Powder coating reclaim

A. Your powder supplier may be able to provide the training that you imply is lacking.

1) There is no straight answer here as so many factors exist that contribute to or detract from transfer efficiency, but with densely racked parts, well balanced air flows, and proper grounding it is fair to expect around 60 to 70% usage without reclaiming overspray.
2) Mixed waste powders can be used on any number of items that have loose appearance requirements or low corrosion resistance needs. With some minor experimentation and creative marketing, you may find that most waste powder can be used.
3) Yes there are uses beyond coating for waste powders, but the great variation in mix can be a problem. Always sell any waste mix "as is".

A. ... but make sure they sell it, not give it away, nor pay a reduced disposal cost for re-use in lieu of landfilling. Consult an environmental attorney for specific guidance, but be aware that in the USA if this is judged a hazardous waste product, they may be responsible for it forever, no matter how much they pay for disposal.
Luck & Regards,


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

A. The solution that pros use in to not send it to waste. With proper containment and filters, it is mixed with virgin paint and reshot (automatically for really heavy paint users). Note that this makes color changes difficult as the filters have to be changed and the system cleaned extremely well if you do not want specks of the old color in the new color, or worse, two different formulations of paint.

A. Hi,
It is quite simple: start in the morning with a clean spray booth and at the end of the day's shift clean out the spray booth and filters, then weigh the resultant powder. Simple mathematics will give the approx. efficiency of your plant. Experience shows manual booths without recovery results in 50% of the applied powder ending up as waste. Automatic plants, dependent upon design, can achieve 85% efficiency if the recovered powder is circulated back into the system.

However, waste is not always the answer to overspend -- your quotation to a customer may be based upon applying 2.5 mls film weight of powder but in product, the actual figure maybe 3-4 mls a very big on-cost. Check film weights twice a day to maintain cost effective powder coating.

A. I might have to ask how & where you think you are & are not making money if you are not already taking into consideration what is going to be suggested to you by people answering this question. Mr. Hickling is right on as weighing what you are throwing away and maintaining a consistent coating thickness is pretty standard for calculating P&L for a powder coat line.

Maybe you should go to the Powder Coat Institute site and buy the book they have on setting up a powder line for profitability, it should tell you every thing you need to know to troubleshoot your cost analysis.

A. Another point of view is this: compare the good/bad products with powder lost and establish the optimum.

A. DEAR SIR,
I THINK MOST OF YOUR PROBLEM WILL BE SOLVED IF YOU BUY A POWDER OF BETTER QUALITY, I.E., WITH A LOWER SP. GR OF 1.3 - 1.4 AND HAVE A BETTER SPRAY BOOTH DESIGN SO THAT IT CAN RECOVER THE POWDER. YOU SHOULD GET MINIMUM OF 75 - 85% RECOVERY.
ALSO SEE IF YOU ARE WORKING ON PROCESSES IN PRETREATMENT WHICH ARE NOT REQ'D, LIKE DERUST FOR GALVANIZED OR CR SHEETS.

HOPE THIS WILL HELP YOU.
REGARDS

A. I had a company that would pick up our waste paint and apply it to steel grating that was going to be put underground and had no cosmetic value. That encompassed about 3 months out of the last 16 years as a powder coater. Cosmetics are the main reason that you can't re-use powder that is in the waste barrel due to the conditions that you have mentioned. Otherwise, it's typical to re-box the paint and melt it in the oven, then send it to the dump, or put it in a special container and have it removed.
I don't know of an available database that keeps the kind of records on waste powder that you are looking for, probably because it's not a hazardous material so there isn't any reason to keep track of it.

A. I just suddenly went by this post and I know in Canada there are companies collecting this kind of waste powder. They can even collect these waste overseas.

A. The powder can be reused again. Re-extrusion, if it is not too reactive, or even converted to texturized powder paint. It could be reclassified and used or blended with fresh powder and consumed. Not aware of any other use. Anuradha, you were doing some research on reuse of waste powder. Can you enlighten us more on this?

