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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Strength and life of a powder coated part
Q. Dear friends,
We wish to know that how we can know with in 24 hours about the strength , approximate life of a already powder coated part (Zamak 3). Is salt spray test take much time for testing ? I am confident that your guidance will help me lot.
Thanks,
Asheesh Jindal- Delhi, India
A. Asheesh,
A reverse impact test with a good duct tape pull will provide quick information. The coating will be on the high side. Press firmly on the duct tape and wait a couple of minutes for temperature stabilization.
If powder coated area has poor adhesion, it may indicate a pretreatment process problem. It may also indicate a cure problem.
Herb Ashley- Smartt, Tennessee, (USA)
Q. Dear Mr. Herb Ashley,
We wish to know that how we can know with in 24 hours about the strength, approximate life of a already powder coated part (Zamak 3). Does salt spray test take much time for testing ?
One of our competitors says that his product has passed 4200 hours salt spray test. For it should we have to test a product for 175 days or is thereany method you can guide from which we can know the life in proportional system.
If pass ONE HOUR in this acid, then it is equal to 100 HOURS of salt spray test?
Asheesh Jindal [returning]- India
A. Asheesh,
The previous answer and a solvent rub test to ensure that powder is cured will indicate whether powder coating will withstand the salt spray test. Your powder supplier and technical data sheet information should be utilized for type of solvent to use for solvent rub test.
Herb Ashley- Smartt, Tennessee (USA)
A. I am not quite sure if you are relating strength with powder life of the paint. Understand that a salt fog test is a quick test of powder longevity. Even if it takes a month to achieve 1000 hrs, it is much quicker than testing in the sun for a comparison. Also, too many companies rely on salt fog testing. Remember that salt fog testing is SALT. Does your paint actually have to perform within this type of environment? MEK / methyl ethyl ketone rubs and crosshatch testing will not give you longevity estimates of any kind, but rather only definitive results of proper cure and or pretreatment results. I can only offer one test that may help. It is called AMA boil test. It is normally used for ornamental aluminum but seems to have a relationship for metal coated parts as well. The test is: Bring to boil De-ionized or Reverse Osmosis water. Once boiling, immerse your Q-panel, with a proper cross-hatch into the boiling water for 20 minutes. Then take the panel out and let it cool until ambient. Take a quality tape such as 234 masking or fiber tape and do your standard tape test. There should not be any removal of the topcoat. This test has similar results as would a salt fog test for 1000 hrs or so.
 Bob Utech Benson, Minnesota |
 Ed. note: Bob is the author of: "High Performance powder Coating" on eBay or AbeBooks or Amazon [affil links] |
Q. What is the life of powdercoated parts in normal utility
Sunil Shirke- Indore, M.P., India
June 22, 2013
A. Hi Sunil. Sorry but that is impossible to answer. I have bought many powder coated items of patio furniture that lasted but a single season, and I have another powder coated patio set that has lasted 20 years. If you do proper pretreatment, electrocoating, and powder coating, there is no reason your items couldn't last 15 years.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 2013
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