Leveling aluminum

[Arkman]

I have some scratches in my hull, they are really only cosmetic but I am getting ready to paint and I'm wondering if there is something I can do to "level" these out so they don't show through the new paint or if just painting it will sort of fill this in and level them out? I'm thinking something similar to when you fill in drywall scratches with drywall mud. Obviously I dont want to use drywall mud but something similar.

Thanks!

 

[sschefer]

Re: Leveling aluminum

I have some scratches in my hull, they are really only cosmetic but I am getting ready to paint and I'm wondering if there is something I can do to "level" these out so they don't show through the new paint or if just painting it will sort of fill this in and level them out? I'm thinking something similar to when you fill in drywall scratches with drywall mud. Obviously I dont want to use drywall mud but something similar.

Thanks!

You can use body putty. It's a creamy putty that most automotive paint stores carry. It will harden in 24 hours and then you just sand it smooth. If they aren't that bad just put a couple of coats of primer on it. I sand my aluminum with 120 and then prime and sand with 220 and never see any scratches.

 

[tashasdaddy]

Re: Leveling aluminum

body putty does not like water. i say spot coat with primer and sand.

 

[sschefer]

Re: Leveling aluminum

body putty does not like water. i say spot coat with primer and sand.

It's o.k. if you prime after. That's how it's intended to be used.

 

[Arkman]

Re: Leveling aluminum

I think that the marks are small enough that just the spot prime and sand might be the ticket. Any suggestions on what puddy to use if I need it. I'm assuming I need something special for an aluminum boat.

 

[sschefer]

Re: Leveling aluminum

I think that the marks are small enough that just the spot prime and sand might be the ticket. Any suggestions on what puddy to use if I need it. I'm assuming I need something special for an aluminum boat.

Ask the person at the store, there are several brand names available. I've used a 3M product but don't remember the number off the top of my head.

 

[erikgreen]

Re: Leveling aluminum

I'd recommend trying the primer too, assuming it's an aluminum primer.

Bond-o or similar body putty meant for cars will not last on a boat below the waterline, even primed. It absorbs water, that's all... it's ok if it's not submerged. You can get similar putties and epoxies like Marine-tex for boats.

Whatever you use, test the aluminum for adhesion first... not much will stick to aluminum oxide, which is what it's coated with.

If it were me, I'd sand down any ridges and fill with primer, or if the scratches were too big I'd clean down to shiny metal, acetone, then use some of that low temp aluminum filler rod (like alumi-weld or similar) to fill them before sanding, priming, and painting.

Erik

 

[5150abf]

Re: Leveling aluminum

I had good luck with JB Weld, it sands nice and doesn't show through the paint and it sticks, I wouldn't use bondo, just give it a good scuff first.

And definitely use etching primer on any bare metal, if you don't your paint will start to bubble after a short time, Auto Zone, $4 a can.

 

[fishrdan]

Re: Leveling aluminum

I had good luck with JB Weld, it sands nice and doesn't show through the paint and it sticks, I wouldn't use bondo, just give it a good scuff first.

And definitely use etching primer on any bare metal, if you don't your paint will start to bubble after a short time, Auto Zone, $4 a can.

That's what I did on several areas of my aluminum hull and outdrive. I also trimmed the JBweld with a razor when it was stiff, but not completely hardened. After the JBWeld was completely hardened I block sanded it level. In a few tight areas I was using a 1.5" x 1.5" block, but it kept the filler level.

 

[J. Mark]

Re: Leveling aluminum

maybe

http://www.midwayautosupply.com/showproduct.aspx?productid=14245&affiliateid=10050

there are other liquid steels as well

such as

http://www.alvinproducts.com/Products/Products.asp?id=2

which looked very promising to me for your use.

Filling small scratches with primer is fine, but any gouges or dents would need something that builds faster

 

[sschefer]

Re: Leveling aluminum

Bond-o or similar body putty meant for cars will not last on a boat below the waterline, even primed. It absorbs water, that's all... it's ok if it's not submerged. You can get similar putties and epoxies like Marine-tex for boats.Erik

Yes, 3-M does make above and below the waterline fillers for aluminum and glass. I buy mine at West Marine.

As for filler material adhesion, sand the aluminum with 80 grit, form and level it with 80 grit and final sand with 220.

To make sure the paint sticks, etch prime any bare aluminum with the correct etching primer for the paint you are using. Make sure that the etching primer is applied as soon as possible after sanding the aluminum to a bright white. Prime with the correct primer for the paint you are using as soon as the etching primer is dry. If more than 24 hours have passed since applying the etching primer, sand it off and start over.