1
Powder Coating: HOWTO Fri Nov 29, 2013 12:54 am
jjefferies
Life time member
An aside/explanation for doing this: My wife once told me that I'm a prime candidate for the CABoA (Cheap Ass Ba****ds of America). 
Not true. I just like a job done right for a reasonable price. Right now I'm restoring a '90 K75 for her use and modifying it as a cafe racer. I was willing to pay USD $120 to have the frame powder coated. But when they sand blasted the hell out of where the head bearings fit as well as the fork lock. Ok, it looked pretty but man was I worried that the bearing would be sloppy. And all would have taken to do it right was a little attention before the sand blasting. Then when I was quoted a price of $150 to do the fork lowers and the valve covers. Ach!! I started looking for alternative approaches.
As of this date, 11/28/2013 you can buy an el cheapo Chinese made powder coat spray gun with the electrostatic generator in the US from Harbor Freight, i.e. Chicago Electric Tools for USD $60.
http://www.harborfreight.com/catalogsearch/result?q=powder+coat
Powder coating material ranges in price from USD $5.00/lb(cheap Indian made stuff) to $30/lb(high grade in any color). In addition you need an air compressor (small) and most critically an oven capable of reaching 400 degrees F or 204 degrees Celsius. It is the oven that determines how large a piece you can powder coat. There are a number of youtube videos on powder coating and I'll put links to some of those at the bottom of this. My intent is to basically talk this process up to fellow riders and what some of the tradeoffs are. In the past I have used spray paint with hardeners, very poisonous, requiring breathing apparatus. Powder coating reportedly (according to the industry) is relatively environmentally friendly and does not require the same degree of protection. However it does stink during the curing, baking, phase and I personally do not like to breath the fumes given off. So doing that part outside makes a lot of sense to me. When actually spraying the powder you are working with a very fine dust and should protect yourself from breathing it. All that I've read says the powder is not poisonous but I ain't that trusting so I do use a simple nose/mouth filter.
Powder Coating material: There is a wide range of materials available. Harbor Freight sells the cheap Indian made stuff in three colors (white, red, black(sort of greyish)). This is rather crude stuff and requires a full 400F for 15 minutes to cure. On the other hand you can get very high grade material in just about every color and shade you can imagine in 1 lb quantities. One advantage of the more expensive powders is that they don't have to be heated to such a high temperature but can be baked as low as 320F. Here take a look at the colors possible. And that includes clear coats and candy as well. Allpowder is just one of several suppliers available online:
http://allpowderpaints.com/products.html
The oven: As mentioned this is what determines how large a piece you can do. Obviously a whole m/c frame requires a good size oven. And you can see some of these large ovens depicted in the youtube videos. But some people have made do with toaster ovens for small parts. For my part after reading about other amatuer's experiments making an oven I decided to go with a regular electric kitchen oven. They have temperature regulation, built-in lights, and timers. All the goodies that I saw people working hard to replicate. ***CAUTION*** once you have used an oven in powder coating you CANNOT EVER use it again for food, human or animal. So don't even consider trying this with your household oven. Even once. Further what you want is an ELECTRIC oven. Gas heated ovens have open flames which can give rise to fire hazards when the parts are being baked. What I did was to go to Craigslist. There I found some folks who were throwing out an electric built-in oven because it was having problems. They obviously had decided it was more cost effective for them to replace it and they were offering it as scrap metal. So I called and they said they would leave it by the curb and I should come get it. ONE CAUTION: if you go this route, make sure you carry along a really thick pair of gloves to handle the thing. Old built-in ovens have a lot of sharp edges and it took a number of weeks to grow back some skin on my hand. But I muscled it into the back of my wife's pickup and with my bloody hand took it home. It required two bottles of easy-off oven cleaner to get through the encrusted food stuffs. But under the rough exterior was a working oven with two heater elements, a air circulation system, built-in lights and timers. It was the stove top elements that had failed. Once I had cleaned it I mounted it on a wooden roll-around. As I indicated while the fumes are not listed as poisonous I wouldn't like to breath them and the ability to roll the entire operation out of the garage into the open air was desirable I felt. So some rusted scrap shelving hit with rustoleoum paint and I had my powder coating station. Here are two photos from the front and back:
https://i.servimg.com/u/f57/18/43/58/50/img_1510.jpg
https://i.servimg.com/u/f57/18/43/58/50/img_1511.jpg
A couple of things about the station, you can see the box containing the powder coating gun on the back side shelf. Down below is air compressor. For best operation you need a steady supply of air and I included an air reservoir, not seen, also available from Harbor Freight for $25. On top is the remains of the stove top (the oven and stove top heaters were two separate entities) which makes a nice catch all. On the photo of the front side you can see some of the stains left from powder getting knocked off the items as I put them in the oven. Also in this photo is the cardboard box which I use to shoot the parts in. It keeps the wind off while I am spraying/powdering the item. Note also the extended 220V line used to connect the stove to a power outlet of the kind used by dryers or ovens.
