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Powder Coating is peeling off on Aluminum - Can the color Be the problem?

I have been told that a neon orange piece that is peeling is because of the neon orange and not the application. We manufacture powered parachutes near Houston Texas, (Very humid and ocean salt area) and are looking for a company that can powder coat with very bright colors- and so neon was suggested. However- the Orange seems to peel off like skin- after a nick, or after drilling a hole through the aluminum. Is there a product that would not peel after drilling through the powder coated aluminum, and or chromally, that would stand up to some nicks, and outdoor use- (A powered parachute is a flying cart attached to a parachute- also called an ultralight aircraft). These planes are recreational and put on display- so a professional finish is a necessity.

Mary McAlpin
- Wharton, Texas
2005

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First of two simultaneous responses

Ask your coater about 3 things, the pretreatment, paint formulation and cure. The aluminum should be going through a conversion coating process, if they are processing it in a standard mixed metal phosphate bath, you aren't getting a good enough pretreatment for the conditions that these ultra-lights are living in. Tell the coater you want the aluminum conversion coated from now on and he should be able to have it done for you, it will increase the price of the paint job.
The paint should be a TGIC polyester/polyurethane (best for outdoor use) and the least probable culprit would be the cure, but you can ask what kind of results he is getting from his daily QC checks, also known as "MEK rub" test. Any credible painter will give you all of this info and help solve your problems without a squeal.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
2005

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Second of two simultaneous responses 2005

Dear Mary,

You do not say what type of powder is being applied.
From your description it sounds like a thermoplastic powder (Nylon or similar)and not thermosetting (polyester).
Thermoplastic without a primer will strip off if cut.

Polyester powder with the correct pre-treatment will bond to the aluminium and result in a minimum of 10-20 years service. Go along to your local shopping mall and see the shop fronts made from aluminium - all those are polyester powder coated.

So, check on the powder used thermo or plastic.
Check on pretreatment (both types).
It is definitely not your powder.
Note:
Neon powder will last along time (the coating)but will fade in colour much faster than normal pigmented powders.

Terry Hickling
Birmingham, United Kingdom

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2005

Dear inquirer,

You have clarified whether or not you are applying any type of pre-treatment before powder coating?
However color some remain problem but that can encounter.

Navin Maheshwari
- New Delhi, India

I agree with the two previous answers in most respects. The problem you are encountering has likely a root cause in the pretreatment of the aluminum. You might also have used the wrong powder. I would endorse the architectural grade PVDF powders and find an applicator that would warrant the application. The neon colors will never last as long as standard or even bright colors. The pigments are striking but never can stand the UV for very long. Get a great pretreatment and even a standard polyester will show durability if not sustained gloss and color.

Buddy Miller
- Claxton, Georgia, USA
2005

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2005

Mary: You are presenting two issues here. 1. Poor adhesion and 2. Long-term appearance.

It might be a good idea to go to the Powder Coating Institute's web site, and order the booklet about testing powder coating. Then find out what kind of powder your vendor is using. Do the cure tests yourself on each batch. They are very simple to perform.

Powder coating on Aluminum products are generally easy to cure because the aluminum conducts the heat so well, so undercure shouldn't be a problem. I say shouldn't be, but that doesn't mean that it is not a possibility. Grill your supplier on this point and test for cure periodically.

I agree that neon colors are not the best for outdoor exposure. You might contact a powder manufacturer yourself and explore that aspect. You can also get a list of powder manufacturers from the Powder Coating Institute. I believe you have a local manufacturer in the area.

If you still can't get acceptable parts, and are convinced that a neon powder coating will meet your long-term requirements - try a different powder applicator.

Daryl Spindler, CEF
decorative nickel-chrome plating - Greenbrier, Tennessee

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Mary
You live in Wharton, Texas the coater you have selected is most likely an oil-field coater. Meaning the majority of the business they service is epoxy based and the pretreatment they are doing is not correct. Not to say they are bad they just don't specialize in that aspect. Look at companies they do high end work, show Harley's and custom cars. But they are not cheap! Hope that helps

Roc Taylor
- Houston, Texas U.S.A
March 8, 2008

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June 16, 2010

To check if the Neon Orange Colour is causing the problem,
You may try with Ordinary pigment(non neon) based powder
coating.

Hari Gupta
- New Delhi, INDIA