SX-M repainting tips needed

[Wanna Tango]

Hi everyone. Have a 2000 VP SX-M that I removed and had sandblasted to remove all the various (many) coats of different paints and bottom coat paints.
Been researching and reading other similar posts on this forum and get more and more confused as to what to use for base coat/primer. There are thoughts that you should use zinc phosphate primer and others that you should use other stuff.
I went to the Volvo Penta shop I have nearby and he was telling me just go with the VP Blue Grey Primer P/N 1141562 since I am bare metal and the paint with VP Spray Enamel P/N 3851219.
Am I overthinking this or is this right approach? I don’t want to do ALL this work just to put the boat in the water and 3 mi the later all the paint is gone.
Any tips will definitely help this diy’er. Thanks!

 

[Donald0039]

Hi everyone. Have a 2000 VP SX-M that I removed and had sandblasted to remove all the various (many) coats of different paints and bottom coat paints.
Been researching and reading other similar posts on this forum and get more and more confused as to what to use for base coat/primer. There are thoughts that you should use zinc phosphate primer and others that you should use other stuff.
I went to the Volvo Penta shop I have nearby and he was telling me just go with the VP Blue Grey Primer P/N 1141562 since I am bare metal and the paint with VP Spray Enamel P/N 3851219.
Am I overthinking this or is this right approach? I don’t want to do ALL this work just to put the boat in the water and 3 mi the later all the paint is gone.
Any tips will definitely help this diy’er. Thanks!

Go to Boatered.com. Look under Engines, etc and there is a pinned thread on repainting outdrives. It's the prep that's important. Forget self etching primer.
It's an excellent writeup.

 

[Scott Danforth]

I use Moeller zinc dichromate primer (rattle can)

Followed by an epoxy primer (touchup gun) and then base coat and a final coat of clear

I do not moore my boat, those that do can comment on layers of bottom paint.

 

[kd4pbs]

There are two ways to paint aluminum; the right way and the wrong way.
Scott outlined the right way. Some people even use Alodine as the first coat on Aluminum. I've done both in the past, but I never kept the boats long enough to be able to give any input on whether or not the Alodine made things hold up longer. Logic and other people's experience in finishing aluminum seem to indicate it is batter than the zinc chromate itself.
Zinc chromate primer has been harder to obtain lately, so this time around I decided to go with the easily obtained zinc phosphate. If I keep this boat long enough, I'll have more experience as to whether or not it's as good as the chromate version.
You'll likely find lots more accurate info about the subject from aircraft restoration forums than from boat forums just because those who deal with aircraft refinishing usually have more knowledge and experience with finishing aluminum than Jim Bob with a rattle can.
Just slapping on some kind of unknown primer as your base coat sounds like a great way to get more practice stripping and painting aluminum in the near future.

 

[Donald0039]

There are two ways to paint aluminum; the right way and the wrong way.
Scott outlined the right way. Some people even use Alodine as the first coat on Aluminum. I've done both in the past, but I never kept the boats long enough to be able to give any input on whether or not the Alodine made things hold up longer. Logic and other people's experience in finishing aluminum seem to indicate it is batter than the zinc chromate itself.
Zinc chromate primer has been harder to obtain lately, so this time around I decided to go with the easily obtained zinc phosphate. If I keep this boat long enough, I'll have more experience as to whether or not it's as good as the chromate version.
You'll likely find lots more accurate info about the subject from aircraft restoration forums than from boat forums just because those who deal with aircraft refinishing usually have more knowledge and experience with finishing aluminum than Jim Bob with a rattle can.
Just slapping on some kind of unknown primer as your base coat sounds like a great way to get more practice stripping and painting aluminum in the near future.

A self etching primer may well etch the aluminum but whatever is removed from the aluminum will dry as part of the primer. Do you really want that?

 

[kd4pbs]

I am not sure I understand… the primer does not leave a residue or remove aluminum. It chemically etches through whatever oxide layer there may be and attaches to the aluminum chemically as well. Any conversion which is done from the reaction is indeed what we want, because paint won’t stick to aluminum oxide very well at all. The zinc acts as a less noble metal element which effectively neutralizes any galvanic reaction from happening if small amounts of moisture reaches the base metal. On top of this base primer,, an epoxy primer effectively seals the base layer and gives the base color coat or one step finish coat an excellent coating in which to adhere that is compatible with enamel, lacquer, or urethane.
This is a well known industry standard process for painting aluminum. The OEM would have done the same thing, which is why it is best to leave as much original paint as possible if a pristine finish appearance is not a requirement on a boat.