METAL PREPARATION: Obviously your item to be coated must be clean of all rust, grease etc. If you have access to a bead blaster that's the best choice. I didn't, so I used a bench grinder with a wire brush mounted to take off paint, rust and everything else. This works but you really need to respect your eyes and use a really good shield in addition to glasses. Wire brushes have a tendency to throw out broken metal wires which will go through heavy cardboard, wood, your clothes and your eyes.
Shooting/spraying your metal object: If you can use a spray/rattle can then you can shoot powder coating. Other than a couple of tricks it really is forgiving. And if you mess it up you just shake off the powder and reuse it.
First this system uses air 10-30 lbs/sq in for the spray gun. In addition there is an electrostatic generator, a small box with an 110 AC plug, a foot pedal, and two wires. One wire goes to the spray gun and the other to the item being coated. From others I learned it is useful to have a small booth to shoot in. Keeps the wind and bugs out and the excess powder in where you can sweep it up for reuse. The cardboard box seen in the front photo above is what I came up with. It has two copper wires running across the top. The item being coated is hung from one of these by another piece of copper wire. The ground wire from the electrostatic generating box is connected to the two copper wires running across the top of the box. When you want to begin spraying you have to press the hand switch on the gun (turns on the air) and press the foot pedal (turns on the electrostatic generator).
DANGER WARNING:: **** when you are spraying and the electrostatic generator is operating it is not unusual to touch or get the gun so close to the item being sprayed that you get a spark. This is common and doesn't seem to affect the spray gun's operation. But IF THE BOX IS FULL OF AIRBORNE POWDER the spark can set off a flash explosion ******. I've had this happen. It is possible for this to start a fire or cause a burn. STRONGLY RECOMMEND PROTECTIVE GLASSES. In my short experience this is the primary safety concern I've encountered.
TRICKS: I mentioned tricks, there are several. If you are shooting into a space such as a corner or where two surfaces join you will find you have difficulty getting the proper amount of powder in. This is due to the combined electrostatic charge from the two surfaces joining to push the powder away. Sometimes with small parts it serves to tilt the part so it is below and shoot downward using gravity as well as the electrostatic phenomena.
Also it is possible to reshoot an item if you find a place where the powder was too thin and you didn't catch it before baking.
Another tricky bit is to move the part from the spraying area into the oven. I found a couple of super long nosed pliers very useful. And a bunch of copper wire hooks that you can hang items being coated from are essential.
Lumps in the powder. The better grades of powder will be finer and have fewer lumps. The lumps come from the powder having being heated during storage or transit. Sun on a delivery truck can be the cause. If you get some material like this a flour sifter will fix the problem and sieve out any lumps which cannot be rendered back into powder.
BAKING: is just what it sounds like. You turn on the oven and get it to the right temperature. In the meantime you can be spraying your item. Once the oven is at the correct temperature, usually the baking temperature and how long to bake are on the powder's container, you put the powder sprayed item in hanging from a hook or on one of the oven's shelves and let it bake for the recommended time. Checking of course just like you would with brownies. At the end of the time pull the item out and hang it up to cool. I found that doing one item at a time worked well enough with this home made system. Timing was 10-20 minutes and if I worked it well that was long enough to shoot the next piece, get back and pull the current item out of the oven and put the next one in. Of course YMMV. The oven I rescued is 17"x17"x21" and I easily fit a fork lower or a valve cover in. With 400F as a max temperature I feel you can do most steel and aluminum. Not sure about parts that have been brazed but that's on my list to experiment with. Sadly fiberglass and plastic are definitely out.
That's it for the moment. I'm supposed to be doing other things right now. Hope to come back and annotate with additional photos and links.
PPS: Recently found that the "Tech Shop" http://techshop.ws/ has a very nice program for former military, a free membership and funds for a number of classes. Took two classes in sheet metal and one each in MIG and TIG welding. Sweet. Then found that they have a walk-in powder coating oven with all the best ventilation, Super Sweet. So if you are in the S.F. Bay area or anywhere else they have their studios/school suggest you look them over.
