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Powder Coating Question Results



All,

I'd like to thank everyone that responded to my question about the transfer
efficiency for powder coating operations.  The information will be very
useful and all responses will be passed along to the business as written.
For the benefit of all list members, I have consolidated the responses, to
date, below.  (I hope I didn't offend anyone, or mis-interpret any
information, by re-organizing/paraphrasing.)  If there are any questions,
please feel free to e-mail me directly for clarification.


Articles of General Interest

Knoll in East Greenville PA expected around 90 percent TE, and to recycle
most of the overspray.  They had 2 booths to avoid down time with color
changes.  System is about 2 years old.  Coating office furniture components
made of medium density fiberboard.  Lew Newett and Jay Fegley were the
contacts there.  Knoll developed and implemented powder coating systems,
which give a finish equal to or better than spray paint. The new technology
is essentially VOC-free and demonstrates a 98 PERCENT TRANSFER efficiency. 
	
<http://www.dep.state.pa.us/dep/rachel_carson/profiles/awards/1994/knoll.htm
>

Moore Products Co.
<http://www.dep.state.pa.us/dep/rachel_carson/profiles/awards/1995/moore.htm
>

Gilmour Manufacturing Company
<http://www.dep.state.pa.us/gov-awards/winners/12.htm>


Websites of Note

http://www.iwrc.org/programs/STAR.cfm

www.p2pays.org

www.peakstoprairies.org


Comments/Contacts/Programs

Consider the shape of the items being coated and possibly electrostatic
charge distribution.  40% does sound like a lot.

Contact the IWRC (Iowa Waste Reduction Center...link given above).  Those
guys know they're stuff BIGTIME. Contact Brian Gedlinske:(319) 273-8905 or
E-mail him: gedlinske@uni.edu    Trust me, you won't be disappointed.

60% TE with a spray-to-waste powder coating operation is not unusual.  There
could be grounding problems, gun setup
problems, better nozzles, room for improved spray technique, better racking
possibilities, etc.  We do offer a 3-day Painting & Coating Process Training
course that might be of interest to someone from the company.  If you get me
a mailing address, I'll send you a brochure.  The training is essentially
free (we cover travel, lodging and meals also).  Otherwise, we can try to
make suggestions based on information you provide us.  Let me know if you'd
like any further assistance. (brian.gedlinske@uni.edu)

Acceptable transfer efficiency for powder coatings can vary 
dramatically with different system configurations, part profile, 
etc.  Another powder coater I visited this summer was also operating at 40%
transfer efficiency.  They were curious about "average" transfer
efficiencies with powder coating, but I wasn't able to track one down.  I'd
be interested to hear what you find out.  (Judy Dorsey, PE, The Brendle
Group, (970) 207-0058, www.brendlegroup.com)

A 60 - 70% transfer efficiency would be common for a "spray to waste" powder
coating operation.
If they are spraying into a reclaim booth and reusing the powder, the number
should approach 90 - 95% even with color changes.  The powder must be
cleaned out of the booth and re mixed with the virgin material between color
changes in order to achieve these 
efficiencies.
I supervised an intern a year ago who worked on a large powder coating line
at Wenger in MN - the summary of the project is found at:
<http://www.mntap.umn.edu/PAINT/wenger.htm>

The general consensus is that powder coating is very efficient (average 95%
transfer efficiency as compared to 35% for conventional organic coating
techniques).  However, difficulty of color change-outs has been consistently
shown as a drawback to powder coating.  Usually the drawback is the
timeframe for the change-outs - not powder loss issues.
I have not heard of transfer efficiencies as low as 60%.  Did they talk with
their equipment vendor to do some troubleshooting?  I would also recommend
talking with other equipment vendors, consultants, their powder supplier,
etc. until they find a solution for their efficiency and powder recycling
issues.  You can find a list of contacts at sites such as
http://www.powdercoat.com/
A good article about different factors that may affect color change is at
http://www.pfonline.com/articles/pfd0037.html
It is critical that the company rethinks their operation to see if they can
do larger batches of each color at a time.  Do they have a booth that was
not designed for many color changes (some are better than others)?
If you have problems finding a solution from the powder coating vendors and
other experts, try Raytheon TI Systems, Mike Leake, Texas, 972-997-2958.
One of their projects is summarized at
<http://www.jgpp.com/projects/projects_index.html>, under completed
projects, low VOC.
The National Defense Center for Environmental Excellence (operated by
Concurrent Technologies Corporation in Johnstown) has powder coating
equipment and is doing various research about powder coating.  Projects and
contacts are summarized at <http://www.ndcee.ctc.com/>


Suggestions for Use of Waste

One possibility is to sell the mixed colors to an appliance manufacturer.
Domestic washing machine drums often have a (gray) "speckled" appearance.
Clothes dryers may be another application.

Children's metal swing set or garden tools businesses may provide an outlet.

IF the business sells the speckled appearance as a "feature" (easily
identified = no two alike, etc.), consumers may not view the mixed colors as
a problem.

Use leftovers as a gray primer.

There is a company in Louisiana called Filta-Tec.  They're program for
recycling powder coating filters might save some money.

Art reuse depots or community groups might be interested in the off-spec
powder and/or painted equipment.

Certain powders are recyclable (even the multi-colored speckled ones) if
they are the made from suitable resins.  One national company recycling
powders is Surplus Powders in Grandville, Michigan.  See
<http://www.surpluscoatings.com/>