A. Why not sieve the powder, mix it with water, apply with an air-assisted spray gun, and bake as normal. Could be used as primer coat or on areas not seen. We sold our aqueous powders as final finishing coat. This was applied to areas where the Faraday cage effect was bad. Further along the track, powder was applied electrostatically (actually the same material but in powder form) and the system baked. It is not quite that simple but with some R & D, it works.

A. Hi Anuradha,
For information on the financial constraints faced, it would be proprietary information of powder coating manufacturers. However, many companies could give you such information if you approach them directly. To answer your question, there is much R&D going on here in India to recycle such wastes!

A. If I could make an observation, if powder waste could be reused on a large scale it would already be happening. It can't be re-extruded, and the logistics of re-blending with fresh powder certainly eliminate any cost savings.
All it costs a company is the trip to the dump, and that element should be easy enough to figure out.
The initial pricing of the application should cover the cost of the waste, so it is paint that the customer has already paid for.
The bigger issue is that nobody is going to pay much for regurgitated waste powder even if a secondary use was found for it. As mentioned, I had a person that was picking up my waste powder for a couple of months to sift and spray on steel grating that was going to be used underground and had no cosmetic value, but he wouldn't pay me for it.

!! Hi. Here in the USA, recycling of industrial waste is nearly impossible. To stop midnight dumpers who would then disappear, our regulators instituted "cradle to grave" responsibility for waste -- meaning that if it's judged hazardous the waste generator is held responsible for it forever, no matter who they paid for disposal or how much they paid. Further, "joint and several liability" means that even if you are just one of many sources of a batch of hazardous waste, you are still financially responsible for all of it.

Although powder is probably not considered a "hazardous" waste today, no one knows the future; plus, many powder coating shops also do other processes which do generate hazardous waste, and accidents or duplicity can happen; so people are leery of accepting waste powder; the generators seem to prefer paying to have it traceably landfilled than just taken off to who knows where, and then being forever responsible for a potential cleanup in the future.

In the early 1990's a large amount of public money was given in grants for the establishment of "Industrial Waste Exchanges" (we had a very big one here in the Northeast). But once the government money giveaway was over (plus the implied governmental wink if something went wrong), it's apparently impossible for anyone to keep an industrial waste exchange going (I can't find even a single one remaining in the whole country). As long as it costs little to send waste to the dump, and there is huge non-predictable risk in doing anything else with it, that will probably remain the prevailing practice. I don't have a good alternate answer :-(

Regards,

A. Here in India, powder coating is quite expensive to be thrown away and there are many ways we reuse this. One novel way I came across here in India is converting it into fancy articles like paper weights, by melting and pouring into molds and baking. Quite innovative! But I gather this would require addition of additives to make it more workable.
It could be also be converted to textured and soft feel powder coating. Another use during my search was US Patent 6,881,762.

A. Hey guy, the waste powder is very simple. All you need is to find the right person to reuse it. I am working in a powder coating line. The guy just come in twice a month to pick up the waste free for us. They reuse the waste.

A. Hi all,
I work for a company that currently is recycling around 100-200 tons of powder coating monthly and can do a lot more. We recycle it into various applications. Resin content, construction filler, protective coatings, and many other applications.

A. Powder recovery can be an effective means of re-using the overspray from "spray to waste" operations, but you need to balance the expected savings against the cost of the installation.
You could expect in excess of 90% of the powder to be fully used in a recovery system. A good system will have cyclones to recover the overspray, but cyclones are not 100% efficient, and a proportion of very fine powder will pass them to an after filter. Sieves to ensure that coarse matter does not get recovered will be included, and cycloned, sieved powder will report back to the powder supply container.
There's a limit to how many times powder can go round the circuit. It will break down becoming finer, and so eventually not get caught by the cyclones.

Reputable spray booth manufacturers can supply fully recycling booths.

? Hi,
The answer is yes but we need more info. For example, how many colours do you use?

