Im building a new transom for my pontoon boat. All the aluminum is stuff I have scrounged up. Some of it is painted, and some is just dirty. I tried sanding the painted stuff and it isn't coming off very easily. I would like to take a wire wheel to it, but I believe that you aren't supposed to steel wire brushes on aluminum because it contaminates the metal. Some of the material is in sheets and I have no way of telling the alloy. I don't weld aluminum and my buddy who will be welding it can't be reached before I am done prepping this.

Can I use steel wire wheels to clean off paint?
Is there a way to tell if the sheet aluminum is an alloy that can be welded before putting a torch to it?

NO STEEL

Use a stainless wire brush, you can get stainless cup brushes for your angle grinder, as far as alloy someone with more experience will chime in, just put the wire brush DOWN :flipoff2:

i know every stainless fastner i have put in aluminum has corroded around the fastner,theres some kind of chemical reaction with stainless and aluminum.maybe the cup brushes are fine for cleaning,as long as it's not long time contact

3M makes a plastic bristle wheel, we have them on a buffer at school and use it to clean up aluminum all the time. They take off oxidation in a hurry, no idea on cost.

i know every stainless fastner i have put in aluminum has corroded around the fastner,theres some kind of chemical reaction with stainless and aluminum.maybe the cup brushes are fine for cleaning,as long as it's not long time contact

Stainless brushes and wheels are fine for cleaning aluminum. The corrosion you were seeing is common between dissimilar metals when in constant contact for a long period of time.

3M scotchbrite pads and an angle grinder. I prefer the roloc style attachment. They come in various grades of courseness, and diameters. 2-3" for small 90degree air grinders, 4" work fine on the 4-4.5" electric grinders.

Start with a course, then med, then fine.

I went out and spent 35 bucks on a cupped stainless wheel. It was very slow and chewed the hell out of the aluminum. I had some norton brand abrasive pad which I ended up using that worked like a charm. I still don't know how to tell if any of my sheet aluminum is weldable

If you smeared the material during cleaning you might have problems. Smearing traps shit under the material that's been mushed over.

Angle grinder works but you need to go light on the pressure & variable speed is a big plus.

I would chemically strip it, throughly wash it afterwards & then clean oxide off with a hand SS brush that is used on Al only.

I spent a few year welding aircraft parts in a factory. Best way to clear is acid etch, next is grind to smooth finish then a stainless brush non ferric type stainless like type 321. Last wipe clean(with clean cotton) with mpk or mek or alcohol, obviously you give that time to dry off.

If used in a boat it is likely 5052 series very weldable

I still don't know how to tell if any of my sheet aluminum is weldable

Like weedwacker said it's a 5xxx series alloy. The only non-weldable series are 2xxx & 7xxx.

Weld it up with 5053 filler.

In a small shop enviroment/home/etc/

you have a die grinder air>use flapper wheels>home depot,granger with spin on off adapter,mate.important
mate grinder max rpms with wheels<<<<<<<<<life/face shields!!!

The most prat>is for 4.5 elect grinder>again home depot,ace,etc
"flapper disk" or tiger paw"<both as above mate>>>>life /face fingers etc/mate>mate rps whit grinder & flapper disk!!!!!

Label with mag-markers,alum,so not to cross use with carbon steel etc.
Hope this helps>also use dust mask,clear face shields:d

This is what I ended up using, it really worked great.

Never seen those discs before, interesting. My transom needs overhauled next spring as well. The deflector/stiffener needs removed so it doesn't cause the short shaft outboard to cavitate as much. Therefore it'll need stiffness added elsewhere.........