Painting Aluminum Pod Help Please

[Cannonball]

Here’s what I have done:
Sanded down my boat pod to bare aluminum where corrosion took over. (Only about 10% of the project went down to bare aluminum) Left the rest powder coated and scuffed the surface. Used Alumaprep(a chemical acid wash). Used Alodine. Washed off. Used interlux epoxy Primekote thinned with interlux 2633. Scuffed surface. Prepped surface with interlux 2633 thinner. Applied 1 coat of interlux Brightside thinned with about 5% interlux 333 thinner. Rolled on and tipped with a brush after. It looked great.
And this is where it went sideways was the next step. I scuffed the surface and cleaned up with interlux 333 thinner. Applied a coat of interlux brightside and most of it looked like the first picture below. (I didn’t thin it this time as I figured it may dry a bit faster without thinner)

Might I add I have 2 heaters and 1 dehumidifier outside in a small enclosed tarp shelter keeping it a decent temperature and out of the elements from when I started this never ending project.

So I sanded that mess down. Vacuumed the dust. This time wiped it down with a damp rag then a tack cloth. Then applied a coat of interlux brightside thinned about 5%. And the finish looked like the second picture. Another mess. Just a bit of a different looking mess. Does anyone have any ideas what I may be doing wrong. Looking for someone who has a lot of experience for answers.
My dad seems to think the aluminum is cold causing the paint to react.
It’s starting to get expensive and time consuming.
Looking for someone who has a lot of experience for answers. Thanks for any input and tight lines.

 

[mikep]

Looks like your solvent it softening the coating below it. You really should be stripping the entire pod down to bare metal and bringing back from there. Solvent based coating over powder coat are kinda a no go.

 

[Brando]

Agree with above strip to bare metal and start fresh. I have had good success with interprotect on bare aluminum but there are other options start fresh, it’s a pita and feels like a waste but as you continue to overcoat different products your results will likely stay the same. Is this being done with the motor and pod still attached to the boat? Does the coating harden or remain soft?

 

[ship happens]

Spray paint does that if you let the paint dry too long before recoating. I think you need to put your second coat on sooner. Also make sure you formulate the coats the same.

That prime coat should make a paintable surface for you no problem.

If your trying to re paint it to showroom bling, and a super durable finish, sand last and re powder, or sand blast and endura paint job. Only 2 ways.

 

[profisher]

On my powder coated aluminum pod I removed it from the boat, sandblasted it to bare and had it re-powder coated.

 

[Brando]

On my powder coated aluminum pod I removed it from the boat, sandblasted it to bare and had it re-powder coated.

I would go epoxy over powder coating though from what I have read it’s more durable and my own experience leads me to the same conclusion anything I have had powder coated always begins to flake off after a few seasons..

 

[SpringVelocity]

If it flakes off in first few years it usually has not been done right. A lot of shops don't prep the metal unfortunately. See this a lot. If it is done right it has to be sandblasted, dipped, zinc primer underneath, and then powder coating.

 

[SpringVelocity]

On my powder coated aluminum pod I removed it from the boat, sandblasted it to bare and had it re-powder coated.

That would be my recommendation. It has to be sandblasted and redone.

 

[Buckethead905]

I would call interlux technical support and give them all the details, they are pretty well versed with what is compatible with their products.

 

[YachtMech]

Must be stripped to bare metal, the solvents in the paint can react with the powdercoat. painting over powdercoat is a waste of time for multiple reasons and you have just discovered a couple of them.


interlux epoxy Primekote is for wood or fiberglass, this is not the correct product to prime aluminum, it even goes as far as denoting it is not safe for aluminum outdrives. you could have pre coated it with 2000e as a primer then used primecoat afterwards but then you are basically double priming.

also the brightside is specifically for above the waterline. so wrong paint as well if your boat is in the water alot, fine if its just dropped in every now and then. if the boat is staying in the water then idealy you split up the paint job between above and below waterline.

if you go to their website it walks you through the process of what you should be doing and what products to use for bare aluminum extending underwater.

