Anyone familiar with electrostatic painting?

[John Reynolds]

Anyone familiar with electrostatic painting? Using an electrical charge to attract the paint onto a metal surface? <br />I recall several years ago while I was in the military there was a contractor hired by my unit to paint some old metal office/shop furniture. The furniture was gray, and was going to be repainted gray. Using an ordinary basic air spray gun, he took an automotive battery charger, attached one clamp to the furniture, and the other to his metal spray gun. The paint mist was attracted to the furniture like magic. He'd squirt out a cloud, and it would suck up all around the work. He would spray at one side of a table leg, and the paint would float past it, then come back around and stick to the back side of the leg. <br />I'm thinking of trying that this weekend when I paint my motor. What do you guys think?

 

[Hooty]

Re: Anyone familiar with electrostatic painting?

I'm familiar with electrostatic painting but I thought it was a little more involved than a spraygun and battery charger. Give it a try and let us know what you find.<br /><br />c/6<br /><br />Hooty

 

[Hooty]

Re: Anyone familiar with electrostatic painting?

Here's what I found real quick.<br /><br />Electrostatic Painting is the Way to Go<br />Electrostatic painting, also known as "powder coating," uses the principal of "opposites attract" to create a uniform and durable finish on metal and some plastics without the sags, runs, drips and bubbles which can occur with traditional liquid paints. It's used on many plastics and every kind of metal. <br /><br />Electrostatic painting process is simple in concept and operation. Dry powder comprised of resins and pigments is pneumatically fed from a supply reservoir to a spray gun where a low amperage, high voltage charge is imparted to the powder. The part to be finished is electrically grounded. When sprayed, the charged powder articles are firmly attracted to the grounded part's surface and held there until melted and fused into a smooth coating in the curing ovens. <br /><br />It's much more durable than liquid paint and it's an environmentally friendly process because there are no solvents to evaporate into the air or go down the drain. Different formulations (epoxy, urethane, polyester or a hybrid) are determined by the intended use of the item. For example, urethane and polyester offer the best exterior durability while epoxy is best for corrosion protection and chemical and solvent resistance. <br /><br />A range of literally thousands of color glosses, metallics and antique effects are available and local companies offers hundreds of "stock" colors all for same price. Consumers may also look through sample books and pick other colors to be ordered from the manufacturer at an additional cost (Powders must be mixed at the factory, you can't mix two together or stir in a pigment as with liquid paint.) <br /><br />It is also possible to have something matched perfectly by sending to the manufacturer for computer analysis. Computerized matching requires extra time and adds a considerably higher extra service charge, as well. (A builder might need metal doors to match anodized window frames perfectly). <br /><br />Because the surface of parts must be free of oil, dirt and rust prior to powder-coating, companies offer sandblasting, chemical and acid pre-treatments. The customary turn-around tiime is 7-10 days, and often job can be done sooner for an extra "rush" fee.<br /><br />Copyright 1999-2003, ServiceMagic, Inc. All Rights Reserved.<br /><br />More Products From The Internet's Largest Hardware Store<br /><br />c/6<br /><br />Hooty

 

[scubarobby]

Re: Anyone familiar with electrostatic painting?

I have seen similar painting done but it was usually fallowed by baking in an oven. I never understood the benifit but assumed it had to do with the baking more than the way the paint was applied. After it baked it would look very glossy.<br />I usually refer to it as powder coating. <br />just some thoughts I probably dont know any more than you.

 

[John Reynolds]

Re: Anyone familiar with electrostatic painting?

What I saw had nothing to do with dry powder, ovens, etc. It was just ordinary, wet spray paint. <br />But voltage will provide the attraction, the static effect, and current requirements will be minimal. 120 volts AC, rectified and filtered with a capacitor or capicitor-choke combination, will provide approx. 170 volts DC (120 multiplied by 1.414 to obtain the AC peak voltage). Since being a current as low as .035 amp could kill, and .010 is about the max one can take and let go, and .001 (one milliamp) is just a tingle, 170 volts divided by .001 gives a required resistor of 170,000 ohms in-line with the 170 volt supply in order to make it safe. I'll try a 200,000-ohm resistor or a 220,000 ohm resistor which are standard values, and will bring the current well below "tingle" value so that I won't be feeling crap if I touch something hot or short it out.

 

[ob]

Re: Anyone familiar with electrostatic painting?

Huh?

 

[John Reynolds]

Re: Anyone familiar with electrostatic painting?

I'm sorry about the technical stuff, but I was describing an easy way that I'm going to try to rig up something with a lot higher voltage that 12 volts to try to "electrostatically" paint my boat motor with spray paint. I figure that the higher the voltage, the better. I saw it done with liquid spray paint, and I remember talking to the painter about it.

 

[Hooty]

Re: Anyone familiar with electrostatic painting?

