True Grit

[tournyman]

To be able to Paint my motor cowling i need to sand it down and prime it first, what grit of sand paper would you use for a Force 120 HP outboard? Thanks

 

[1fullforce]

Re: True Grit

I Would Use A 320

 

[Frank Acampora]

Re: True Grit

First scrape off the decals with a single edge razor in a holder. Takes a little time but it is worth it. Then remove adhesive residue with Xylene. Purchase at paint dept of big lumber stores--your choice. Now you can sand without cobbling up the paper with adhesive. If you want to go all the way to the plastic use something a little coarser than 320 like 200 or even 120 on a power palm sander. If you just want to scuff so primer adheres well, then use 320. 320 is really too fine for paint removal. Before sanding the hood, glue all cracks with epoxy and rough sand to level them. The hood is plastic, not fiberglass, and resin will not adequately adhere. Fill gouges with bondo or marine grade filler and coarse level them. THEN sand. A good paint job is 95% preparation, preparation, preparation.

Spend the couple of pennies extra and use a good brand name primer and acrylic color coat. Do not use enamel.

Depending upon how well you want the finish to look, put on several coats (minimum of two--more is better.) of primer with light sanding in between with 320 and 400 grit. The finish coat will only look as good as the primer so take care and invest a little time here.

Spray on the first color coat. You will be surprised. The primer will look perfect, BUT--- Black or dark colors will show every imperfection like cellulite on a woman's a**, light colors not quite so bad but still show. Use spot filler to repair the imperfections then sand. Start with 400 grit and go up to 600 wet sanded with subsequent coats. Spray on as many coats as you have the time or patience to do. Spray light coats with additional on the corners and take care not to sand through on the corners. The more coats and sanding in between, the more lustrous and deep the final coat will look.

After it dries, glaze the final coat of color with a light spray of thinner only. This levels it and brings up the shine. Do not clear coat. With age, it tends to yellow and dull the color. Let it sit for about a month to be sure it is fully hardened before polishing.

Now that the hood is done, it is time to refinish the engine and leg. Right?

 

[RRitt]

Re: True Grit

with all due respect there is the perfect way as described by Frank and then there is the "good enough" way. No, the good enough way won't give you a perfectly smooth mirror finish but it will be 90% of the result with 20% of the work.

Go to harbor freight tools and buy a pack of sanding sponges for $3. Gently remove emblems. Use model paint and modeling paintbursh to touch up black on emblem. Scrape off decals taking care not to make any deep scratches. You can use WD40 and steel wool to get rid of residual adhesive. Avoid silicone spray lubricants as they can cause really bad fisheyes in finish paint. Wash the engine cover to remove dirt, grit, grease, and WD40. This is a really good time to contact cement a bunch of neoprene to the inside and reduce your noise level. It is also a great time to clean the sealing gasket and align the latches. If you leave the latching hardware on then make sure to cover it with masking tape (trim with exacto knife) right before laying down paint.

Get a bucket of water and put in a capful of liquid laundry soap. Start wet sanding with the sanding sponges. Sand away until you have a consistently smooth surface. Touch up any dings with 2part body filler or epoxy. Spot filler shrinks with time and a paint job that looks perfect the first day can start showing divots a month later.

now that you have a smooth substrate just shoot the color coat right on top of the old paint. That $10 gravity feed detail gun with purple handle from chinese tool depot does a great job for this type of project. Get an inline water filter and connect it to bottom of gun.

If your engine is white (early 80's) -
1 pint great falls transit district white mixed with 1 tablespoon light beige is very close to the chrysler color. add a few drops of beige to get exact match. let dry before evaluating color. paint changes color as it dries.

If your engine is blue (late 80's) -
Ford Deep Wedgewood Blue Metalfalke is the closest thing I have found to Force Blue. PPG # 5486

If your engine is black (Mercury era) -
just use the appropriate shade of mercury grey.

I like the PPG Acrlyic Enamel or Dupont Nason. Use hardener so that future exposure to solvents won't cause wrinkling. Follow directions. A "tack coat" is a very thin coat that dires quickly. A "full wet coat" does not mean dripping wet. It means uniformly applied and just barely thick enough to be shiny.

 

[ztim]

Re: True Grit

Hey Frank, wouldn't doing the leg be about the same process without the Bondo?
Bob

 

[Frank Acampora]

Re: True Grit

Pretty much unless it has dings in it. Then use marine grade filler because of its proximity to the water. Only real trouble spot is at the kingpin. very difficult to get in there and there is always a lot of grease in that area. You must take pains to clean it properly.

And then after all that work, if you waterski, the back shroud gets dinged up from the float and rope clip.

BTW: New decals can be purchased OR you can design your own and have a print shop that does car decals print them for you. Price is not that bad. I had two decals, mirror images, 16 X22 inches, made for 37 bucks each. That's probably only a little more than stock decals. Or, you can paint on your design. --Maybe get someone with a steady hand to do a little pinstriping---See where I'm going here? I need to get a life.

Hmmm! Wrong file! That's the next decal I'm going to have made. And no, It's not prurient, it's art. However, If the moderators feel it must go, I'll understand--we all have different opinions of what is objectionable.

 

[mark1961]

Re: True Grit

The paint on the exterior alloy parts of my 20 is starting to flake in places and i would like to give it a freshen up. If i was to take most of it back to bare metal would it be ok to use etch primer and then any good quality acrylic finish or does the primer and topcoat really need to be something special if i want it to last? Btw, i intend to put it to use in salt water most of the time.

 

[Frank Acampora]

Re: True Grit

On aluminum you can "get away with" regular primer if the engine is used solely in fresh water but Zinc Chromate primer is the only way to go if you want to ensure good adhesion and a lasting paint job. Salt water use pretty much demands it. Ain't cheap--costs around 8 bucks for a spray can in this area. But quality always costs more.

 

[RRitt]

Re: True Grit

Ideally you should prep the raw metal with alodine before applying any paints or primers. You can buy alodine 1201 from the aircraft spruce web site or pick up an "aluminum conversion coating" from any local autobody supply store. The conversion coating will probably be alodine put into a PPG or Dupont jug. There is a dried brand called chem-dip but you probably aren't interested in making 100 gallons at a time.

First, deep clean it with phosporic acid or metal-prep cleaner.
Second, brush or dip alodine 1201 (available from aircraft spruce).

IMO - best finish is
blast to bare with balontino glass-blast (ground glass)
etch with phosphoric acid
conversion coating with Alodine 1201
apply solid fiberglass or epoxy fills
seal with PPG DX1991
prime with Petit under-the-waterline zinc chromate
sand smooth
re-prime/re-sand if needed
shoot top coat of PPG or Dupont acrylic urethane autobody paint
let cure for 72hour absolute minimum before handling

 

[mark1961]

Re: True Grit

I have been having some trouble accessing this site to post a reply, not sure whats happening.

Thank you gentlemen for your responses, some very good information there. What exactly is the alodine treatment designed to do?