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Old 25-10-2015, 09:56   #1
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Removing Paint From Aluminum Hull

I have a 45' alluminum boat. The hull is bare metal above the waterline all the way up to about 18" below the toerail. In other words, the top 18" of the hull is painted white. The paint has some blistering, so I'm considering removing all of the paint above the waterline so that the bare aluminum shows all the way up. Does anyone have any thoughts on how to properly remove paint from an aluminum hull?

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eric
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Old 25-10-2015, 12:23   #2
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Re: Removing Paint From Aluminum Hull

-Mechanical. Variable speed grinder with a "soft pad" type sanding pad. 36 grit sandpaper. This will remove the paint very fast. Unfortunately, it will also remove a bit of aluminum. Paint over welds will not be removable by sanding/or grinding as too much weld material will be sacrificed in the process. A very noticeable "swirl pattern" will be left behind.

-Abrasive blasting. Expensive. Messy. Does remove some metal if not careful. Good for removing paint from welds or other crevices that a sanding disks cannot reach. Leaves a dull grey "grain" type surface.

-Chemical. Expensive. Messy. Might take many applications of paint remover to be effective depending on type and thickness of paint. Does not remove metal.

I am not an expert at this. Others may have different or additional information.

Steve
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Old 25-10-2015, 13:24   #3
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Re: Removing Paint From Aluminum Hull

Just did a 10' test patch of paint remover today on our aluminum boat. The boat wasn't painted when originally built, but one of the POs painted it sometime along the way.... so we hope the hull is pretty fair.

We used Rust-oleum Aircraft paint remover followed by a Porter-Cable random orbital 80/100 grit. It required two coats of stripper followed by a lot of elbow grease to remove the paint, but came out great. Unfortunately, In my 10' patch I wasn't able to find a weld with a lot of filler, so don't know how that will go once I do find a section with issues.

I would guess that your hull is fair and the removal of paint will be pretty easy. Good luck.

Matt
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Old 25-10-2015, 13:27   #4
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Re: Removing Paint From Aluminum Hull

Thanks Matt. Mucho appreciated.
eric
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Old 25-10-2015, 13:54   #5
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Re: Removing Paint From Aluminum Hull

One issue I am seeing is that it looks like they aggressively sandblasted before applying the primer. I'm left with a slightly pitted surface once paint is removed. You may want to test under a small area to make sure you can match the bare hull finish. Our boats ugly enough that it doesn't matter
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Old 25-10-2015, 14:20   #6
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Re: Removing Paint From Aluminum Hull

Sand blasting way to abrasive Soda Blasting is the way to go
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Old 25-10-2015, 14:32   #7
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Re: Removing Paint From Aluminum Hull

eric-
I would suggest looking for a local soda-blasting guy. They're used to making on-site visits, and soda blasting will absolutely not harm the aluminum while it will take off the paint. If you can find dry-ice blasting, that's even cleaner (less residual material) but likely to cost more.
You do the tenting and tarping, the guy comes and hits it with the media, you ball up the ground tarp and you're all done. Fast and clean, with no risks from chemical exposure or changing the texturing on the hull.
In my book, fast and clean trumps a lot of other considerations.
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Old 25-10-2015, 14:37   #8
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Re: Removing Paint From Aluminum Hull

A grinder with a sanding disc is fine. The aluminium is much tougher than the paint so it is not difficult to remove all the paint with minimal effect on the aluminium.

Painted aluminium is normally left a little rough to allow the paint to adhere. So you may have to polish the previously painted areas to match with the rest of the unpainted hull.
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Old 26-10-2015, 10:01   #9
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Re: Removing Paint From Aluminum Hull

Having worked on Navy aircraft at sea for too many years, I have found that media blasting is the best way to clean paint and corrosion from Aluminum with out damage. I'm sure that the Company you find will know the best media to use, there are now many.
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Old 26-10-2015, 10:19   #10
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Re: Removing Paint From Aluminum Hull

Blasting but find someone experienced.
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Old 26-10-2015, 13:48   #11
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Re: Removing Paint From Aluminum Hull

I used a variety of methods on my hull, deck and topsides depending on the area and what I wanted to preserve from the original. Our topsides were coated by the manufacturer by Inversalu which is a Inorganic Zinc Silicate. Wherever possible I tried to maintain that layer so I had the topsides sand blasted in Venezuela to that layer. Was OK but very messy.

For the cockpit I used primarily a variety of paint strippers which were followed up with a aggressive (purple) Scotchbrite pad on a grinder. For the deck we used #80 sandpaper since we were going to Kiwigrip it and could use some texture.

Welds were and are the most difficult and for the most part I didn't worry about it too much. If every chip of paint was not removed, Mother Nature would eventually take care of it herself.
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Old 26-10-2015, 18:08   #12
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Re: Removing Paint From Aluminum Hull

I think soda blasting may be the way to go. I need to sort out where the bare aluminum is going to stop and the GLP deck is going to begin. What is that delineation line going to look like? I'd like to buff the entire hull to make it all look the same after the paint removal. I'm guessing I can find a soda blaster somewhere near Chesapeake.
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Old 26-10-2015, 18:30   #13
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Re: Removing Paint From Aluminum Hull

We considered soda blasting Hawk's bottom, because we had a lot of anti fouling build up. In the Chesapeake bay. The yard we were in organized a blasting company to come take a look and do a sample spot. They came, but really did not seem very interested in the job, and I don't hire people who are not interested in their work. So we got two guys with sanding disks to do it, which went perfectly - fast and good. We ended up just taking off anti fouling and leaving the existing barrier because it was in excellent shape.
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Old 26-10-2015, 19:45   #14
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Re: Removing Paint From Aluminum Hull

Probably a dumb question, but why does aluminum need a barrier coat? Unless this is the same meaning and function as a primer coat.

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Old 26-10-2015, 19:50   #15
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Re: Removing Paint From Aluminum Hull

Quote:
Originally Posted by hellosailor View Post
You do the tenting and tarping, the guy comes and hits it with the media, you ball up the ground tarp and you're all done. Fast and clean, with no risks from chemical exposure or changing the texturing on the hull.
In my book, fast and clean trumps a lot of other considerations.

We had our fiberglass hull soda blasted in the Chesapeake and the vendor did all the tenting, tarping and hauling away.

Everything else was as you describe (and he was very enthusiastic about his work).

Mark
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