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Paint peel off in pre-painted sheet

Sir,

I came across paint peel off problem in pre-painted sheet.

The material in which this problem was noticed was inspected by me. During production all tests were conducted like cross hatch, impact test, MEK test, bend test, scratch resistance test. All tests were found confirming to the requirement.

After installation of the same at project site, guard film was removed. During removal of guard film, removal of paint was found coming out with guard film in localised area.

Please suggest any method to ensure that this will take care of any paint peel off.

Regards,

Shivajee Pathak
- Nagpur
2003

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Dear Mr. Shivaji,

The problem appears of surface preparation or bonding. Paint peel off problem in pre-painted sheet in spite of inspection and tests during production tests like cross hatch, impact test, MEK test, bend test, scratch resistance test SEMs typical in nature.

R J Chaudhari
- Mumbai, Maharastra, India
2003

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This can happen if water ingress has taken place in the coated coil/sheet bundle. The color coated steel has great resistance to flowing water but not stagnant water. Water ingress can take place due to capillary suction during storage or transport. Once water enters the coil or sheet, guard film cannot protect the steel. Though we can not visually see, the paint layer has several micro pores through which the moisture can penetrate the layer and contact the steel substrate causing white rust and finally result into paint peel off. The material must remain dry until it is installed at Project site.
However, the white rust related corrosion can also take place if the coils are not properly produced or packed at the steel mill.

Prabhakar.R
- Mumbai, Maharashtra, India
October 2, 2012