Here is a powder coating infographic that covers the very basic steps of powder coating. This is the most basic of the basics, but it serves to show you what order the steps should go in. Go to this article to see a much more thorough explanation of the preparation steps: How to Prep for Powder Coating. Below the infographic, you will find links that expand each step of the process.
For more info on each of the steps listed above, you can find its corresponding article here on the site. Also check out the more thorough article, "How to Prep for Powder Coating."
Step 2: Clean your part.
Step 4: Sandblast your part - Sandblasting Pt 1, Sandblasting Pt 2 & Alternatives to Sandblasting
Step 5: Post- Sandblast Cleaning - Explained in Step 6.
Step 6: Mask your part if needed - Masking Pt 1 & Masking Pt 2
Step 7: Spray part with powder coat using a Powder Coating Gun.
Step 8: Bake part in an Oven for specified time.
Step 9 & 10 are pretty self-explanatory.
Stay tuned for the next article!
Currently, you go from Step 2, Disassemble & Clean to Step 3, Outgas. What if the item has a prior finish, like paint? Wouldn't you sandblast and blow-off first, degrease & clean, then Outgas? Are your steps assuming a bare metal part with no prior finish? Thanks and great work BTW!
ReplyDeleteHey Tom, There is supposed to be a large infographic picture on this page that further explains all of the steps but it seems there is an error and it is not displaying, I am sorry about that and will get it fixed asap.
DeleteTo expand on your question, sandblasting would be the next step after outgassing (step 4). You never want to sandblast a dirty part when prepping for powder coat. If you sandblast a dirty part, all of the greasy crud on the part will end in up in your sandblasting cabinet. It will contaminate your media and be redeposited on every part that goes through the cabinet after. Sandblasting works great to clean off dry things like paint or other previous coatings, but when you contaminate the media with something wet like grease or oil, your parts will not come out clean, there will be grease/oil deposits which will be difficult to clean off.
So, just to recap:
1. Clean part
2. Outgas
3. Sandblast (nothing dirty touches the part after this point and only handle it with clean gloves)
4. Blow off all dust with air compressor (this air needs to be clean and dry too)
5. Mask (if necessary)
6. Powder coat
Hopefully that answers your question, let me know if you have any more questions. Thanks for being a reader!
Thanks Sean. So just to clarify, if the part has a prior finish (i.e. paint) you outgas with the finish on it after you clean the part? The question then boils down to, does a part still outgas even with an existing painted finish?
DeleteWell it would depend on what type of paint or coating is on the part. 99% of the parts I do have paint that is in terrible condition and flaking off. Most paint is removed by the pressure washer cleaning step. Spray paint does not stand a chance at blocking outgassing either. If your part does have a nice solid powder coating or other durable coating, then the correct thing to do would be to strip the coating off first, then clean, then outgas.
DeleteWhen do I add clear coat or a second coat of color? Do I add after the first coat is cured?
ReplyDeleteI actually have the exact same question lol. Would be good to know.
DeleteThis is a topic that I will definitely explain in complete detail in several articles, but I will explain the process briefly to answer your question.
DeleteThere are two procedures for multi-coats and they depend on what type of powder coat you are using. If you are using a chrome like powder coat, you would do the chrome first and complete the bake cycle 100%. Then you would let the part cool completely to room temperature, and shoot your 2nd coat whether that be clear or a translucent candy. You would then put the part back into the oven and bake it again. If you do not cure the chrome 100% before starting the next coat, the coating will not look the way that it should. The chrome will look like it has a texture.
If you are using a standard color powder coat (red, black, white, blue, ect..) and wish to add a clear coat to it, the process is very similar to what I explained above except...
After you shoot your 1st coat, you will put the part in the oven but you will only cure it about 60 to 75%. Meaning if the bake schedule calls for 10 minutes @ 400 degrees you would only bake the part for 6 to 7 minutes. You then remove the part from the oven and let it cool completely. You can then spray the 2nd coat and put it in the oven for the 2nd coats full bake schedule. Lets say the 2nd coat is a clear coat that also bakes for 10 minutes @ 400 degrees. You would put the part in for the full 10 minutes. This method allows the 2 coats to interlock and chemically adhere to each other. This will give a much stronger bond between the 2 coats and will lessen the changes of delamination (where the 2nd coat peels off of the 1st coat).
