How to Paint Aluminum

I did some 5 minute googling and it seems like painting aluminum takes days to paint because you need to pre-treat the aluminum first. Is there a quick and dirty way to paint aluminum if we are willing to sacrifice quality? I’m imagining something where you put 1 coat on overnight and that’s it. As long as it looks good enough from 10 feet away, its good enough for us. If that’s impractical, how long does it take?

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Get some spray paint, a sander (powered is ideal, elbow grease will work too) with sandpaper, and some chemical cleaner like acetone or isopropyl alcohol. Sand the aluminum, wipe down with the chemical cleaner on rags, spray and let dry. Coat again if you have time.

It doesn’t take more than a day or so. If you were anodizing or powdercoating, then it’d take a lot more time.

The sanding is just to roughen up the surface enough for the paint to stick to the aluminum; the cleaner takes off all the crud left over from the sanding.

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Apex Robotics 5803 has been painting our brackets and gussets since 2016. Last year we finally got a finish we were really happy with.

Custom gussets are typically orbital sanded first to remove burs, but COTS gussets are painted with no prior treatment.

We used Krylon Pro Enamel Safety Red (K05923000) which is a high flow, fast drying gloss red spray paint. We do 2-3 light coats on all sides using wire hangers to hold them, and allowing about 15-30 minutes between coats. Once we’re happy with the coverage, we hang them in front of some heat lamps (2x 250 watt, purchased from Home Depot) and let them heat-dry for about 10 hours, usually overnight. Here’s some photos of our setup and results: https://photos.app.goo.gl/zQ1GeAqyy3qdAruu9

They hold up pretty well over the season. I recall Art Dutra had a nice post circa 2011 with much more detail on process and best practices, if I find it I’ll link it at the bottom. You can get a bit nicer finish with better surface prep like Eric mentioned above, but this method has worked fine for us. The heat lamps don’t really “bake” the parts as much as help keep them warm when the garage they’re hanging in gets very cold overnight and would otherwise cause drying issues.

Here’s a photo of the front end of the arm at District Champs (4th event of the season). You can see the corners have chipped or worn off, but overall they still look bright red.

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You can also try contacting 846 for information on how they paint. IIRC most of their robot is spray painted each year, and they do a pretty good job of it.

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Echoing Eric, we hit everything with an orbital sander, wipe down with solvent (usually) and put on a few light coats of Rustoleum paint+primer. Nearly everything is painted just as we’re closing shop wherever we can lay down newspaper or hang parts up with zipties.

Some people have asked if powdercoat, so I guess it works okay.

2815 rattle-canned the last couple robots I did with them, and I’m not even sure we did the solvent step. Our main priorities:

  1. Disassemble the robot and cover up any bearings or things that shouldn’t get paint.

  2. Remove ALL the burrs. (The first year we rattle-canned, it was one of those #allblackeverything years. Any filing work would wreck the finish, and obviously painting in the pits is a no-no.)

  3. Prime, according to the can’s directions.

  4. Paint, according to the can’s directions. Couple light coats.

  5. Reassemble.

We were fortunate to have some legit artists on the team that knew how to follow the directions, and the robots came out looking great.


5402 also painted the robot I did with them, simple rattle-cans but I believe we did use some solvent on that one. (I wasn’t in charge of painting.) That finish came out nice; you can see the state of things after one event here.

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What we did last year was use a wire wheel to scuff up the aluminum. Then we took a wet rag to get off the aluminum dust. After, we would spray paint the aluminum and let it dry. There would be a minimum of 3 coats then, we sprayed a clear coat to make it sealed off and protected. (MAKE SURE YOU’RE IN A VENTILATED AREA!)

We have rattle canned the robot for years, and for the past couple, parts get painted before we assemble the robot, or they dont get painted (time crunch doesnt allow for paint at other times, plus works into our manufacturing and assembly process).

  1. Debur / grind down clearance issue welds.

  2. Lacquer Thinner (I believe that’s the solvent we use) to remove grease, sharpie marks such as part numbers and indicators when welding.

  3. Glass-blast parts that fit in our mentor’s cabinet (same step as before welding typically)

  4. Paint with light coat (Krylon Brand Specifically)

  5. Revist and touch up where needed

  6. Dry overnight or throughout meeting.

Our paint setup basically consisted of some tarps on the ground, a pole spread between two ladders to hang parts from, some work lights, and a large heater. We are looking to setting something nicer up this year since nearly every part gets painted. Once it ls done welding and cleaned up, it immediately gets painted before anything gets assembled.
At our first event, it seems like people ask us often if we powder coated and are shocked to hear it’s just rattle-canned.

If you have some scrap material laying around the shop, it might be wise to practice with that, so you can get your process figured out.

Like the instructions on the can say, surface prep is important. And spraying technique is important. And time between coats is important.

You can also sand the painted part with appropriately fine sandpaper, and paint it again, to get an even smoother finish.

We usually don’t have time to paint the robot…we’re too busy trying to make it work. There have been a few exceptions over the years.

