Re: painting an outboard lower unit..
I painted my lower unit and after two full seasons it's still looking very good - no chipping or peeling.<br /><br />The procedure is the same as any paint job: sand/rough up, prime (special aluminum primer), paint - and maybe sand between coats if desired and needed. You can also clear coat afterwards.<br /><br />I went to a specialty paint shop (specializes in car painting) and they were very knowledgable about prepping and painting aluminum - it's worth the couple extra bucks their products might cost compared to Home Depot - the advice and guidance is worth it imho. They recommended various 3M buff pads for the sanding and roughening. It was easy to use and it allowed me to evenly rough up the irregular surfaces. For larger flatish surfaces, I'd use various grades of sand paper just like any fine finish job. I basically followed the following advice I found on this forum and elsewhere on the web (search: painting an outboard and such) and the results were great. I plan to do my entire kicker, new decals and everything, this spring.<br /><br />Here's the info I've found (various sources separated by .......):<br /><br />Pertaining to the areas to be painted, clean off any oil, grease, etc with acetone. Use a fingered carbon scraper (or a tool of your choosing) to chip off any heavy rust and corrosion that might exist. Sand the areas with #60 (if needed), then #220, then #320 sandpaper to obtain a smooth surface. <br /><br />With compressed air blow off the sanded surfaces, then wipe down all of the areas with acetone to make sure the surfaces are perfectly clean. <br /><br />If the surfaces are cold, or even cool for that matter, warm the surfaces with a hand help propane torch that has a blow torch type tip. Do not get the surfaces hot enough that they will fry the paint.... you just want them warm. <br /><br />Have the location well lighted so that you can see that the paint is flowing on smoothly (not a dry fluffy look) but not to a point where it is running. This will take a little practice. <br /><br />You'll find a sighted viewing angle whereas you can see that the paint (although wet) will appear shiny.... this is the desired effect. <br /><br />Spray in whatever reasonable bursts are required. Do not use a constant never ending spray of length wise, width wise, coupled with circular wise action just to get the paint on the area unless you intend to enter the engine in a circus display. <br /><br />Prime the surfaces with what is called "Zinc Chromate Primer". It is developed specifically for aluminum that will be used in salt water. This is available in spray cans in most marine dealerships, and possibly elsewhere. Perhaps there has been another primer developed in recent years specifically for this aluminum/salt water use that I'm not aware of..... check into that possibility. Zinc chromate primer is green there is another type of green primer intended for aluminum just make sure the primer is intended for aluminum as well as the paint youll be using for the top coat.<br /><br />Take a look at the paint made for the specific engine you have. In the big picture, it wont be much more expensive than other spray lacquers or enamels. The other paints will also work just fine, but might not be the exact color you want.<br /><br />After the paint has been applied, you can again use the propane warming method if needed which will give you a certain baked on glossy appearance. <br /><br />Before attempting to do the complete job, I'd suggest that you experiment on a smaller scale until you're fairly sure of what the outcome will be. <br /> <br />
..<br /><br />Hardest part is the prep: Removing dirt, wax, grease, and loose paint in all those hard to get places. Best way I've found is to use a wax and grease remover first, then depending on how bad the existing finish is sand it thoroughly using as fine grade sand paper as possible. Old decals can and should be removed with a razor blade type scraper, then use a solvent to remove the glue, then sanding as required. If you have to use 120 grit to get the rough stuff off, then finsh it with 220 or 320. Wipe it clean again with wax and grease remover to get any dust remaining from the sanding. Mask up any areas that you don't want oversprayed. I prefer spraying starting with the primer recomended for whatever topcoat you plan to use. Some light sanding may need to be done between coats per instructions from paint mfg. <br />Really not that difficult to get "that show room look" on a limited budget.<br /><br />
<br /><br />It is definitely manageable with a budget but the prepping is crucial. I'd recommend final sanding before paint with 600 paper, that should help eliminate the need for sanding and buffing out the final finish. When you read the instructions, follow them closely, temperature is IMPORTANT! Allowing the paint to "flash" (turn a semidull eggshell look between coats) is also important. Find an old piece of metal or something to do a "test spray" before hitting the motor, some paints go on thin and some thick, for the sake of 30 seconds you should be able to gauge speed and distance of your passes with the can unless you have air and a spray gun. Anything can be painted:metals, plastics, fiberglass, etc... Some materials just need differant attention in the prepping.
