Summary: Here’s how you can professionally paint your aluminum duck boat. Included are answers to frequently asked questions, step-by-processes for painting both bare aluminum and over existing paint, camouflaging your boat, and additional painting tips.
1. Do I need a sprayer, or will a brush work?
This depends upon how you want the finished paint job to look. I have sprayed and brushed paint on different duck boats I have repainted or built. If you want a very smooth finish spraying is the way to go. Brushing paint does take much longer than spraying but does give the paint a slight texture. Just as with paint, primer can also be applied with a brush. Even when using flat paint a smooth finish will reflect much more light than a textured finish, especially when wet. Also, a Wagner power painter will will just fine as a sprayer.
2. What type of paint should I use?
Many good paints exist today and both solvent-based or acrylic based paints can be used to paint your duck boat. I have good luck with Parker Coatings duck boat paint which is a solvent-based paint and available in several camo colors. Their paint is also available in spray cans. Krylon also manufactures duck boat paint, which is water based and available in several colors. There are also many other quality marine paints available, but you may have problems finding it in camo colors.
3. Do I need to sand off the old paint?
If you want the new paint to be perfectly smooth such as the paint on your truck the answer is probably yes. But sanding off original or factory adherent paint on a duck boat is not only a waste of time in my opinion, but will also cost you more money especially when repainting aluminum.
4) Do I need a special primer to paint aluminum?
A regular primer sticks to the material it is applied to by mechanical adhesion. Mechanical adhesion is accomplished by primer settling into scratches created from sanding, and then grabbing onto these scratches it shrinks when drying.
An etch primer is formulated to be put on bare metal such as bare aluminum. This type of primer not only provides a mechanical adhesion, but also a chemical adhesion. The chemical adhesion is achieved by an acid contained in the primer, which etches itself into the material it is applied to. The mechanical adhesion is achieved as describe above in regular primer.
1) Masking tape, ¾" being most common
2) Masking paper – newspaper will also work
2) Sanding block or power sander
3) 600, 800, 100, 1500, 2000 grit sandpaper
4) Scotchbrite pad
5) Grease Remover - Dawn dishwashing soap and rubbing (isopropyl) alcohol
6) Paper towels
This is the route I would recommend for most situations. Keep in mind I only recommend this method if the current finish is factory original and not peeling or flaking. Because we already have a surface the paint can adhere to versus bare metal, no special primer is needed.
The first step is to thoroughly clean the existing paint with a grease remover as suggested per above. Once dry then remove any gloss with 600 grit sandpaper or a Scotchbrite pad. Even if the existing paint was flat, the existing surface should be scuffed up to promote paint adhesion. The finish should look dull, hazy, or milky.
Now either brush off or wipe with tack cloth all surfaces to be painted. Next wipe these same surfaces with a rag soaked in rubbing alcohol. After the alcohol has dried you are ready apply 2-3 coats of the color you have chosen, letting the paint tack between coats and then let completely dry. If 2-3 coats are not enough to give sufficient hiding of the "old color", continue with more coats.
I would recommend waiting at least 2-3 weeks for the paint to harden before using the boat, otherwise the paint will easily scratch or mar.
First step is to sand of the old paint down to bare metal using desired grit sand paper. 80 grit works best for this, it's coarse enough to remove the current finish and only leaves scratches behind that are easily removed. Once all the old paint has been removed lightly sand the surface/s again with 180 grit sandpaper to remove the larger scratches left from the 90 grit. If you want a really smooth finish sand surface/s again with 400 grit sandpaper. Now either use a brush or tack cloth to clean up all surfaces to be painted.
The next step is what makes painting aluminum unique. A conversion coating needs to be applied to the bare aluminum. This is most easily accomplished with a self etching primer. This type of primer is most easily applied from a spray can or is available for use in a regular paint sprayer. Another method is an acid based etching liquid that is sprayed on and then rinsed off with regular water. In either case you local automotive parts store should have both types available and will also be able to assist you in this process. Be sure to follow all manufacturers’ safety precautions when working with these products.
If using the self etching primer above, once it’s completely dry your ready to apply 2-3 coats of the color you have chosen, letting the paint tack between coats and then let completely dry. If using the etching liquid you’re ready to spray down a couple coats of regular primer, letting the primer tack between coats. Once the primer is completely dry to apply 2-3 coats of the color you have chosen, letting the paint tack between coats and then let completely dry.
Once again I would recommend waiting at least 2-3 weeks for the paint to harden before using the boat, otherwise the paint will easily scratch or mar.
Once your paint has been allowed to dry at least a couple of days you can start apply a camo pattern. I would recommend choosing a camo stencil. Next choose a couple of different flat camo paint colors and apply the darker colors first. This results in camo pattern that has “shadows”. Several good camo paints in spray cans are available today and are available from Parker Coatings and Krylon. An alternative to camo stencils is to simply grab a handful on long grass or a shrub branch against your boat and then apply the spray paint. You may want to experiment on a big piece of cardboard first.
Always use a sanding block. You will be much more efficient when using a sanding a block and also will not put deep scratches into the aluminum. You can purchase a sanding block or make one out of about whatever you desire.
Surface preparation is a must to proper paint adhesion. Keep away from silicone products or grease/oil while doing the project. If you have naturally sweaty/greasy hands, it may be a good idea to wear rubber gloves or wash your hands periodically while working.
Prepping is the most important step in any painting project! If your not going to take your time don’t expect any primer/paint combination to make up for your laziness.
Important: It is critical for your own safety to carefully read and follow all manufacturers instructions and warnings!