Re: Powdercoating: Is it worth the cost over paint?
[Re: 1970RT]
#555528
12/16/09 09:24 PM
12/16/09 09:24 PM
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Joined: Jan 2005
Posts: 3,699 Newport, Mi
Evil Spirit
master
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master
Joined: Jan 2005
Posts: 3,699
Newport, Mi
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Applied CORRECTLY, powder coat is extremely durable. Unfortunately, a lot of it gets a bad reputation because of the people trying to do it at home in their Easy Bake oven. Just like with paint, proper prep is critical. Every thing that I have sent for coating I dressed the sharp edges of brackets, chamfered bolt holes, and if possible SAND blasted (not bead blasted - too smooth) for good adhesion. (which is also needed for a proper coat of paint!) I have parts that are over 15 yrs old and with a quick wipe down look new. I also had the bottom of the box let loose on a freshly coated batch of pulleys, bkts, etc. hit the concrete floor - and NOT ONE CHIP. It's just like with paint - there are HVLP jobs and then there are rattle can jobs.
Free advice and worth every penny... Factory trained Slinky rewinder.........
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Re: Powdercoating: Is it worth the cost over paint?
[Re: Chucklehead]
#555531
12/17/09 01:30 AM
12/17/09 01:30 AM
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Joined: Jan 2005
Posts: 3,699 Newport, Mi
Evil Spirit
master
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master
Joined: Jan 2005
Posts: 3,699
Newport, Mi
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Quote:
Quote:
Applied CORRECTLY, powder coat is extremely durable. Unfortunately, a lot of it gets a bad reputation because of the people trying to do it at home in their Easy Bake oven. Just like with paint, proper prep is critical. Every thing that I have sent for coating I dressed the sharp edges of brackets, chamfered bolt holes, and if possible SAND blasted (not bead blasted - too smooth) for good adhesion. (which is also needed for a proper coat of paint!) I have parts that are over 15 yrs old and with a quick wipe down look new. I also had the bottom of the box let loose on a freshly coated batch of pulleys, bkts, etc. hit the concrete floor - and NOT ONE CHIP. It's just like with paint - there are HVLP jobs and then there are rattle can jobs.
It can be prep and applied correctly at home. I have done it and it is like paint, if the prep work is not right the results are poor quality. The powder cures by heat, it does not care if it is an old oven in your garage or infrared heater or some high $$$ commercial oven. I have used both infrared (for large parts) and an oven with great results at home. The finishes hold up fine. Prep work is the key.
Exactly - proper prep is a must. I didn't mean that it CAN'T be done correctly at home - it's just that a lot of the ovens used aren't properly pre-heated, or can't recover fast enough to keep the temp hot enough. So then the part doesn't get enough "total heat" and isn't fully cured. It takes a separate thermometer; not the oven control; to monitor the temp to help make sure the oven stays hot enough, long enough, for the cycle.
On a related note - if a local pizza shop owner knew what his pizza oven was being used for after hours...
Free advice and worth every penny... Factory trained Slinky rewinder.........
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Re: Powdercoating: Is it worth the cost over paint?
[Re: DCI]
#555533
12/18/09 06:00 PM
12/18/09 06:00 PM
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Joined: Oct 2005
Posts: 8,882 Ontario, Canada
Stanton
Don't question me!
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Don't question me!
Joined: Oct 2005
Posts: 8,882
Ontario, Canada
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Quote:
I can restore any powder just like you can any paint
Talk is cheap! So much for the damage, let's see the repairs !!!
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Re: Powdercoating: Is it worth the cost over paint?
[Re: 1970RT]
#555538
12/19/09 05:31 PM
12/19/09 05:31 PM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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I think the one comment made and overlooked is about coating failure on the hard/sharp edge of 1/8" items. Almost all coatings will fail under those conditions. Paint, plating does not build on a sharp corner well. Deburring/fine grinding the edges helps a lot. Sandblasting helps a little bit. Once a base metal is open to moisture, every coating will begin to fail except maybe galvanizing. I like the deburring, then plating, then powder coating plan, but a 2 part urethane with a good primer is pretty durable.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Powdercoating: Is it worth the cost over paint?
[Re: jcc]
#555539
12/19/09 06:17 PM
12/19/09 06:17 PM
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Joined: Jan 2007
Posts: 2,212 Minnesota
peabodyracing
top fuel
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top fuel
Joined: Jan 2007
Posts: 2,212
Minnesota
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Lots of good discussion here, but there are 3 or 4 basic issues that need to be understood. The edge failure mentioned early in the posting is typically due to one of two reasons: if the parts were stamped, the sharp edge remains and unless it's been blasted or otherwise leveled out, will only maintain a very light coating of powder. When the powder gets beyond the 'gel' state curing the cure cycle it starts to flow in order to create the desired finish and gloss. Flow agents are varied depending on how smooth/shiney the final product is designed to be. When the powder flows, it tends to leave the sharp edge and because you're left with such a thin coating, many times no coating there, you get an early rust failure.
The second reason is due to what's calle laser edge. If the laser shielding gas used to cut out parts is set up 'on the cheap' a carbon build up is left along the cut surface. The powder sticks to this laser edge just fine, but any impact causes the laser edge to break free from the parent metal. The result looks like a paint failure, but it's not.
Prep is vital. A good shop with use a multi stage pretreatment system even after sand blasting. The addition of an iron phosphate conversion coating adds to rust resistance and helps paint adhesion. They used to use zinc phosphate which worked great but the EPA didn't like the heavy metals. Some locales have outlawed iron phosphates too because of sewage treatment plant concerns.
Chemical reistance can be greatly improved by using an epoxy powder coating. Other chemistries are optimized for UV resistance, ease of application, improved edge coverage, etc. Like everything in life, there are tradeoffs.
The cure cycle is very important. As mentioned elsewhere in this post the ramp up time and dwell time is important to create the desired end result. It also helps to have some air movement in the cure oven to remove any organics given off during the cure cycle.
You can touch up scratches and other damage in finished powder, but it isn't as straightforward as liquid on liquid because the touch up paint won't soak in to the powder. You need to rough up the surface some, usually with a scotbrite pad and may want to try using an adhesion promoter as well. The tough part is blending in the edges of the sprayed area.
We have a 50,000 sq foot powder coating facility but also cater to walk in business. Spend a fair amount of time with customers to make sure they know what their options and trade offs are. Even with that there's always one who apparently lost their common sense; like the Harley guy for whom we painted all his engine covers in a gray wrinkle and came back mad because they discolored when he sprayed oven cleaner on a hot engine.
Lead, follow or get the hell out of the way
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