We spray painted parts on 4329 for a couple of seasons. Generally our process was just to take all of the parts we finished at the end of the night, hit it with some spray paint and let them dry. When you come in the next day, your parts are ready.

By the end of the season you could definitely see some wear up close but from the stands the robot looked just as good as anyone else’s. We used the Rust-oleum stuff from Lowe’s, spent like 20 bucks overall with 0 prep work on the parts. If it takes time away that we could be building or assembling I don’t like it, so letting stuff dry overnight is the way to go in my opinion.

Scuff aluminum - 3m pads or sand paper. Wear gloves and wipe clean with acetone (alcohol will do but acetone cleans better). Apply a coat of self etching primer, rattle can will do. Apply your color coat after primer dries. The self etch primer bites into the surface and creates a bond between the aluminum and the paint.

Make sure to do in well ventilated area, preferably outside.

Considering your going to painting in January or February, paints with a fast drying time in a less than warm shop is a important consideration.

Stay far away from any Testers model paint, the cure times are excessive.

Automotive Primer and Color-match Paint (Duplicolor) dries much faster than most other paints.

If the objective is to have colored aluminum for the robot, you may want to consider anodizing instead of painting. Granted, this may not be within the typical team’s capability; however, you may be able to find plating houses that are willing do donate their capabilities to local teams.

In the Indianapolis area, Colors Incorporated has been contributing to our colorful competitions for a number of years. They are a much appreciated sponsor for a number of the local teams !!

I believe this was the post being referenced: https://www.chiefdelphi.com/forums/showpost.php?p=1058259&postcount=22

As other’s have noted, the process of deburr / light sand -> clean with acetone -> use enamel spray paint works really well. If possible, do it indoors in a well-ventilated environment away from other people not wearing respirators and where you are building the robot. We used to use the automotive garage/classroom next door with the exhaust ventilation fans turned on.

If you spray paint outdoors, the wind can blow dust and/or small bugs into the wet paint if you are not careful.

As someone who has anodized in their own team’s shop, I wouldn’t recommend it. Even we only did it once. And if the OP is worried about painting potentially taking days, then anodizing at a sponsor would likely be on that same time frame as the best case scenario.

There is a product company called DuraCoat, its most commonly used to paint firearms. It isn’t super cheap, but it works good. Sticks to almost anything, and there are hundreds of colors and patterns to pick.

On our team we are usually able to install powdercoated parts on the robot within an hour after they finish fabrication. Our typical timeline is as follows:

Sand aluminum part with RO sander at 120 grit - 7 minutes
Wipe part with acetone - 2 minutes
Hang parts on rack with bailing wire - 5 minutes
Coat parts with dual voltage eastwood powdercoating gun - 7 minutes
Place parts in oven for 20 minutes at 425 degrees - 25 minutes
Remove parts and let cool (often outside) - 10 minutes

We usually do this process as a production line and are able to powder coat and reassemble a mechanism within a 4 hour meeting.

The oven in our shop is big enough to fit most gusset and gearbox plates. Long sections of extrusion are baked in a file cabinet oven in a mentor’s garage. We really enjoy not having to wait overnight for paint to dry and also not needing to worry about VOC’s and storing spray paint in our shop. Finding a well ventilated warm area to work in the Michigan winter can be a challenge.

There’s kind of two ways to paint aluminium on your robot. You can do it the right way with lots of prep or the “wrong way” and just spray some paint on the parts as quickly as you can. With paint unlike powder or anodizing you’ll have to accept that it will get dinged and damaged. While doing it the wrong way will certainly be less durable maintaining a perfect paint job is a very hard thing to do even when done right. You can use similar color permanent markers to hide dings and scratches in the finish at competition.

Thankfully because robots are already so busy in appearance blemishes in the paint are hard to see. While we didn’t paint much of our robot this year the parts that did get painted were done the quick and dirty way and it held up fine.

One thing I might recommend if you do a lot of painting is to get a HVLP gun, even the $16 one from harbor freight is sufficient. You’ll save a lot of money on paint compared to spray cans, you can tint to any color you want and you get far less drips, runs and overspray. It’s just all around a easier, cleaner and more controllable process. The tradeoff is you need to keep it clean with solvent between coats but if your the kind of team that paints all it once I’d really strongly recommend it. After using one for a project recently I’m never going back to spray paint.

Sometimes looking outside the box pays off!

We drop off our parts after the present day’s meeting and pick them up before the next days meeting, Zero lost build time. I haven’t heard anything on this thread that even comes close.

Colors Incorporated - or ColorsInc - is an amazing sponsor in Indianapolis. With some looking it may be that other teams can locate similar services in other areas.

We’ve found success with this method but just keep in mind that your sandpaper doesn’t need to be large grit, anything above a polishing grit should work fine. The rougher you go the more rugged you finish will be.

Acetone has health and environmental issues. I would avoid it as a first choice. Soap and water works just as well. You want the surface clean and oil/grease free. Unless you are painting a lot, the hardware store rattle cans are the cheapest solution. Both cost and time wise. Another thought is to get a local body shop interested in what you are doing. They have way better paint and equipment to do a far better job at not a lot of cost to them.