A. I change colors with every piece I coat. The filter catches would not work too good for me.
I use a 1/8 thick 3' by 3' piece of aluminium plate under the piece I am coating and I have my ground cable hooked to it. 90 percent of my overspray gets sucked to that plate. Then I squeegee the powder off into a container. Only takes few seconds to change colors.

A. Proportionately you're throwing away the same amount of powder as before, and it's powder that the customer is paying for, so right now you should be status quo. There are several quality issues you will have to deal with if you decide to reclaim ... are you ready to tackle them as they surface? Hint: they will surface as defects, so until you fine tune the system and train personnel, expect a lot of rejects.
It could take more time and effort to deal with the problems than to continue with what you are doing unless you become truly dedicated to the cause, and as Mr. Crowley pointed out, add the cost of installation on top of it.

A. Hello friends,
While surfing, I was came across question and answers related to use and problem associated with powder coating waste. I am ready to share my ideas on it. Right now I am doing research on the said topic. Kindly share and exchange ideas with me. I will try to find solution, your queries are always welcome, I am sure that your queries and my difficulties would certainly solve the problem, which industries are now a days facing.
Can I get/expect e-mails from researchers or people who are doing research in the same field?
Thanks

Ed. note: Hi Pramod. Taking this public conversation private would disenfranchise all the other posters and readers, cutting them adrift unsatisfied :-(
Instead, please publicly share whatever you will or answer some of the open questions on this page -- we promise we have all the room in the world if you are "ready to share ideas". Thanks :-)

A. Try preheating the part before powder coat, this will greatly increase transfer efficiency, check grounding with a ohm meter, and regularly check kv output on powder guns.

A. Dear reader,
I am also wondering about the reuse of waste powder coating .
I think we can certainly do something for this.
First we can add resin in a mixture. Secondly we can use discharged powder on preheated product. Thirdly we can sell it to shoe polish maker. Apart from this if you have any ideas please share it in favor of the earth.
Regards

A. We had someone wanting it to use as a binder in making bricks of other wastes, but that company failed. It seemed to work while they were still operating.

Hi. If you were in the USA you might find yourself responsible for the environmental cleanup of that failed brick-making operation :-(
My limited understanding is that it's important to get a token payment for the product because that way it wasn't waste if that brick-maker ended up using or producing anything deemed hazardous.

Regards,

A. Well there are 2 main recovery systems for powder overspray.
The first is a cartridge filter type system where overspray is collected in the filters and discharged to a hopper by reverse pulsing the air flow to the filter cartridges.
In this system very little degradation of the powder occurs and the reclaim can be totally re-used. The system does however have significant other problems.
The second and most widely used system is the cyclone style recovery system.
This system degrades the captured overspray powder as it impinges on the cyclone walls and breaks down the particle size of the reclaimed powder.
With this system the commonly accepted rule of thumb is to use no more than one third of reclaim to two thirds of "virgin" powder.

Different Powder manufacturers employ very different formulations to achieve very similar if not identical finished results.
Mixing these different formulations is playing Russian roulette.

The major problem encountered when using too much re-claim is a drop in "transfer efficiency". Essentially the powder does not stick to the target. This is not normally described as an adhesion problem. Adhesion is normally described as the adherence of cured powder to the substrate.

Hope this helps,
Regards
Bill

A. Sir,
Could you please define your method of calculation of the 10 %:
Are you talking about 10% of the reclaimed material?
Are you talking about 10% of the "virgin" powder?
Are you talking about 10% of the reclaim-"virgin"powder mix?
It is easy to imagine such a high waste stream if re-claim is added in excessive volume to the powder supply.
Otherwise this % is excessive.
I do not know of any use for degraded powder fines from a cartridge filter post-cyclone recovery system.
Please help me to help you by defining that 10% more clearly.
Regards,
Bill

A. Hi Atul. That's been the subject of this thread for 20 years now, and several other threads on this site. In addition, you can probably read several papers on the subject if you put "recycle powder coating" into scholar.google.com. But I don't think anyone can give a quantitative answer to how much of a problem it is. Good luck.

Regards,

A. Good luck DC. It's very tough to make use of industrial waste products today.

Regards,