I am starting my hundredth project this spring/winter. I am painting my 18' river skiff. I have rolled Rustoleum on before and does a fine job. Any other suggestions? Not looking for a high gloss, fancy job, just to cover and stay on.
wood, glass, aluminum...?
Aluminum. 18' North River sled. My bad.
aluminum finishing 101
Here's the official procedure for getting paint on aluminum. It sounds like you might want to be doing an inexpensive short-cut method, but I don't know of one. So here's the professional way to do it. Strip off all original paint. Paint removing chemicals are ok on larger surfaces. A wire brush (4" grinder with a wire brush wheel) will get small areas or paint that is easily flaking off. Don't worry about getting the aluminum "shiny" at this point, just get all the foreign material off.
Now you need to remove the oxide layer from the aluminum with a chemical etch. A product called Zep-A-Lume is common, but there are other brands. Get these items from your local metal and welding supplier. They are an acid mixture that must be diluted before use. Use chemical gloves, goggles, HEPA mask, and splash shield when using this stuff. Basically, you get the boat wet with your garden hose, then apply the acid using either a small pump-up garden sprayer (must be all plastic) or a sponge. Get the entire surface wet with the acid and let it stand for a few minutes, but do not let it dry on the surface. Don't do this in direct sunlight (it dries too quickly) and the surface temperature needs to be above 50°F for it to work (the warmer the better). Wash the acid off with lots of water. Oh yeah, make sure you do this in a place with excellent drainage. The diluted acids will break down in soil, but you don't want to have your runoff going directly into a storm sewer, garden area, or anyplace where pets can access the water.
Once that step is done, you'll have bright and shiny white aluminum. If the surface is too smooth, paint won't stick as well. So, I suggest lightly scuffing the entire surface with a wire brush or circular sander. It should be a light and even chaotic pattern so it doesn't show through the paint. Once that's done, you'll need to condition the surface, so leave the boat in your water friendly area for now.
Aluminum conditioning is done with a product called Alodine (other brands exist). You brush or sponge this yellow liquid (consistency of water) over the surface you're going to paint and let it sit for a few minutes. You then wash it off with water and it will leave the surface of the aluminum a nice golden color. After it's all washed off, you let it sit and thoroughly dry before you apply the paint. If there are any areas that you will not be painting, do not apply Alodine to them. Mask these areas off with plastic and good tape. Note you'll probably have to retape after washing off the Alodine and before spraying the paint.
I recommend a good quality automotive paint. Lasts much longer and looks a lot better than your industrial paints (Rustoleum, etc). If you don't care about color, stop at your local automotive paint store and see if they have any mis-mixed paints on the bargain rack. And you're going to need an air sprayer to apply the paint correctly. Start with a couple light primer coats. You may sand between coats just like you're painting a car, but don't get too carried away. It is a boat and you're going to run it into rocks and logs and stuff. Once you have an even primer finish apply the finish color in a couple light coats until you get good coverage. It will toughen it up to apply a good clear coat over everything to finish it off.
Now, that's the "official" method of getting paint to stick to aluminum. If you don't have an air sprayer or want to go through all the automotive finishing steps, at least prep the surface with acid etch, a scratch pattern, and Alodine before applying your paint of choice. If you simply "roll" on a cheap paint, it will still stick better and the finish will last a lot longer. Either way, good luck with your project.
Thanks Joat. Great info. Sounds like you've done this once or twice.
Yep, I've done my fair share (my Dad's a custom boat builder and I used to work at his shop).
Straight up painting of the exterior is easy. It's doing interiors with Zoltatone that's tricky. Every nook and cranny that you don't want painted needs to be masked off. Then you've got to do the normal acid-scratch-conditioning prep while getting all the water out of the boat in between steps. Then you've got to prime, base coat, spatter coat, and finally clear coat it all without getting any foot prints on the floor. It takes a special air sprayer to apply the spatter right and it also takes an artistic eye during the application to make it look good. Add to that the cost of the paint divided by the coverage and you get about $5 per square foot just in materials. It's cheaper to put down wood flooring in your house.
As Mike Rowe would say, "I can smell it now!" Fresh Zolatone is an odor that lodges itself in your olfactory senses forever.
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