Don' zap yourself, John. We wanna know how it works.<br /><br />c/6<br /><br />Hooty

 

[John Reynolds]

Re: Anyone familiar with electrostatic painting?

Hooty, all that typing I was doin' was explainin' how I am intendin' to not zap myself. I was kinda hoping for some input. Weeeell, If'n no one hears from me come Monday, well then I zapped myself.<br />Perhaps I'd better hurry up and send that money to Scouts paypal account while I still can, eh? ha ha

 

[tmlee]

Re: Anyone familiar with electrostatic painting?

Let me talk to a bud at work. He used to powder coat bumpers. One thing i just thought about. If it is used on plastics, how do they ground that to apply the powder?<br />just a thought and I will post what he says tomorrow. <br /><br />todd

 

[Boatist]

Re: Anyone familiar with electrostatic painting?

John<br />170 volts will draw paint from only about 1/16 of a inch. You need over 10,000 volts for one inch and about 250,000 for 10 inches.

 

[John Reynolds]

Re: Anyone familiar with electrostatic painting?

Boatist - <br />Thanks a lot for the info. maybe i'll look into something with more voltage.

 

[Paul Moir]

Re: Anyone familiar with electrostatic painting?

Yeah, a furnace igntion transformer (~10,000vac, 29ma, 120vac In) and a rectifier pulled from the back of an old largish colour TV to make DC (Post tube days). If 70's to mid 80, the rectifier will be hanging on the big fat red wire attached to the tube. Later than that and it will be buried inside the FBT (the other thing the big fat red wire is attached to). Alternatively, MCM electronics can sell you one . Shoot for +15kv or better. Colour TV one should be good for +40kv. They will not test right with a multimeter, btw.

 

[John Reynolds]

Re: Anyone familiar with electrostatic painting?

I received the following posts from a couple of different forums where I posted the same question:<br /><br />All the major car companies use it. it reduces waste and clean up. As I recall the paint goes from negitive to positive. We used a paint booth and it extened the time between filter cleaning by a factor of 30. I used a 24V charger, the amperage is almost nill. (A friend used a DC welder and the paint blew up - you can go overboard)<br /><br />You are right about it being regular paint. This process has been used commercially for at least 40 years(less costly and more environmentally friendly). I've seen it done on metal office furniture also(this guy connected the furniture together with electrical clip leads and also used some kind of low voltage source).<br />Factories usually had spray booths with a water wall to remove what little paint overspray occured. Works real good and leaves an even coat(even on hard to reach places). I have no first hand information, but this may have been the process used on the motors originally<br /><br />So it appears that the process will still work without high voltage.

 

[alcan]

Re: Anyone familiar with electrostatic painting?

Hi John<br />About all I know about this type painting is that they use it to paint referigerated display cases. They can repaint a meat counter at night and have it ready for business in the morning. You may find more info with appliance painters. I also think there are companies who will come and change the color of your home appliances,using this system.

 

[John Reynolds]

Re: Anyone familiar with electrostatic painting?

Appliances! Never thought about that

 

[denniz]

Re: Anyone familiar with electrostatic painting?

Ive sprayed electrostatic fuelcell in jet air plane wings. It attracts overspray and is good for its intended use. You DONT need it for outboards. All you need is a good spray can.

 

[scubarobby]

Re: Anyone familiar with electrostatic painting?

I have always liked a can of good old oil paint (rustoleum) and a brush but I am used to working on comercial ships. You can all laugh now.<br />robby

 

[LuckyFish]

Re: Anyone familiar with electrostatic painting?

John I painted houseboat pontoons for Kayot Corp back in the late 70's. We used electrostatic painting using a industrial grade Graco electrostatic gun, and a marine epoxy paint after which we baked the pontoon for 1/2 hr at 180 degrees. It is a very durable paint, and the system worked well. Unless you are sure of what you are doing I would advise against using a jerryrig system like you are describing, paint thinners and reducers burn very easily much like gasoline. Any spark from the charger or ground hook up could ignite it. Marine based paints and primers are a better way to go for your situation I believe. Just my 2 cents<br /><br />Good luck, and be careful, Lucky

 

[John Reynolds]

Re: Anyone familiar with electrostatic painting?

It's not exactly Jerryrig; I described sound electrical theory and principles. But now I think I'll try instead is a high-voltage DC power supply that I have, which is intended for supplying high voltage for vacuum tubes projects/experiments. It's already self-limiting in the amperage dept. at about 10ma but I'll add some resistance so as to keep the current down to a few microamps so there will be no sparking and no shock hazzard. I'll also be doing this outdoors! Just in case, ha ha. I reckon my can of paint could be a flame thrower, eh? <br />Well, there's been enough said about this subject. I'll post my results in the days to come.