Powder Coating can be a superior alternative to paint. However its not as easy as popping the top and spraying whatever you feel like. Its a multistep process that must be done correctly to get the best results.
Curious to see what Powder Coating was all about, we spent a morning out at One Works Powder Coating to have Andrew Paulson show us the ropes. According to Andrew, one of the most important steps in getting the best results is in the prepping. This can be 90% of the costs of the whole job. He suggested talking to your local shop first to see if doing some of the prep work yourself will save some money. Some shops will and some shops wont but it doesn't hurt to ask.
|Basically the prep work boils down to getting the metal as clean as possible before it gets even close to the powder. One method is to sandblast the metal clean. For small parts, using a DA sander or even hand sanding will also work. Following the rough cleaning, the part will then need to be wiped off with either Acetone or Phosphoric Acid. This will remove the leftover oils and anything else that might get in the way of the bonding process.||
|Once the part is completely clean, its time for the powder. Smaller, thinner parts can be sprayed while cold. Thicker parts and certain types of metals such as cast iron need to be preheated. The thicker parts need it so that it can get up to the needed temperature during the baking process. Metals like cast iron need it so the metal has a chance to outgas before it gets sprayed. Not getting all of the gases out or not getting the entire part up to the needed temperature can cause hazing, orange peel, and under cured parts.|
|One of the best ways to spray the part is to hang it from a rack in a clean exhausted environment. Just like a good paint job. But unlike paint, powder goes on totally different. The powder itself is literally a powder that has the look and feel close to talcum powder. Its pumped up and aerated and shot out of a spray gun much like paint. However unlike paint, you cannot get too much powder on a non flat surface. This is done in how the powder is stuck onto the metal surface.|
|At the tip of the spray gun is an electrode that can be charged up 100,000 volts depending on the application. The metal that is being sprayed is grounded. The created a like "static cling" that causes the powder to stick. If the powder becomes too thick, it simply falls off. You can get a covering between 2 to 4 mils thick this way. Preheating the metal can get you up to around 10 mils of thickness. The static charge also helps the powder to flow during the spraying process covering the entire surface more or less evenly.|
|The final step is the baking process. Here, we have the use of Andrew's oven which is a nice size at 7' by 7' by 10'. Plenty big to get most things. Andrew likes to set his oven at 400 degrees. How long its kept in the oven depends on the thickness of the metal and what kind of powder is being used.||
|The baking process flows out the powder and causes it chemically react to bond to itself and to the surface. One of the biggest fails of powder coating is not letting the part bake long enough. Baking it too short can cause it to look good but not completely bond. This will cause it to flake off pretty fast. A part can be put back in to finish baking but cannot be "patched" as the fresh powder will not bond to the already partially backed powder. You can see where we purposely pulled it out too early and were able to cause it to flake off.|
|If everything goes correctly, you now have a nice finish like the one here. Our example part was something laying around the shop and it received a nice coat of gloss black. We put it back in for the time needed after the flaking off example and it looks great. According to Andrew, a good powder coat can yield a covering that is 2 to 10 times as strong as compared to paint. Depending on your application, this might be the way to go for you.|
|Some safety precautions need to be taken doing
this type of work. A breather mask should be worn whenever applying powder
coat so it doesn't coat your lungs. Also the baking process can heat parts
up pretty hot. This oven is at 400 degrees. Don't get stuck inside!