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  1. #1
    Join Date
    Aug 2003
    Location
    Wodonga
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    59
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    96

    Default Powdercoating advise

    Hi guys and gals,

    Looking for a bit of help please. I have just welded up an outdoor table that I wanted to get powdercoated.

    There are some areas that need filling and sanding to cover up some horrible welds and I need a product to fill with that is compatible with powdercoating.

    All the local powdercoating companies just shrug their shoulders and say don't know.

    Does anyone know of a product that will work?:confused: :confused: :confused:

  2. #2
    Join Date
    Dec 2004
    Location
    Hell with fluro lighting
    Age
    55
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    491

    Default

    LEAD ?? The old timers used it as car body filler. it is metal, should work...
    I may not have gone where I intended to go, but I think I have ended up where I needed to be.

    My Other Toys

  3. #3
    Join Date
    Dec 2005
    Location
    Ohio
    Posts
    3

    Default powder coat filler

    Im sorta speaking out of my league here, but i will get a definitive answer for you by tommorow, it shouldnt matter with the powdercoating unless its a vertical surface, the powdercoat will lay down on it and stick when heated, the metal polarization to help it stick is mostly for verticle surfaces was my understanding of it, we used to powdercoat things at work and it was farrrr less superior to traditional two part polyurethane paints, so we went back to that, the sharp corners we produced would not let the powder stick and they rusted quickly IE before the product shipped.

  4. #4
    Join Date
    Aug 2004
    Location
    Wide Bay Qld.
    Age
    81
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    1

    Default

    As powder coating will not build up a good thickness on sharp edges it is prone to rust in these areas so for outdoor use have it galvinised first and you will have no rust problems, smooth out the welds with an angle grinder/sander if you think its to rough.
    Cheers Arch.

  5. #5
    Join Date
    Aug 2005
    Location
    kiama
    Posts
    53

    Default

    lead is not going to work for powdercoating it melts at a lower temperature than the powder. Depending on the powder it may need 200 or more degree Celcius to melt it. Had a guy try to powder coat a petrol tank and the seams all came loose and the solder ran out. When we put a stick of lead in the oven it turned into a pool of lead.

    Weld and grind as much as you can to get a smooth surface if this is not good enough braze the bad spots and grind or file them smooth.

    The better the surface the better the finish.
    Powder puts on an even coat as it is done by electrically depositing the powder it won't put on more until the area has reached an even coat it always travels to the thinnest spot. If the surface is rough it puts just as much on the high spots as the low ones. smooth metal and you can get a mirror finish. (though gloss level of powder is not quite as good as paint.)

    If the metalwork is complicated powder is the answer, on a car wire wheel for instance you easily get a wonderful result, try to spray one and you can get bald spots in some areas and runs in others as you have to point the spray gun at every side of every surface and you end up painting ones close by which you have already done. Powder coating requires no real skill most of industrial work is done using robots which just spray the powder into the air as the object passes by. The powder wraps itself around the object, paint a piece of pipe by waving it over the front and it will wrap around and paint the back.

    It would have to be a pretty sharp edge for the powder not to cover it. If the applier preheats the metal before the powder is applied the powder will stick to the edges and any areas which have a deep hollow.

    If you remember magnets from school you will know opposite poles attract each other so the powder attaches itself. If the metal has a piece of metal close to it it will act as a repellant and form a field preventing the powder from attaching itself. If you heat the metal when you fire the powder at the area it sticks because its hot and doesn't get shoved off by the force field.

    If you have cast metal you need to preheat, when you put on the powder the cooling metal sucks the powder into the paws or holes in the metal and fills them if you do it cold the powder lays in the hole and when its heated the air underneath blows the powder out and it comes out full of pin holes.

  6. #6
    Join Date
    Aug 2003
    Location
    Wodonga
    Age
    59
    Posts
    96

    Default thanks all

    Thanks to everyone who took the time and effort to reply.

    At this point in time I have decided to paint, as all the local powdercoaters I have talked to, wont guarantee that anything I use will be OK.

    I know that if I paint it, I can always touch up in years to come, but if powdercoat fails, then I am left in the lurch.

    Thanks once again.

  7. #7
    Join Date
    Jan 2004
    Location
    St George area, Sydney
    Age
    65
    Posts
    22

    Default

    I'm displaying my ignorance here but isnt the powder applied electrostatically and hence the surface would need to be conductive

  8. #8
    Join Date
    Nov 2004
    Location
    Bungama SA
    Age
    52
    Posts
    960

    Default

    Quote Originally Posted by DW
    lead is not going to work for powdercoating it melts at a lower temperature than the powder. Depending on the powder it may need 200 or more degree Celcius to melt it. Had a guy try to powder coat a petrol tank and the seams all came loose and the solder ran out. When we put a stick of lead in the oven it turned into a pool of lead.
    Your oven must be hotter than 320°c because thats what lead needs to melt into a liquid form.
    Geoff you use your welding rods as the filler...
    ....................................................................

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