saltwater and alluminum corrosion

[answer3]

update: the pressure washer cleanup worked pretty good. all the salt buildups are gone!

However, I noticed that the paint around several rivets was lifted making some kind of bubbles. I wire brushed some of these zones and the paint came off easily. Is it a sign of galvanic corrosion caused by salt buildups on the rivets? (don't have a picture of that here, will take one tonight and post it)

Also, the parts with bare aluminum that were behind the center seat I removed still show signs of corrosion even after pressure washer cleanup. I tried to wire brush the zone, sand it with 220 grit sandpaper, even polish with a buffing wheel in some spots to give it a try. This removed the white particles on the aluminum but there are still some darker spots below that stay in the aluminum no matter how hard I try to remove them. I guess the corrosion went deep... You can see that on the picture below:


From what I read here in the site and your comments, I have to stop the corrosion with chemical treatment then apply primer/paint then wax. Hopefully it is not too late! What would be a good chemical treatment to remove corrosion? Phosphoric acid, white vinegar, bar keeper's friend? Also, should I use something like Rust Encapsulator or POR 15 to help contain corrosion / prevent it from spreading?

 

[answer3]

Here are the bubbles around the painted riverts

 

[answer3]

And found this slimy stuff coming from under the ribs in many places under the boat, after I power washed it. Any idea what that is?

 

[answer3]

nobody?

 

[Fishfreek]

After treating with something like OSPHO you can't go wrong with PORT 15

 

[answer3]

thanks! after power wash, I cleaned with bar keeper's friend then powerwashed and degreased with simple green. next step will be OSPHO then paint. I will post pictures when it is done

 

[answer3]

looks like por15 is to use only on bare metal, not on previously painted surfaces. Because the paint inside the boat is in good shape for 90% of the whole surface, I don't want to strip it and add por15 on top of it, it would be way too long. plus the price of this stuff is crazy... doing the hole inside of the boat with it is going to kill my budget :shock:

I already started treatment with ospho, looks pretty effective. I am going to spray OSPHO to make a small layer on the bare aluminum parts that have corrosion so it makes the impermeable coat that protects from further corrosion. But then what primer do I add that would stick to both ospho and the previous paint? Would Rustoleum latex aluminum primer work in this case? it seems good for adding over previous paints but not sure if it will stick to ospho since they say it is best to use oil based paint over it. epoxy 1k primer also seems pretty good to add on previous paint, but again, not sure if it will stick to the ospho... I am lost... please help me guys!!

 

[CedarRiverScooter]

I would call or email OSPHO company & get their recommendation on the best paint to use.

 

[uncndl1]

This Primer tutorial from member Johnny should help you sort out some questions:
https://www.tinboats.net/primer-and-paint-basics/

 

[answer3]

This Primer tutorial from member Johnny should help you sort out some questions:
https://www.tinboats.net/primer-and-paint-basics/

This is one of the things I was looking at and made me think about latex aluminum primer or epoxy 1k, but the OSPHO is messing up all this plan since the manufacturer says it is best with oil based primer instead of latex or epoxy primers... I don't want to have the paint lift up or detach after a few months because of the OSPHO coat I put underneath.

 

[uncndl1]

Tractor Supply carries an oil based primer for $20/gallon,
Rustoleum must also.
Also could check with paint company you're looking at

Sent from my SCH-I545 using Tapatalk

 

[answer3]

Thanks. I found the oil based primer #7780 from rustoleum that would be compatible with OSPHO, but it says in the instructions that "smooth, hard, or glossy finishes should be scarified by sanding to create a surface profile" which I think is the case for the inside paint in my boat. Is this the case with any primer whatsoever or are there different primers that stick without needing to sand the old paint?

 

[CedarRiverScooter]

I worked with a paint engineer who said that there is almost never an adhesion issue when old substrate is sanded. Sometimes you can get away without sanding, but who knows when those conditions are just right?

 

[answer3]

thanks for the reply, let's do some sanding