this is the guide for what you need to do

https://www.interlux.com/en/us/paint-guide/BW073-how-to-fully-repaint-bare-aluminium-zinc-galvanised-steel

As harsh as it is, you basically just wasted all your time and a bunch of money on the products you have been using. The powdercoating needs to be removed completely as it will also likely continue to peel off from corrosion, not to mention the solvents have likely distressed it to the point that it will fail to continue to adhere correctly.

also the problem you are having it in their FAQ guide

Solve Flaking, Cracking, and Crazing in Boat Paint | Interlux

www.interlux.com

I think totalboat makes an aluminum specific above/below waterline paint that is probably the type of product you are looking for, seahawk as well, and there are some others as well but cant remember them offhand.

 

[Brando]

Dustless Sandblasting of Canada

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www.sportfishingbc.com

 

[terrin]

On my powder coated aluminum pod I removed it from the boat, sandblasted it to bare and had it re-powder coated.

How long did the first powder coat last and how long has the second one lasted and is it still holding out from peeling?

 

[Gear'n'beer!]

If it flakes off in first few years it usually has not been done right. A lot of shops don't prep the metal unfortunately. See this a lot. If it is done right it has to be sandblasted, dipped, zinc primer underneath, and then powder coating.

Dipped in what?

 

[SpringVelocity]

Dipped in what?

Placed in dip tank special solution. Takes off any contamination in metal, and I think it etches it slightly for better bond. Not sure mixture. The shop I uses exclusively does this, and it is a process. A lot of the issue with other shops is they skip this step. I notice a difference. Especially with aluminum with saltwater etc.

I don't use epoxy a lot, but if it was awesome I think the railing companies would use it more. Maybe it's just the cost.

 

[Gear'n'beer!]

Interesting, never heard of this. We have a couple powder booths and products just get blasted, blown off, primed and powdered. I know versatile does some sort of power wash etch before powder.

 

[SpringVelocity]

Interesting, never heard of this. We have a couple powder booths and products just get blasted, blown off, primed and powdered. I know versatile does some sort of power wash etch before powder.

Yeah it makes a difference. The prep is most important I think.... Also as you know some powders aren't that great. Some are far batter.

Wish I had more experience with epoxy just have no demand for it...

 

[profisher]

Terrin, My boat is 30 years old next year and the pod has been powder coated twice. The present job was done 4 years ago. The original application was still fairly good but it had flaked off where the motor bolts to the pod as there was no padding there to keep it from breaking through/cracking the coating and allowing water penetration. I used a thin dense piece of rubber this time between the motor and the pod to help prevent that from happening. Victoria Powder Coating does dip the bare aluminum to etch it prior to applying powder...they also off gas bare aluminum by heating it up to 400 d for half an hour before hand as well. You can Google the proper process for applying to aluminium...I did to educate myself so I could make sure my pod was being done properly.

 

[profisher]

Preheating the Part: This method is the most popular to eliminate the problem of outgassing. The part to be coated is preheated above the cure temperature for at least the same amount of time to cure the powder to allow the entrapped gas to be released prior to applying the powder coating. This solution may not eliminate all the outgassing if the part has an enormous amount of entrapped gasses, where the gas just keeps being released, no matter how much or how often you preheat the part.
This is done to prevent small pin holes in the finished product which would allow moisture under the layer and cause delamination down the road.

 

[ship happens]

If your just looking for a durable coating and not worried about a factory shine finish.. you can use a product from PPG call amerlock2. This is a super heavy duty epoxy paint. Can be applied to bare aluminum or any type of metal surface. Can be recoated ontop itself. Can be use on materials that live under water. We use this stuff on industrial applications in the commercial marine world. Limited on colors.


Powder coating is a pain in the butt. Sandblast and do not get a finger print on the part and it works great. However the part that's not easy is where you have a bolt, or where and engine sits against it. The pod builder I use for the fancy powder coated pods drills his engine mount bolt holes a size bigger and installs nylon sleeves. Along with a uarathane tape that will not let the engine rub through the powder coat. As soon as powder coat chips through, the salt will work it's way in and there is no way to stop it. Really finicky but when done right makes a nice finished product