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Peeling after 180 Degree bend test

I did EN over Al. One of the criteria spelled out is no peeling after a 180 degree bend. Though it's not really peeled off, some blisters can be seen especially near the edge.
Any advise will be greatly appreciated.

Robert You
Job shop plater - China
2005

A 180 bend test is a very rigorous test for EN on aluminum.
You need a superior zincate and an excellent strike. Are you using the largest allowed mandrel for the test?

James Watts
- Navarre, Florida
2005

2005

While the coating will crack perpendicular to the bend, it should not flake, peel, blister, or otherwise come loose from the substrate.

Poor adhesion is almost always because of inadequate pretreatment. You do not say how you cleaned the coupons.

Ron Duncan [deceased]
- LaVergne, Tennessee
It is our sad duty to note Ron's passing on Dec. 15, 2006. A brief obituary opens Episode 13 of our Podcast.

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