Just like always, make sure you do not start your timers until the part reaches the proper cure temp. If the bake schedule is 10 minutes @400 degrees, you must wait until the part reaches 400 degrees to start the 10 minute timer.
I hope that helps out and I will definitely explain it more in detail when I get a chance to write some more articles. Should be writing again this month so make sure to check back. Thanks for reading. Keep the questions coming!
Hi Sean,
ReplyDeleteThanks for this site and the work you put in. Just one question. Have you ever tried coating MDF? I heard there are some lover temperature powders or even UV curing ones but I can't find a place to buy them. Any extra info regarding wood/MDF powder coating will be well received.
Keep up the good work and thanks again.
I have yet to coat mdf myself but it has been done and currently companies are working on lower temp curing powders for applications such as these. There are some out there on the market, but they usually aren't listed on the well known powder sites. The best way to find out about these powders is to directly contact the powder manufactures. Example: PPG, Tiger Drylac, Sherwin Williams, ect. I would try PPG first, here is their contact page: http://www.ppg.com/coatings/industrial/Pages/contactus.aspx . Just a word of caution though, these companies do not sell by the pound, they like to sell in bulk.
DeleteI've scoured around but I have not been able to find my answer.
ReplyDelete1) I'm wondering when you hang your part to be powder coated does it matter where the part is hung from? I'm thinking along the lines of paint where if you have the hanger on a part that needs coverage the hanger will obstruct the coating from being applied. Does this apply to powder coating in the same way it would to painting?
2) If I am powdering a part like a rim is it necessary to have coverage on the inner well of the rim as to achieve continuoius coverage of powder or can you leave a bare spot between the bead portions? Does this alter the stability/durability of the powder coating where the bare metal and powder starts?
Thanks again,
Andrew.
1. Just like painting, there will be a hook mark when shooting powder. However, due to the powders ability to wrap around parts, the hook mark will be much less noticeable. If I can, I always try to hang a part from an area that will be masked off anyways, like a bolt hole. If I am coating a wheel, I will use an eye bolt through the valve stem hole with a nut and washer. This way there is visible hook mark.
Delete2. It is not 100% necessary to coat the entire barrel of the rim and as long as you coat past bead, there should not be any durability issues. However, there are some scenarios where corrosion could start inside the barrel and eventually work its way underneath the powder. If you are powder coating for customers, the correct thing to do is to coat the entire rim. I always coat the entire wheel including the barrel mostly because it looks more professional. The only part of a wheel I do not coat is the hub.
This may or not be the reason you have a concern about this.. The very first set of wheels I coated, I had to figure out how to handle each rim while inserting them into a household oven for individual curing. The wheels would not fit in the oven hanging, so this is what I did to coat the entire rim in one shot.
1. Pull out the oven rack and set it on a table with a metal cylinder in the middle.
2. Put the wheel face down on the metal cylinder.
3. Coat just the inside back side of the wheel.
4. Grab the uncoated sides of the wheel with gloved hands and turn it over so the masked hub is now sitting on the metal cylinder.
5. Proceed to coat the sides and face of the wheel.
6. Carefully lift the rack and slide it in the oven with the wheel balanced on the metal cylinder.
(I bent the end of my rack to be flat so I no longer needed to tilt the rack to slide it in the oven).
This way, the entire wheel can be coated and cured in one shot and you can still coat the barrel with no issues. Again, that may or may not be your concern but it may be useful for you.
In between step 6 and 7 do you preheat the part before coating with powder ?
ReplyDeleteNo, I always avoid preheating parts if I can. Preheating parts often leads to way to much powder applied to the part. If you aiding powder attraction by preheating the part, you would be better off setting up a dedicated grounding rod if you haven't already. Check out the article on this site titled "How to Properly Ground your Parts"
Deletei just wanna ask? i'm a newbie. does it needs to be heat the stuff in 200degree before spraying the powder coat?
ReplyDeleteNo, you do not need to preheat the part at all before powder coating unless you are doing so to outgas cast metal parts. The only reason pre-heating the part is done is to overcome faraday cage issues with cheaper powder coating guns. It should only be done if aboslutely needed but it should not be apart of your normal procedure.
Delete