Painting Aluminum Hull

I've got a painting prep question. Can I sand the existing paint and leave it for a couple days? I got my game plan. Sand, then Zinc Chromate the bare spots and scratches, then prime the entire hull, then sand the primer, then finish coats lightly sanding between each. But I can't do this all in one day. Can I sand the boat and wash it with 50/50 then leave it for a couple days before I apply Zinc Chromate? After the Zinc and the next regular primer, can I sand it and leave it for a couple days again before final? Does leaving a sanded boat for a few days hurt anything?

Re: Painting Aluminum Hull

No, it doesn't hurt anything other than time for dirt or any other impurities to collect on the surface. Wipe it down with reducer and then dry it with a clean rag before the next coat. Be sure to use a tack rag before you start putting on your final coat.

Re: Painting Aluminum Hull

you could, plus skip the zinc chromate, if you coat with an - aluminium filled mcu coating/primer -- called Aluthane. If you want the aluminum look just leave the aluthane exposed, otherwise topcoat with an enamel within a week or so.

Re: Painting Aluminum Hull

Actually it depends on the type paint and primers you are going to use. Some primers say you have 72 hours to paint or you have to resand. And some base coat paints state that you have 24 hours to clear coat or you have to sand again...

Re: Painting Aluminum Hull

Yep, in order to properly answer this we need to know what specific Paint products you are using.

Re: Painting Aluminum Hull

Ok thanks guys. Makes sense. I guess I need to make a decision on what primer and what finish paint so I know what the manufacturer recommends regarding sanding times. I'm leaning towards Rustoleum (available at Lowes or Home Depot)or Majic Paint (available at Tractor Supply). Trying to stay away from high priced "West Marine" stores. Any thoughts on those two paint manufacturers? The aluminum boat will spend most time covered on a trailer. And when I use it, it will only be freshwater lakes. So I don't need any special bottom paint for salt water. Other than several dozen dock scratches and tie down rub marks from PO, the original paint is sound and actually shiny on most of the boat (other than all the scratches and the keel from sliding on sand). Real good paint job for 27 years old. There are a few corrosion spots on the transom that I'll repair with a layer of JB Weld Marine. I assume the old wooden transom was PT because where the aluminum on the back of the boat was screwed tight against the wooden transom, there is some pitting (looks like a chemical reaction). Any recommendations on paint for my type of application (freshwater) would be appreciated.

Re: Painting Aluminum Hull

Some people here have had good luck with a combination of the Rustoleum enamel (box stores) you're refering to, and Majic Hardener (tractor supply). Any areas that have exposed aluminum should be cleaned with an aluminum prep and spot treated with an etching primer or alodyne product. You can use a primer over the painted hull for a sealed, unified base

If you're spraying, thin about 25%

If you're rolling/brushing, thin about 5-10%

If you use the hardener, protect your lungs!

Re: Painting Aluminum Hull

I just used the Rustoleum Professional Enamel with Majic hardener and reducer. As far as adhesion goes, this paint isn't going anywhere. It's already cured rock-hard and I've dropped some metal tools on it with no chips.

My process was to pressure wash all the aftermarket paint off, sand with 320 with a palm sander, and an acetone wipe down. Then I hit all the bare metal spots with self etching primer, and put Rustoleum bare metal primer on the entire surface and sanded again (if you're spraying you can skip this second sanding, I believe). Then I painted using WOG's ratio for rolling (I ended up brushing, but that's another story). My paint job is a 6 or 7 out of 10, but you can probably do better than that on the finish coat. Anyway, my point is that this seems to be a good recipe for adhesion, and the hardener adds gloss as well. Listen to the previous poster's warning about lung protection if you use it.

Re: Painting Aluminum Hull

Looks like a GREAT job. I hope mine comes out as well. We'll see in a week or two. Still working on transom and pitting on rear. Next is paint prep. Thanks for the tips and warnings.

Re: Painting Aluminum Hull

"Ok thanks guys. Makes sense. I guess I need to make a decision on what primer and what finish paint so I know what the manufacturer recommends regarding sanding times. I'm leaning towards Rustoleum (available at Lowes or Home Depot)or Majic Paint (available at Tractor Supply)."

I used a self etching primer from one of the local parts stores (army green color) and was not happy at all with the adhesion, so I sanded it off and started over. My next SE primer was the rustoleum from Lowes ($8.00 a can, but worth it) stuck like glue! I also like that it was white because I was spaying on a light colored top coat. Check out the link in my signature to my 52 Duracraft restore, there is a picture of one of the actual cans of primer I used. My top coat is PPG Omni with omni MH167 hardner and MR187 reducer mixed 4:1:1 spayed on three coats waiting 30min to an hour between coats. Of course I did all the same prep work to the bare aluminum that many of the others have mentioned above. I did use the Majic Tractor and Implement paint for the bottom of the boat and am really pleased at how nice it laid out and how durable it seems to be. I would have used it on top, but they did not have the color I wanted at my local tractor supply store LOL (imagine that, not too many peacock colored tractors running around) I'm used to painting with PPG and dealing with my local distributor for PPG that's why I had them mix some up for me. Good Luck, I'm sure it will turn out great!