Table of content

This defect occurs when the coating process stops for a period of time, hence its name. During the pause several things happen that affect the integrity of the coil:

The over coated portion of the product has an overly thick and irregular coat, inconsistent with the rest of the product. There is risk of peeling in the area adjacent to the over-coated portion. This section of the coil usually presents a darker color and is easy to identify most of the times.

This defect makes the coil unsuitable for slitting, as the defect would be present in each slit coil. However this is a good coil to cut into sheets because it is possible to discard the defected part this way.

BEST USE: Cut to length

One side of the coil is shaped as a bell and therefore is called "bell end coil". Sometimes the defect is subtle and not possible to observe with the naked eye, but becomes apparent when slitting or cutting the coil.

The affected part is the edge of the coil and covers between 50 to100 mm from it. The wavy defect is larger in the first laps of the coils but loses severity in the inner laps, to become almost absent in the end.

This defect makes the coil less suitable for cutting into sheets, as each sheet would be wavy. Slitting is a better application, because the wavy portion may be discarded by scrapping the first slit of 50 – 100mm.

BEST USE: Slitting

There are some small creases present across some portions of the width of the coil, although seldom throughout the entire coil. These creases are similar to the wrinkles left on a piece of cardboard after it has been rolled into a coil.

The breaks occur mainly on soft or very soft steel qualities where the coil doesn’t unfold into a smooth sheet, just as it would happen to the cardboard. They are usually small and approximately 1 meter between each other. The defect is difficult to notice it from the outside of a coil but becomes apparent when the coil is cut into sheets.

The defect is not serious if the coil is to be slit or cut to small sheets/pieces, but for larger sheets the defect is more obvious. The visual flaw is even more noticeable if these sheets are to be painted afterwards.

BEST USE: Slitting

The coils with this defect have stripes or scratches along its length; usually 1-5 mm long scratches beside one another. Their depth is normally of approx 0.1 mm.

These marks are sometimes visible from the outside and affect in average half of the coil. The stripes are usually only a visual defect in the coating and do not affect the zinc protection.

This is a coil made out of two sheets of steel rather than one. The individual sheets may be welded together or interleaved and coiled together without welding. When there is clear information about the coils being welded or this is spotted during inspection we write “welded” in the column “remarks”.

It is not advisable to slit a welded coil due to the risk of breaking the slitting knifes when crossing the weld or joint point. Cut to length is a better use, although attention should be paid not to cut over the point where both coils meet.

BEST USE: Cut to length

These are small spots without zinc coating. They are about 1 to 5 mm in diameter and are clustered in small groups and not all along the length of the coil, most of which may be problem-free. It is often impossible to see the defect from outside of the coil.

These are small spots with a defective zinc coat. They are about 10 to 30 mm in diameter and are clustered in small groups and not all along the length of the coil, most of which may be problem-free. It is often impossible to see the defect from outside of the coil.

These are isolated zinc knobs usually located on the edge of the coil. The clumps are small in size and usually located no more than 5 – 10 mm from the edge. The protection of the zinc coat is not affected.

These are either bigger zinc clumps or a cluster of clumps. The surface may feel on some few places like sand paper as a consequence of the zinc burls. The defect does not compromise the zinc protection of the coils/sheets.

The zinc coat is loose or peeling off the coil. It is possible to see the base metal, which usually looks black. The defect may be localized to a portion of the product but it may also be pervasive. Norex does not guarantee the performance of the product.

Affected coils usually show spots of dark grey color instead of red/white rust. This problem arises as a consequence of air condensation, that is, when light water spots form on the coils as a consequence of important changes in temperature in the storage facility or during transport.

Normally it is not possible to see this defect from the outside of the coil. This is a visual defect and does not usually effect the coating protection.

This defect refers to the discoloration of the protective film that keeps the zinc from developing white rust easily. It occurs when the coil has been protected with too much chromate oil in some areas. The imperfect part fades to yellow and may be a bit sticky.

This is a cosmetic defect only and does not affect the protection of the coating. In some cases it is possible to see the flaw from the outside of the coil, although not always.

The coil lacks chromate or oil protection and is therefore at risk developing white rust even just with regular air humidity. The coils are not rusty when arriving or leaving Norex (if rust is present this is indicated in the column "remarks"). Dry/Not chromate coils are usually produced to be painted.

There is a ridge or fold going through the length of the coil. It may be located on the edge or in the center. It is best to slit this coil to be able to remove the folded portion. Cut to length is not recommended as the ridge will be evident in every sheet.

BEST USE: Slitting

This is not actually a defect, but refers to a coil that has not been skin-passed (that is, it has not been rolled a second time for extra shiny look and more accurate thickness).

The zinc coat is not completely smooth. This defect does not imply peeling, but simply a cosmetic problem, and is limited to a portion of the coil. Due to its coarseness it is not suitable for painting.

BEST USE: Any application where a perfect surface is not required, for instance wall profiles.

The coil looks like it is covered in flakes of zinc, but the base metal is not visible under the zinc flakes. We don’t have information about the origin of this defect or if the zinc layer will peel off.

Refers mainly to Cold Rolled products and means that the outer lap of the coil has been affected by slight rust due to high air humidity while the inner laps are unaffected.

This is a white, powdery deposit that forms on the surface of galvanized products. It affects the zinc coat but not the steel it protects, but it is a mainly cosmetic defect.

White rust occurs when two galvanized sheets are in contact with each other in a humid environment. For this reason white rust can easily form in the inner laps of a coil. The development of white rust will stop once the sheets are separated, but if not it will eventually develop into black rust (see Watermarks / Water stained / Black Rust).

Sometimes it is possible to remove white rust by brushing or other methods, but a dark stain will remain in its place, so the cosmetic problem will not be solved. A more permanent solution is to paint the material.

To avoid the formation of white rust the producer may apply protection such as chromate or oil.

In this way we describe a coil that has collapsed slightly under its own weight or the weight of other products stacked on top of it. Instead of looking perfectly round like other coils, it is oval.

This coil has collapsed completely under its own weight, under the weight of other products stocked on top of it, or has been purposely flattened by a mechanical process, such as some prepainted coils in category N4.

The outer or inner lap of a coil has been drawn out so that the coil looks like a cornet. Due to this defect the material can be damaged in the handling. It may also be difficult to mount the coil in a cutting machine if the defect is too pronounced.

A coil affected with this defect has one side slightly longer than the other, and therefore sheets cut from this coil will be wavy. Slitting this coil is usually a better use. Customers using the material for small details and that cut it by hand can usually handle this defect better than others.

The coil has been damaged during handling. Examples can be when the coil is impacted by the lift fork, or has been dropped, or two coils have scrapped each other, etc.

This is a coil that is not galvanized or painted in its entire length. It is the result of a problem during the galvanization or painting that results in the interruption of the same.

A coil is perforated by a supplier following specifications from its customer, so perforation is not necessarily a defect but rather a feature of the product. However its use may be limited for a user other than the original customer.