there that good, don't remove it. Just make sure it's clean.

Wash the bare AL spots with a 50/50 solution of vinegar and water. You can wash the whole thing, it won't hurt the painted areas.

Then, apply zinc chromate primer to the bare spots.

Finish with a the top coat of your choice.

CCrew · #7 September 18th, 2003, 12:50 AM

djohns19,

Thanks for the response.

I guess it may or may not help to make myself a tad clearer. :-)

I don't have an issue with the remaining paint, as much as I have an issue with the areas that were bare aluminum and are now pitted, and encrusted with a scaly oxidation. So far, it's even resisted efforts with a wire brush to remove. While I had indeed intended to prime with a zinc oxide etching primer, I'm somewhat averse to painting that over the existing oxidation. Common sense (or maybe lack thereof?) tells me that I need to remove that oxidation prior to the priming.

As the third owner the boat was presented as never having been in salt water, to which I can only shake my head seeing what I'm seeing now!

Is that the purpose of the vinegar, in that it's acidic and will neutralize the oxidation, or is the vinegar simply used to etch the surface so that the primer will bond better?

Were it steel, I'd just have it hot-tanked, but being aluminum, there wouldn't be anything left if I did!

ratherbefishin · #8 October 24th, 2003, 06:52 AM

While the most common method is mechanical stripping[ wire brush, sanding, sand blasting] chemical stripping is very effective, and much less labour intensive- plus you get it all-tough to do with sanding.

Go to www.napierenvironmental.com and take a look at the new generation paint strippers-non toxic,no fumes and won't burn your hands on contact.They are used in the aircraft industry.

DJ · #9 October 24th, 2003, 08:56 AM

CCrew,

Nothing beats sanding. I've done several aluminum boats. Check out this thread.

http://www.iboats.com/cgi-bin/ubb/ul...;f=26;t=000917

Plus, for sealing seams use Gluv It. Available at: www.westmarine.com

It's simple to work with and does a fantastic job.

This was the last one I did.

http://mypeoplepc.com/members/djohns19/djohns19/

ratherbefishin · #10 October 26th, 2003, 04:40 AM

I agree sanding has been the traditional way to remove paint, but it has drawbacks- not the least of which is it is labour intensive, plus the fact that no matter how careful you are, seams, crevices, around fittings, rivets, it is almost impossable to clean the old paint right off.That's exactly why a chemical stripper not only is much less time consuming, it gets those hard to reach spots- exactly where paint failure begins when the old coating has not been properly stripped.

If you go with one of the new generation paint strippers, they won't damage gaskets, or other fittings,or harm the substrate be it aluminum orgel coat, plus are totally benign- they don't burn skin, have noxious fumes or are environmentally harmful.Spray or brush it on, wait overnight, and powerwash it off.You are now down to the base substrate, ready to prime and paint.