Not true. I just like a job done right for a reasonable price. Right now I'm restoring a '90 K75 for her use and modifying it as a cafe racer. I was willing to pay USD $120 to have the frame powder coated. But when they sand blasted the hell out of where the head bearings fit as well as the fork lock. Ok, it looked pretty but man was I worried that the bearing would be sloppy. And all would have taken to do it right was a little attention before the sand blasting. Then when I was quoted a price of $150 to do the fork lowers and the valve covers. Ach!! I started looking for alternative approaches. As of this date, 11/28/2013 you can buy an el cheapo Chinese made powder coat spray gun with the electrostatic generator in the US from Harbor Freight, i.e. Chicago Electric Tools for USD $60.
http://www.harborfreight.com/catalogsearch/result?q=powder+coat
Powder coating material ranges in price from USD $5.00/lb(cheap Indian made stuff) to $30/lb(high grade in any color). In addition you need an air compressor (small) and most critically an oven capable of reaching 400 degrees F or 204 degrees Celsius. It is the oven that determines how large a piece you can powder coat. There are a number of youtube videos on powder coating and I'll put links to some of those at the bottom of this. My intent is to basically talk this process up to fellow riders and what some of the tradeoffs are. In the past I have used spray paint with hardeners, very poisonous, requiring breathing apparatus. Powder coating reportedly (according to the industry) is relatively environmentally friendly and does not require the same degree of protection. However it does stink during the curing, baking, phase and I personally do not like to breath the fumes given off. So doing that part outside makes a lot of sense to me. When actually spraying the powder you are working with a very fine dust and should protect yourself from breathing it. All that I've read says the powder is not poisonous but I ain't that trusting so I do use a simple nose/mouth filter.
Powder Coating material: There is a wide range of materials available. Harbor Freight sells the cheap Indian made stuff in three colors (white, red, black(sort of greyish)). This is rather crude stuff and requires a full 400F for 15 minutes to cure. On the other hand you can get very high grade material in just about every color and shade you can imagine in 1 lb quantities. One advantage of the more expensive powders is that they don't have to be heated to such a high temperature but can be baked as low as 320F. Here take a look at the colors possible. And that includes clear coats and candy as well. Allpowder is just one of several suppliers available online:
http://allpowderpaints.com/products.html
The oven: As mentioned this is what determines how large a piece you can do. Obviously a whole m/c frame requires a good size oven. And you can see some of these large ovens depicted in the youtube videos. But some people have made do with toaster ovens for small parts. For my part after reading about other amatuer's experiments making an oven I decided to go with a regular electric kitchen oven. They have temperature regulation, built-in lights, and timers. All the goodies that I saw people working hard to replicate. ***CAUTION*** once you have used an oven in powder coating you CANNOT EVER use it again for food, human or animal. So don't even consider trying this with your household oven. Even once. Further what you want is an ELECTRIC oven. Gas heated ovens have open flames which can give rise to fire hazards when the parts are being baked. What I did was to go to Craigslist. There I found some folks who were throwing out an electric built-in oven because it was having problems. They obviously had decided it was more cost effective for them to replace it and they were offering it as scrap metal. So I called and they said they would leave it by the curb and I should come get it. ONE CAUTION: if you go this route, make sure you carry along a really thick pair of gloves to handle the thing. Old built-in ovens have a lot of sharp edges and it took a number of weeks to grow back some skin on my hand. But I muscled it into the back of my wife's pickup and with my bloody hand took it home. It required two bottles of easy-off oven cleaner to get through the encrusted food stuffs. But under the rough exterior was a working oven with two heater elements, a air circulation system, built-in lights and timers. It was the stove top elements that had failed. Once I had cleaned it I mounted it on a wooden roll-around. As I indicated while the fumes are not listed as poisonous I wouldn't like to breath them and the ability to roll the entire operation out of the garage into the open air was desirable I felt. So some rusted scrap shelving hit with rustoleoum paint and I had my powder coating station. Here are two photos from the front and back:
https://i.servimg.com/u/f57/18/43/58/50/img_1510.jpg
https://i.servimg.com/u/f57/18/43/58/50/img_1511.jpg
A couple of things about the station, you can see the box containing the powder coating gun on the back side shelf. Down below is air compressor. For best operation you need a steady supply of air and I included an air reservoir, not seen, also available from Harbor Freight for $25. On top is the remains of the stove top (the oven and stove top heaters were two separate entities) which makes a nice catch all. On the photo of the front side you can see some of the stains left from powder getting knocked off the items as I put them in the oven. Also in this photo is the cardboard box which I use to shoot the parts in. It keeps the wind off while I am spraying/powdering the item. Note also the extended 220V line used to connect the stove to a power outlet of the kind used by dryers or ovens.
