So, when I last left off the bottle opener project (my previous Instructable), you'll remember that we left the natural patina that develops from leaving medium carbon steel to weather in the elements. While certainly this makes for quite an attractive appearance of the final product, sometimes it's nice to add some color to the project.
So I decided to powdercoat one of my bottle openers. Now, powdercoating is not a difficult process - at all - but it does require some skill and finesse to get a good final product.
For those of you who are unfamiliar with what powdercoating is, it amounts to blowing an electrically charged powder (hence powdercoating) onto a grounded object (typically metal of some sort) and then baking it on. When done correctly, the result is a pretty durable, and quite attractive finish.
So before we get started in the actual "how-to" steps, let's talk a bit about what you'll need for this project.
I should also add that while you can complete this project in your back yard (assuming you have a powdercoating gun), it helps to have a clean, dedicated workspace and the proper tools and resources designed for actually performing a powdercoating process at a professional or semi-professional level. For example, I made this at Techshop. You can find some pretty specialized tools there, and certainly everything you need for this project.
So, without further ado...
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Step 1: What You'll Need...
Bottle opener (in case you missed the previous Instructable, check it out here)
Eye and ear protection
Step 2: Grind Down Burrs, Clean Up Grinds.
Before moving forward, make sure that the bottle opener you plan to powdercoat doesn't have any sharp edges or burrs that you missed when you first made it. The reason is simple... wel, there are two reasons, actually. First, remember that this bottle opener will likely be in your pocket or some other place that will be convenient for you to grab it when you need it. The last thing you want is to hurt yourself when you aren't paying attention. Second, the powdercoat on sharp edges will tend to be worn down first, leaving gaps in your powdercoat. Remember that since we're not too terribly concerned about the natural patina (since we're covering it up with the powdercoat), it's ok to remove some of the patina with the grinder if necessary.
My favorite tool for this has to be the 20" disc grinder. I cannot express to you how great this tool is for all manner of grinding tasks. Remember to always wear eye protection when completing these projects, but be extra careful when operating such machines as the disc grinder.
Step 3: Prepping Your Work...
When powdercoating, it's important to prepare the surface onto which the powdercoat will adhere, removing all surface rust, moisture, dirt, oil, or anything else that may interfere with the finish. The next thing we do is to sandblast the piece we wish to powdercoat.
Sandblasting is essentially a process whereby we use a pneumatic gun that fires sand (or other abrasive particulate medium) under pressure, and is great for stripping paint, rust, or natural patinas from pretty much anything. If you can fit it into the sandblasting cabinet, chances are, you can sandblast it.
Now, be careful when sandblasting. Due to the expellant's particulate nature, it's important to properly ventilate both the sandblasting cabinet and the work area.
A good sandblasting cabinet will be completely enclosed and will have gloves that allow for handling the work to be sandblasted to be handled while remaining safely outside the cabinet. It will also have a window through which you can see what you're doing.
When prepping the cabinet for sandblasting, make sure you have a piece of stock upon which you can place your work so that you can pick it up easily. The rubber gloves make it difficult to pick up flat pieces of work, so keep that in mind when preparing yourself.
Grab the piece to be sandblasted in one hand and the sandblasting gun in the other, and engage the gun. Some sandblasting guns use a foot pedal, like the one in this Instructable, whereas some operate with a trigger mechanism. Either way, just make sure you know how to use it prior to starting your project.
As you're sandblasting your work, take care to evenly sandblast it. You typically don't want to have an uneven finish, as it will just undermine your attempts at powdercoating.
After you've used the gun to sandblast, give the cabinet a minute or two to fully expunge the abrasive medium from the air. If you don't, and you breathe in the air inside the cabinet, it can lead to respiratory problems, both acute and chronic. So BE CAREFUL!
Step 4: Clean Your Work!
As I mentioned before, powdercoating requires one's work to be very clean, otherwise the finish will suffer. Any moisture, sand (from the sandblasting process), or even lint from handling your work can and will negatively affect your powdercoat. Therefore, before the cleaning step, make sure you are weaing your rubber gloves. This will prevent any oils from your hands from marring the soon-to-be exceptionally clean work piece.
