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Cut edge corrosion treatments

Understanding Cut Edge Corrosion – CJ Paint Spraying UK

Previously the usage of corrugated steel and aluminium sheets was limited pretty much exclusively to the cladding of barns and sheds. However over the years this has changed and now this material, which is referred to as “crinkly tin” by architects, can be widely seen on the elevations and roofs of a whole host of commercial buildings.

A conservative estimate suggests that as much as 60% of all cladding currently in use suffers from cut edge corrosion. The problem is such that the majority of commercial owners are often blissfully unaware that their cladding has cut edge corrosion, whilst many do not know what it is.

What is cut edge corrosion?

Typically, when metal cladding is manufactured the sheets are coated in a plastic, such as Plastisol. The function of this coating is twofold, it protects the underlying metal from corrosion, whilst also improving its appearance. However when cladding is cut to the desired size for its application, the edge is not coated. A steel edge which is exposed to oxygen is prone to corrosion and subsequently the plastic coating can begin to peel back from this edges.

Cut edge corrosion can occur on any edge of metal, therefore it is often found on the edges of sheets where they overlap one another and can also occur in eaves. Areas which are particularly vulnerable to cut edge corrosion are the horizontal laps of sheeting. Whilst cut edge corrosion typically begins on the edges of metal sheeting, it can spread with increasing speed through capillary water action to consume the whole sheet.

Repairing cut edge corrosion not only protects cladding from both pollution and the elements, it also reduces the amount of coating which peels back. In addition, it will provide a tight seal on all horizontal laps, lap joints and the edges of cladding. To be truly effective we encourage that any cut edge corrosion restoration work is undertaken by trained professionals. In such instances, the repair work will not only protect the building structurally, but also improve how it looks.

How to repair cut edge corrosion:

  • Inspect the cladding in order to gauge the extent of any and all damage which has occurred. Also assess the amount of products which will be required for the repairing and re-coating of the cladding.
  • Thoroughly clean the surface, removing any moss, algae or grime from the roof’s surface. This can be easily achieved with a high pressure jet washer.
  • In cases where the problem is particularly severe, any flaking paint or rust will need to be removed. This can be done either mechanically or using a brush.
  • Then feather the edges of the original peeling and delaminated areas, so that when the new layer is applied there are no ridges.
  • Clean the cladding surface again, this time using a degreasing agent. If this is not done any remaining grease will prevent the new coating from sticking to the cladding’s surface.
  • Apply sealant to the panels in order to fill any large gaps which appear between overlapping cladding panels.
  • Finally, and most crucially, re-spray the cladding with an appropriate top coat, one which has been specifically manufactured for PVC coated metal cladding.

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“We have used CJ Paint Spraying a couple of times for on site spraying services along with repairs to our external cladding. All of the work they have completed for us has been spot on! It always looks brand new, and the teams are friendly and professional, we couldn't recommend enough.”

David Netherway 14th March 2018