METAL PREPARATION: Obviously your item to be coated must be clean of all rust, grease etc. If you have access to a bead blaster that's the best choice. I didn't, so I used a bench grinder with a wire brush mounted to take off paint, rust and everything else. This works but you really need to respect your eyes and use a really good shield in addition to glasses. Wire brushes have a tendency to throw out broken metal wires which will go through heavy cardboard, wood, your clothes and your eyes.
Shooting/spraying your metal object: If you can use a spray/rattle can then you can shoot powder coating. Other than a couple of tricks it really is forgiving. And if you mess it up you just shake off the powder and reuse it.
First this system uses air 10-30 lbs/sq in for the spray gun. In addition there is an electrostatic generator, a small box with an 110 AC plug, a foot pedal, and two wires. One wire goes to the spray gun and the other to the item being coated. From others I learned it is useful to have a small booth to shoot in. Keeps the wind and bugs out and the excess powder in where you can sweep it up for reuse. The cardboard box seen in the front photo above is what I came up with. It has two copper wires running across the top. The item being coated is hung from one of these by another piece of copper wire. The ground wire from the electrostatic generating box is connected to the two copper wires running across the top of the box. When you want to begin spraying you have to press the hand switch on the gun (turns on the air) and press the foot pedal (turns on the electrostatic generator).
DANGER WARNING:: **** when you are spraying and the electrostatic generator is operating it is not unusual to touch or get the gun so close to the item being sprayed that you get a spark. This is common and doesn't seem to affect the spray gun's operation. But IF THE BOX IS FULL OF AIRBORNE POWDER the spark can set off a flash explosion ******. I've had this happen. It is possible for this to start a fire or cause a burn. STRONGLY RECOMMEND PROTECTIVE GLASSES. In my short experience this is the primary safety concern I've encountered.
TRICKS: I mentioned tricks, there are several. If you are shooting into a space such as a corner or where two surfaces join you will find you have difficulty getting the proper amount of powder in. This is due to the combined electrostatic charge from the two surfaces joining to push the powder away. Sometimes with small parts it serves to tilt the part so it is below and shoot downward using gravity as well as the electrostatic phenomena.
Also it is possible to reshoot an item if you find a place where the powder was too thin and you didn't catch it before baking.
Another tricky bit is to move the part from the spraying area into the oven. I found a couple of super long nosed pliers very useful. And a bunch of copper wire hooks that you can hang items being coated from are essential.
Lumps in the powder. The better grades of powder will be finer and have fewer lumps. The lumps come from the powder having being heated during storage or transit. Sun on a delivery truck can be the cause. If you get some material like this a flour sifter will fix the problem and sieve out any lumps which cannot be rendered back into powder.
BAKING: is just what it sounds like. You turn on the oven and get it to the right temperature. In the meantime you can be spraying your item. Once the oven is at the correct temperature, usually the baking temperature and how long to bake are on the powder's container, you put the powder sprayed item in hanging from a hook or on one of the oven's shelves and let it bake for the recommended time. Checking of course just like you would with brownies. At the end of the time pull the item out and hang it up to cool. I found that doing one item at a time worked well enough with this home made system. Timing was 10-20 minutes and if I worked it well that was long enough to shoot the next piece, get back and pull the current item out of the oven and put the next one in. Of course YMMV. The oven I rescued is 17"x17"x21" and I easily fit a fork lower or a valve cover in. With 400F as a max temperature I feel you can do most steel and aluminum. Not sure about parts that have been brazed but that's on my list to experiment with. Sadly fiberglass and plastic are definitely out.
That's it for the moment. I'm supposed to be doing other things right now. Hope to come back and annotate with additional photos and links.
PPS: Recently found that the "Tech Shop" http://techshop.ws/ has a very nice program for former military, a free membership and funds for a number of classes. Took two classes in sheet metal and one each in MIG and TIG welding. Sweet. Then found that they have a walk-in powder coating oven with all the best ventilation, Super Sweet. So if you are in the S.F. Bay area or anywhere else they have their studios/school suggest you look them over.
Last edited by jjefferies on Tue Apr 15, 2014 2:57 pm; edited 5 times in total (Reason for editing : I forgot the baking process and wanted to clean it up a bit)
