Painting a boat motor.

Discussion in 'Boat Modification Journal' started by RiverKing, Aug 3, 2009.

  1. RiverKing

    RiverKing Active Member

    Messages:
    2,232
    State:
    Yellow Spr
    Anyone ever done this? What type of paint do you use?
     
  2. DANZIG

    DANZIG New Member

    Messages:
    6,672
    State:
    West Virginia
    Shamelessly Stolen from another board,,,,

    "As told to me by a pro:

    1.Shoot a very thin coat of the zinc chromate primer.

    2.While zinc is still wet, shoot a thin coat of sandable primer. The two will combine and allow the topcoat to adhere. If you wait for the zinc to dry, primer and topcoat will not adhere correctly.

    3.Allow for the combo to get tacky. Don't touch with palm side of your finger to test. Use the backside of you finger so as not to leave mark or oils. Surface should be tacky, but no transfer of color to your finger.

    4.Shoot your topcoat in at least two thin layers, preferably three. Topcoats should be allowed to dry between applications.

    5.All sanding and cleaning should be done before any paint is applied. There should be no need to sand between applications."
     

  3. RiverKing

    RiverKing Active Member

    Messages:
    2,232
    State:
    Yellow Spr
    Any special paint though?
     
  4. Grimpuppy

    Grimpuppy New Member

    Messages:
    3,556
    State:
    Concordia, KS
    I would guess they are doing this because they are not using the correct paint over the zinc. Zinc primer is great, but there are only certain paints that will cure when applied over the top let alone adhere to the zinc.

    You must use an epoxy, acrylic enamel, or a polyurethane paint over a zinc rich primer for proper cure and adhesion.

    Best way is a zinc primer, an epoxy intermediate coat and a polyurethane top coat.
     
  5. moriver

    moriver New Member

    Messages:
    416
    State:
    Missouri
    Go by the auto part store and get a Scotch Brite pad. Scuff the surface up and shoot it with enamel. Let it eat.......
     
  6. DANZIG

    DANZIG New Member

    Messages:
    6,672
    State:
    West Virginia
    "You must use an epoxy, acrylic enamel, or a polyurethane paint over a zinc rich primer for proper cure and adhesion."

    I'll admit that I have only a small amount of experience with the zinc primer, but I have yet to notice a problem with paints other than those.

    Why not?? Peels, or what?
     
  7. Grimpuppy

    Grimpuppy New Member

    Messages:
    3,556
    State:
    Concordia, KS
    You can apply more over the older zinc chromate.

    I was referring to the newer zinc rich moisture cured organic primers, since zinc chromate is almost taboo anymore for industrial use except for some specialized applications. After now remembering that an outboard is aluminum, you can't use a zinc rich organic primer on it anyway. If you were painting steel it would be the way to go.

    Since it is aluminum, I would skip the zinc altogether and use a self etching epoxy primer with a polyurethane top coat.
     
  8. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    Depends on why you want it painted. Motors on fishing boats are supposed to look scuffy, scarred, veterans of many encounters with the wild. If your gonna be tubing or skiing to impress girls, you probably need a new boat and motor anyhow. If your hunting, simply have a camoflague bag made up you can slip over the motor which will also break up its outline.
     
  9. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    Seems industries are moving away from the zinc chromate in favor of the Molybdate for occupational health reasons.
    The MSDS is the same though:confused2:

    Personally I like the characteristics of zinc chromate alot better.
    Open a can of molybdate and close it right back up and it will skim over.
    Next time you go back to use it (even the next day) you've got a can contaminated with the gooey skim. Damn near impossible to spray out of it unless you strain the crap out of it. Just more mess to contend with and more contaminated materials to contend with.

    My main concern with zinc chromate and molybdate on the private consumer level is disposal. It is some nasty stuff that even rags or dried brushes don't need to wind up in household trash.

    As far as I know outboard manufacturers have a part number for paint.
    It comes in a spray bomb. I would go that route following the directions for prep on the can. KISS simple.
     
  10. 7mmmag1

    7mmmag1 New Member

    Messages:
    94
    State:
    Oklahoma
    Ain't nothing wrong with red scotch brite and a can o Krylon for us fellas with empty bank accounts (just dont use red paint, unless you want a pink motor next year)
     
  11. Streaker

    Streaker New Member

    Messages:
    2
    State:
    Ga
    I am far from expert but have done alot of DIY painting. I used engine degreaser on mine to make sure it was grease free then I washed it again with dawn dishwashing soap. sanded it down with 320 to get rid of all the loose stuff and washed it again. The next day I sprayed it with Zincrom spraycan primer from Napa P/N 7222. Just a thin coat. You don't want to cover like paint. After that dried I scuffed it very lightly with a gray scotchbrite pad then washed it again. Then Sprayed with a light coat of Rustoleum paint. Let that tack up then another good coat. I put about 4 good coats of rustoleum on and then let it cure for a week at least putting it in the sun every chance I could to let it cure. I didn't use clear on the motor itself but I did clearcoat the engine cowl after adding stickers. Thats my process but I have to be honest and say that I am working on my boat at the moment and haven't had a chance to get it in the water so as far as it holding up I can't say. I think it will work very well for a poor mans paint job. If it doesn't I won't be ashamed to admit it on the board so I'll report back if it does.