Powder Coating Aluminum and other Cast Parts

If you’ve already jumped headfirst into the world of powder coating you’ve surely encountered some stubborn parts to coat. Cast aluminum parts can be one of the most fickle to powder coat. . On modern automobiles the majority of the bolt on parts (and even some of the major engine parts!) are cast aluminum. These cast aluminum parts can really dress up your engine bay once powder coated, but they can also be VERY difficult to get 100% clean when you try to powder coat them. The most difficult items to get a smooth finish when powder coating are the ones that have been exposed to oil and grease their entire lives. Cast aluminum parts are very porous and they tend to “soak up” the oil through the minuscule pores on the surface. This means wiping the surface quickly with a parts cleaner isn’t enough. If you take a few additional steps to prepare your cast aluminum part you can have a better chance of avoiding fisheyes, bubbles, etc. Below are the basic steps to take to get your cast aluminum parts to come out perfect every time!


1. Remove loose/heavy dirt and corrosion- The reasons here are obvious, powder coating is only as durable as the surface it has been sprayed over! Any loose corrosion or grease can be wiped off and so can the powder coating you put over it. I like to start by taking a wire brush and going over the entire part to remove and the heavier corrosion and dirt. I then spray the part with a heavy parts cleaner like Eastwood Chassis Kleen to wash off the residual grease and dirt. Another reason to take these steps first is to save your time with the media blaster AND save the media in a blast cabinet. If you just throw a super dirty part into the cabinet the grease and heavy dirt can eventually mix with the media and clog the blasting nozzle, requiring a media change in the cabinet.

2. Media Blast Parts- With the parts relatively clean to the touch I then move on to media blasting the parts. The type of blaster you use is dependant on a few things; what size compressor you have, how often you media blast, and the size of your parts. If you’re regularly blasting small to medium size parts a blast cabinet will be the most cost effective, while our small blast kit does not require a large compressor and doesn’t take up a lot of space in the workshop. If you plan to blast larger parts often a standup pressure blaster is a good investment as well. A good all-around media to use on cast parts is 60 or 90 grit Aluminum Oxide. The result will be a light silver finish that is VERY susceptible to dirty fingers, so make sure you wear rubber gloves when handling the parts from here! I also like to spray the part down with Afterblast to etch the parts and clean off any blasting residue.


3. Now you’re thinking your parts are plenty clean and ready for powder right? NOPE! There’s grease and oily residue hiding deep in the pores of cast aluminum parts that can only be “burnt” out by baking or a torch. The easiest way to get rid of the hidden contaminants is to pre-bake your part in the oven at a slightly higher temperature than your powder cures at for longer than your powder cure time. This will burn off the residue and it’s the best way to out gas a part so that you won’t have fish eyes or small bubbles on your cast parts after curing the powder. I’ve also used a small torch and run it over the part to burn off the excess residue, but you must be careful to monitor the heat of the part before applying the powder.


4. Applying Powder- Larger cast aluminum parts like transmission cases, wheels, cylinder heads, engine blocks, etc. can be difficult to get the current to pass through when powder coating a cold part and poor powder adhesion can be the result. You could make a “ground tree” and attach grounds clamps at numerous points on the part and link the grounds with wire to the main gun ground clamp, but if you need to spin the part when applying the powder you will have a mess of wires. I prefer instead to apply the powder immediately after I have pre-baked or outgassed the part in the oven. Hot-Flocking the powder onto the part allows the powder to melt almost instantly when applying it to the surface and it also helps powder get into tight areas where Faraday Cage effect would not allow powder to sit. When hot flocking the powder you want to make sure you move quick and that you closely monitor the heat of the part so you don’t have powder that is half and uncured next to each other. You also need to resist the temptation of going over an area too many times as build thickness is hard to monitor when hot flocking and you can actually RUN the powder (ask me how I know!) and when it flows out it will run and create large, rock hard bubbles or runs in the powder that have to be mechanically removed.


The great thing about powder coating cast aluminum parts (especially poor quality castings) is that the powder fills and builds nicely and will make a cast aluminum part look worlds better because it will fill minor pits and casting marks in a part leaving a nice deep, smooth finish. Once you’ve got this process down it becomes second nature, but it IS necessary to get the best results on cast aluminum parts! Cleanliness is next to godliness in the powder coating world for sure!



  1. Awesome. I do a lot of coating on boat parts at my house and have had trouble with parts that have encountered oil or fuel. This could be my ticket to perfection! Thanks!

  2. looks like we should almost always outgas the parts before coating them. It works for me.

  3. Thank You Your site has been very helpful for my projects not to mention your product which stand alone for value.

  4. I haven’t tried powder coating aluminum yet so for me this article is a good tutorial. Thanks for sharing

  5. Thanks. After heating to outgas do you wipe or clean the surface again before applying the powder?

  6. Does this process also apply to the extruded aluminum like boat windshield frames that have been pitted by salt water ?

  7. Can I damage an intake manifold by overheating it? Is 500 degrees too hot.
    Have an original 426 2X4 manifold.

  8. unfortunately, I learned this the old fashion way the school of hard knocks………………….

    Just love using the hot flocking with clears!

    you gave very good info for those that do not yet know!

  9. I have had parts powder coated by a shop in the past. Initially the parts looked beautiful but over time the coating began to bubble and come off. I assume the shop did not use any of your techniques when coating my intake manifold. Thanks for providing some of your insight to those of us who are non-professionals in coating!

  10. Generally, yes the temps are the same. The powder you use determines the temps that the parts are baked at.

  11. The powder you use determines the temps used to cure the powder, most aren’t at 500 degrees. The manifold should be able to handle any temps that powder coating require.

  12. Hi, Yes, we always suggest pre-baking parts to outgas any contaminants that may be locked just below the surface or in the pores of the metal.

  13. You could wipe clean with acetone or PRE, but the part should be very clean at this point if you have blasted and wiped it before already. The only reason I’d see a need would be if the part then sits for a while before you powder or if the heat baked out some visible oil or grease that’s now on the surface.

  14. Great information. How about cast potmetal, like old doorhandles, hood emblems, etc.
    What can do do for these with pits or blemishes?

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