(And finishing other DIY Projects.)
Now you’ve invested all that time and effort into building an awesome trailer, how should you finish it? Of course we don’t want it to rust. And, we want it to last. So, here are some recommendations for trailer frame painting / finishing. Actually, we’ll cover the finishing of trailers in general.
While we could go a lot of different ways with this article, we’ll cover the basic steel frame (welding). Trailer frame painting is similar for other materials, including aluminum, though the prep is different. If you have another material, ask about prep from the source of the paint.
Prepare For The Finish
Paint shows a million flaws, so take your time and prepare the frame. While it may seem fine with a quick glance around, those ugly bits of weld will really stick out when it’s painted. Here are the areas to focus on:
Welds. The first step in prep is to clean-up all around the welds. Splatter is a big one, so knock all those little “BB’s” off and grind the ugly welds as needed. Most of the little “BB’s” will come off by hard scraping with a flat screwdriver or flat edged scrap of steel. A grinder works for the rest.
Welding usually leaves a residue that comes off pretty easily with a wire brush.
Oil and Mill Finish. New raw steel usually has a rust inhibitor coating on it. That’s the stuff that makes your hands black when you handle it. That all has to go. For the most part, you can wipe it off with a little soap and water. That will also get any other incidental grease and oil off.
Rust: With nearly all projects, there is a touch of rust that starts on a few pieces. No big deal, just make sure it’s completely gone before painting. Sandpaper, sand blasting, or whatever.
Surface Prep. The best paint jobs start with a really clean and slightly roughed up surface. We recommend sand blasting prior to trailer frame painting, but careful tedious work with sandpaper can do it too. I’ve done both, and they both take time to do them well.
Final Preparation. Hang the frame for painting if you can. Place it on a few points of contact if you can’t hang it. Finally, clean it super well with soap and water all over, then let it dry.
Options For Trailer Frame Painting
Painting is a pretty generic word for finishing. You can certainly “Paint” in the classic sense, but another option is Powder Coat. But which one should I use?
The goal in finishing the frame is to protect the metal. Paint covers and seals the metal, and so does powder coat, but they do it differently. Paint is a liquid that comes on, then dries in place. Powder coating is a dust of plastic that electrostatically covers the metal and “bake” in an oven where it melts and adheres to the surface.
These processes are not the same. Also, as we compare, it’s not just a comparison of Paint vs. Powder Coat. Powder Coat can be made more durable and weather protective with a zinc primer, and various types of paint are not the same. For instance, a rattle-can will not provide the toughness and longevity of a 2-part epoxy primer.
I’ve heard it said that paint can’t last as long as powder coat, but I’m not convinced. For me, powder coating instead of trailer frame painting has become a matter of convenience as much as a matter of durability. I think Powder Coating gives you both. However, about 25 years ago I found the 2-part epoxy primers, and that changed the game. Properly applied, the epoxy primer is amazing for durability. Then, you can paint whatever color you want over it.
This Video shows a good example of typical DIY trailer frame painting. I think they did a great job — both with the primer and the paint.
Recommendation – Skip The Rattle-Can
Yes, I know many people do it. Rustoleum or other brand spray paint is easy and makes a nice look — for a short time. Even the ones with primer inside don’t really give a quality, durable finish. You certainly can, but you’ll also be looking to do a “refresh” again in a couple years. While I can’t speak for you, IMHO I don’t like going back to refinish past projects. I’d rather do it right the first time. The two options below are much better, again, in my opinion.
Recommendation – Powder Coating
I powder coat my trailer frames now and include the special zinc primer for extra weather protection. I personally think that is the best overall option — partly because I have it done professionally. The end result is a robust and beautiful trailer frame.
Down Sides: It’s not something you can do yourself. You must take your frame to the powder coat facility where they have the equipment to coat it and a huge oven to bake it. Secondly, it can be pretty expensive. Third, many colors are available, but if you’re picky, paint has more options.
For me, I find it most convenient to take the frame in, have them do the final preparation, and complete the job. So, if you can afford it, this is my top recommendation.
