Repair

Yes. But before you do, clean the surface. This can be done using a mop or soft bristle brush with non-ionic detergent (such as kitchen detergent) and water. The surface should then be hosed down thoroughly with water and allowed to dry.

If the surface is new, it may contain some residual lubricants from the roll forming process. These should also be removed using the procedure outlined above. If possible, new surfaces can be sanded lightly to enhance paint adhesion. This is not required on older, weathered COLORBOND® steel.

Once the surface is clean, you can directly overpaint it using two coats (preferably) of a good quality water-based exterior acrylic. Please follow the manufacturer's instructions. If the steel is being used to catch drinking water, also check with the manufacturer that the paint is suitable for this purpose.

It's important to note that overpainting COLORBOND® steel will void any warranties issued by BlueScope Steel. Should, for any reason, overpainting be undertaken on behalf of and under instruction from BlueScope Steel, then a future warranty (if any) position will be negotiated between the customer and BlueScope Steel.

This information is intended as a guide only. For more information, Download Technical Bulletin TB 2 - Overpainting and Restoration of COLORBOND® prepainted steel sheet (224 KB).

BlueScope Steel does not recommend the use of touch up paints on COLORBOND® steel. The manufacturing process that gives COLORBOND® steel its colour and gloss retention properties means that the surface weathers differently to air-drying paint. After weathering, the areas which have been touched up will look different and can leave a blotchy look.

For information on how to keep your COLORBOND® steel looking great, view our page Maintain COLORBOND® steel and ZINCALUME® steel. If you think you may have fungus growing on the surface, view our page Identify and Remove Fungus.

Please view our page:  Remove Graffiti From COLORBOND® steel

Our recommendation is not to touch up. Minor scratching will not affect the life of the sheet and is rarely obvious to a casual observer. Should damage be substantial, replace the sheet. We particularly recommend against the use of spray cans, as these can result in overspraying of surrounding areas. The problem might not be immediately obvious, but since overspray paint weathers at a different rate to the oven dried paint on COLORBOND® steel you'll eventually be left with an unsightly blemish on the sheet.

The appearance of COLORBOND® steel affected by weathering can often be restored by re-painting. Please contact a roof restoration expert to assess the suitability of the roof for re-painting. If the roof is in a suitable state for re-painting please refer to the BlueScope Steel guidelines for overpainting, found in Technical Bulletin 2.

Download Technical Bulletin TB 2 - Overpainting and Restoration of COLORBOND® prepainted steel sheet (224 kb)

BlueScope Steel recommend 'cold cutting' coated steel products. If this recommendation is followed, these products will 'self heal', that is, the zinc in the surrounding coating will protect the newly exposed edge. How does this happen? In the presence of moisture, a reaction occurs between the zinc and the steel which results in galvanic protection of the exposed steel, thereby inhibiting corrosion. The degree of protection depends on the thickness of the coating (the amount of zinc), and this is taken into account when Building Standards are formulated.

This is usually a result of the use of touch up paint on the sheeting. The manufacturing process which gives COLORBOND® steel its colour and gloss retention properties means its surface weathers differently to air-drying paint. After weathering, areas that have been touched up will look different and may result in a blotchy appearance.

You're probably looking at swarf stains. Swarf is the term given to the steel debris arising from cutting or piercing operations, and mostly comprises of fine steel particles mixed with abrasive, however, in this context swarf may also be taken to include any other discarded steel objects such as rivet shanks, nails, screws and nuts, which may come in contact with coated products such as COLORBOND® prepainted steel and ZINCALUME® zinc/aluminium alloy-coated steel.

Swarf particles, if left on the surface, will corrode and cause rust stains which will detract from the finished appearance of a project. These stains are often mistaken for early deterioration of the roofing and walling itself.

The following link contains a guide for removing mild and severe staining from prepainted steel sheet and metallic coated steel sheet.
Download Technical Bulletin TB 5 - Swarf Staining of Steel Roofing and Walling Profiles (221 kb)