Take your bottle opener over to the sink and aggressively brush it, using warm water and some sort of heavy duty soap. Once you have washed it, wash it again, repeating the aggressive approach while making sure nothing but your gloved hands touch the bottle opener.
After you've washed it and shaken it dry, inspect your work to make sure you properly sandblasted your bottle opener. Assuming you did, wash your part again. I know this seems like overkill, and a bit comical, but believe me... you will thank me later.
Now that you've cleaned and inspected your work, then cleaned it again for good measure, take your bottle opener to the powdercoating room. Carefully hang your work from a piece of wire (preferably the conductive one you plan to use to hold your bottle opener up for the actual powdercoating procedure) inside the powdercoating oven and then close the oven. Preheat the oven to the appropriate temperature recommended for your particular powder. This will both prep the piece for accepting the powder as well as drying the piece prior to that step.
Step 5: Prepping the Powdercoating Cabinet.
While your bottle opener is warming up and drying out in the oven, prepare the powdercoating gun. Check the pressure as well as the voltage to ensure that everything is set to the manufacturer's recommended parameters for best results.
Before attaching your powder bottle to the gun, make sure the gun is clean and functional by engaging the gun and making sure the coupling as well as the gun itself is clean and absent any powder from previous operations. Once you know the gun is clean, attach your powder bottle to the gun and test the gun to make sure it's properly feeding powder to the gun. Just pull the trigger on the gun and watch for a light misting of the powder. If you see it, you're golden. If not, repeat the steps above and make sure you have a clean gun.
After about 10-15 minutes of baking, your bottle opener should be sufficiently dry and warm to accept the powder. But just to be sure, grab the infrared thermometer and turn it on. Open the oven and take a reading on your bottle opener. It may take a few seconds to get a reading, but don't worry. That's perfectly normal. You're looking for a temperature ON YOUR WORK at or very close to the optimal temperature for your particular powder. What's important is NOT the temperature of the oven, per se, but rather the temperature of your work. Just in case, take a couple of readings. So long as you're not exceeding recommended temperatures for your powder, you're fine if your piece is a little warmer (+/- 25 degrees or so).
Once you're satisfied that your bottle opener has achieved sufficient temperature, put on the welding gloves (or other heat-resistant hand protection) and carefully remove your bottle opener. Walk to the powdercoating booth and hang the conductive wire from the ground lead inside the cabinet.
Now, you're ready to actually powdercoat.
Step 6: Finally, Powdercoating Your Piece!
As soon as you have hung your bottle opener from the ground in the powdercoating cabinet, put on your ear protection, then turn on the ventilation system in the cabinet.
Grab your powdercoating gun and point it towards your work. Start the flow of powder, and make sure you get an even coat of powder. Don't make it too heavy, as it will cause an "orange peel" effect in your finish. Make sure you get sufficient coverage, as too little powder will make for a less than pro look.
Also keep in mind that the wire by which you're hanging your bottle opener may impede complete coverage. In this case, you make have to move your piece around to get complete coverage.
Since you preheated your piece, you should already start to see the powder take on a more liquid appearance. this is what you want. It will help to ensure a better finish.
As soon as you're done shooting your bottle opener, holster the powdercoating gun and quickly (but CAREFULLY!) move the bottle opener (still hanging from its wire) back to the oven so that you can bake the finish properly. Close the ovenm then go turn off the ventilation in the powdercoating cabinet.
Typically, it takes 10-15 minutes for most powders to properly bake. After 10 minutes or so, open up the oven and inspect your work. Also tae a few seconds to test the surface temperature of the bottle opener with the infrared thermometer. That is the best indication of whether your piece is properly baked or not.
Keep in mind, you can overbake your work, just as you can underbake it. So practice this. Keep in mind that this is a skill, and not something perfected in on attempt.
If you're unhappy with the result, you have a couple of options. Sandblast the powdercoat off and start over, or reshoot the piece and rebake it. In fact, there are some interesting techniques for using multiple colors, or even a clear coat to protect your color coat.
After you're done, make sure you clean up your workspace. Cleanliness and safety go hand-in-hand.
I hope you enjoyed this Instructable!