Recommendation – Trailer Frame Painting
Another option I recommend is to painting with a 2-part epoxy based primer. It has a base primer, then an “Activator” or “Hardener”. When mixed together, they create a chemical reaction that hardens it to make it really tough.
I was first introduced to it about 25 years ago. I sanded the frame by hand, cleaned it thoroughly, the painted it. It is still going. That trailer spent a lot of time on the Bonneville Salt Flats — which is the worst environment I’ve ever experienced.
The first year at Bonneville everything rusted right through the paint. Then I found this two-part epoxy primer, and I redid everything on the trailer and the vehicle frame. We raced several more years out there with no more rust — unless we scratched through somewhere. That said, we scratched the paint many times but rarely scratched through the epoxy primer.
Painting is definitely more of a DIY process. You can do it in a make-shift paint booth in your garage, and get a good result if you take your time. In this case, the 2-part epoxy primers take a little more because the cure time is limited. That said, you can just as well have the painting done professionally if you want.
Down Sides: It’s messy, and it takes some time to setup a good make-shift paint booth to do it DIY. You have to mix small batches and spray till you run out, then mix more because the cure time is pretty short.
Paint over the primer in any color you want.
More Info On Epoxy Primers:
It’s the 2-part epoxy primers I recommend, and they need to be for “Bare Metal Applications”. You must get both the primer and the hardener, then mix them together in just the right proportions. Make small batches because it will solidify in your painter after some time.
I just did some research on various epoxy primer brands. I found one option — Cromax 2580CR — that costs $363 for a gallon of primer plus $294 for the hardener. Wow. That price seems pretty outrageous to me.
The can in the photo has obviously been on the shelf for a long time because it is covered in dust. At that price, it will probably stay there till earth ends.
For more information, visit the Cromax website.
Another option is this one from Medallion, at $26.10 per quart of primer plus $10.50 for the hardener. Note that this is a quart price. Gallons are also available. I don’t know the difference in quality compared to Cromax, but they claim the same things. The store owner says it’s a great product — if that means anything.
For more info, follow this link to the Medallion website.
My past success with the 2-part epoxy primer was with the PPG DP-40 product. That stuff was awesome, but I don’t think they make it anymore. I hear the newer DPLF line is a little harder to work with, but I don’t have personal experience. Some of it might be sanding it for top coat perfection — like on a car body. That’s kind of what I’m reading in the forums — but most trailer frame painting doesn’t have to be that perfect.
Sorry, no photo of the PPG products. However, the PPG website has the list of products. While there is a lot of info there, I find their website hard to use. Hard to find what you’re looking for.
While looking around, I found this little spray can of epoxy primer from Spray Max. See the images below. It’s like a rattle can, but you have to activate it from the bottom. Activation mixes the 2 parts inside, then shake well and spray. While I don’t know the quality, it looks really convenient for smaller projects. No sprayer clean-up.
This can was marked at $25.60 so not too bad if it’s as good as the store owner says. While it would take a lot of cans to properly prime a trailer frame, it looks great for smaller projects.
For more information, visit the Spray Max website.
One Last Tip:
On the note of disposable paint sprayers, when I use epoxy primers, I use a disposable aerosol sprayer. It’s basically an aerosol top that screws onto a glass bottle with paint in it. You put in the paint (or primer) you want, and it effectively becomes a spray can.
While the one in the image is pretty good, there are others too. I’m told that local places like Walmart and Harbor Freight have things similar. However, I have not verified it because I don’t shop those places very much.
To me, this is a great way to make any paint a spray paint. Or, in this case, any primer a spray primer. (Check to see if you need to thin your choice of primer before spraying it. I think these aerosol sprayers do better with thicker paints than normal pneumatic sprayers. Just check before jumping into trailer frame painting.
For this one, check out the Preval website.
Good Luck With Your Trailer Frame Painting!
(Or Crane, or Shop Press, or Table, or Cabinet, or whatever you’re working on.) We hope the tips above are helpful. Feel free to leave a comment if we’ve missed something.