Metal finishing Q&As since 1989

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Are all Powder Coating processes viewed as Environmentally Friendly

I have a customer that is requesting we finish his aluminum extrusion in an environmentally friendly manner. It used to be done via a 10 micron clear anodizing. We obviously hear about the problem of VOCs with wet paint, and we hear often that Powder Coating is the way of the future. Many North American Powder Coaters claim their powders are 'environmentally friendly'. My question is simple, is it by virtue of the process that it is environmentally friendly, OR is it only specific grades of powder that really only qualify.

The reason I ask is because the part is finished in China, and I want to make sure that just specifying 'powder coating', will be sufficient for us to deem the part environmentally friendly.

I would appreciate a technical answer to this, so that I can back up my position with the customer.

Thanks,

Stephen Lawson
Supplier of aluminum extruded products. - Vancouver, BC, Canada
2007

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2007

When people say that powder coating is environmentally friendly, Stephen, all they really mean is simply that the coating is applied by melting rather than by the evaporation of smog producing VOCs. In that context, yes, all powder coating would be "environmentally friendly".

But I don't think powder coating is more environmentally friendly than anodizing and I'd like to know the basis for that feeling.

Thanks to Bill Vins, letter 6078, we offer the following quote from Lord Kelvin:

When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind.

A "meager and unsatisfactory" case could probably be made that anodizing is more environmentally friendly than powder coating of aluminum based on its freedom from chrome bearing pretreatment.

Unfortunately, while wanting to be environmentally friendly is certainly a good thing, the concept of saying one finish is more environmentally friendly than another is ridiculous 90 percent of the time. And the truth is, having it finished in China is probably the single most environmentally-hostile finishing decision people can make.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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First of two simultaneous responses --

Ted, huh? :-) Stephen, this work will be environmentally friendly to Canada because the work is being done in China. :-)

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
2007

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Second of two simultaneous responses -- 2007

Thanks Ted,

I agree with your comments, and essence that it's not just the process that makes it environmentally friendly.

We often see 'environmentally friendly' products from overseas being shipped half way around the world for consumption.....

However, our company is incrementally moving towards more eco-friendly solutions....be it from the transportation, packaging and indeed surface treatment of the products we sell. So if indeed Powder Coating is a step in the right direction, over clear anodizing, then that is a step we are considering. If however, it is environmentally worse, we don't want to go near it!

Can you give me your general opinion on that?

Thanks again,

Stephen

Stephen Lawson
- Vancouver, BC, Canada

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Sheldon, even ignoring the environmental consequences of transportation like Chinese freighters hitting bridges and spilling 40,000 gallons of oil into San Francisco Bay, or burning that 40,000 gallons of fuel in the transoceanic voyage, having things manufactured in areas where environmental controls are poor is environmentally hostile. When toxic chemicals are shipped to us from China for babies to suck on, pets to eat, or to be served as seafood, it is not a stretch to say that insufficient attention is paid to environmental consequences in China. There are hundreds of podcasts, YouTube videos, and feature articles in magazines visually documenting this environmental hostility.

Stephen, there are rare instances where it is probably reasonable to say that a finish is not environmentally friendly: cadmium plating for example. But most of the time the analysis would be far beyond our present computational skills. Still, clear anodized parts contain nothing but aluminum and aluminum oxide -- the principal component of the earth's crust; whereas powder coated aluminum parts usually require a chromium based pretreatment, and are shipped with this layer of chromium componds on them between the substrate and the coating. I personally do not think this layer of chromium compounds is a significant environmental issue, but there it is.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

I would like to add to Ted's comments. The powder industry is now realising that PC is not as environmentally friendly as we all once thought. There is a considerable amount of R & D going on around the world to find an answer to the vast mountains of waste (over-spray) powder being dumped in landfill sites. Some powder applicators try to solidify the waste powder in their ovens but are unable to keep up with the volumes of waste produced. It is a fact that 10 -15% of the powder purchased ends up as waste. I would also agree with Ted that the carbon foot print left due to importing long distances is not only environmentally unfriendly but in the long term will also be economically damaging to the USA and Europe.

Terry Hickling
Birmingham, United Kingdom
2007

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So Stephen, what is the presentation to your (potential) customer going to be?

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
2007

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Ted, I still get a sense that you feel powder coating is not a better solution. Let us assume the powder coating is done in the Canada. I still need to feel comfortable that this is a better solution than doing the Anodizing. in Canada. I understand that many shops use Non Chrome based pretreatments, and can dispose of any prewash very safely.....surely the anodizing acids are considerably more hazardous to the environment. Again, we want to start incremently improving the products we make, and this seems a logical step, but I am not hearing that from the comments in this thread. We cannot argue shipping distances, as that is a variable we have to assume constant for both finishes.

Stephen

Stephen Lawson
- Vancouver, BC, Canada
2007

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As mentioned, I don't think it's possible to make a strong case either way, Stephen. But we need to make a distinction between chemicals & other materials that are employed during the processing versus chemicals & materials that are shipped out into the environment on the part. As an example, chrome plating employs hazardous chemicals but the plated chrome is safe and it is possible to keep the hazardous chemicals wholly within the factory; in contrast, when one does cadmium plating he puts the hazardous material on the parts and ships the parts out with that material on them.

When one ships clear anodized parts, there is nothing on the parts but aluminum and aluminum oxide whereas powder coated parts will have chrome compounds on them. Chrome-free treatment is not as reliable, as witness the fact that military specifications do not accept it. Considering the cost and waste of corrosion it can hardly be called environmentally friendly to manufacture parts that are inadequately protected from corrosion.

The only chemical employed in anodizing but not in aluminum pretreatment is 10 percent sulfuric acid. So, yes, I think anodizing can be more environmentally than powder coating. But I still think you are requesting that I put a fine point on something that I've already said I can't put a fine point on :-)

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

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"Again, we want to start incrementally improving the products we make, and this seems a logical step, but I am not hearing that from the comments in this thread".

It seems to me that there is a lot of information in this thread containing information that you are looking for, it could be that the new test for the environmentally safe process could be in the way that the processing and distribution of the product is handled rather than the actual steps and chemicals used in the process(not discounting continual R&D). Chemicals are never going away, but the way the chemicals are handled and disposed of can improve. Environmental responsibility could be as easy as searching out the countries that have the most up-to-date enviro-concience and keeping them on the top of your list of suppliers. There are only so many countries and each one is blowing it's own horn on environmental issues because that it's the current rage. Surely your customer must understand that. Other than that nobody has any magic dust, we're all locked into using the most current technology.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
2007

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Gentlemen,

PPG industries have just published a white paper looking at the environmental, economical and performance advantages associated with the application of liquid and powder coatings on architectural aluminium. Quite specific, I know, but it gives a feel for the environmental advantages of powder coating over wet paint. It does not mention anodizing though. Makes an interesting read, have a look.

Hope this helps

Drew

http://corporateportal.ppg.com/NA/IdeaScapes/samples/download/

Drew Devlin
- North Lincolnshire
2007

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Thanks, Drew. I found the "Architectural Applications for Liquid and Powder Fluoropolymer Coatings: An Objective Review" very informative.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007