Application

Metal Cladding Coating

Coating specification for steel and aluminium cladding — substrate identification is the starting point.

What Is It?

Metal cladding coating requires the coating system to be matched to the specific metal substrate — and not all metal cladding is the same. Pre-coated steel (factory-applied plastisol or PVF2), galvanised steel, mill-finished aluminium, anodised aluminium, and Alucobond-type composite panels each have different surface chemistry, expansion characteristics, and adhesion requirements. Applying the wrong primer system to an aluminium substrate, for example, will result in adhesion failure regardless of how well the surface was prepared. Substrate identification is therefore the first task in any metal cladding refurbishment — not an afterthought.

The Process

Step 1 — Substrate identification: Visual inspection and, where necessary, material sampling to confirm substrate type. Step 2 — Condition assessment: Check for surface corrosion, cut edge corrosion, delamination of the existing coating, fixing integrity, and the presence of any previous refurbishment layers. Step 3 — Preparation: Pre-coated steel is pressure washed and mechanically abraded to key the surface. Cut edges are treated with ProFix rust converter and sealer before any top coat. Aluminium substrates receive chemical etching primer to ensure adhesion. Step 4 — System application: Compatible primer (where required) followed by the specified top coat system. Film thickness is measured and documented.

When Is It Suitable?

Appropriate for steel or aluminium cladding where the metal substrate remains structurally sound and free from perforation. The coating system must be selected for compatibility with the specific substrate — generic coating products are not appropriate. All systems used by Forti Nova approved applicators are specified for the identified substrate type.

When Is It Not Suitable?

Where metal substrates have thinned from corrosion, been mechanically damaged, or where dissimilar metal contact is causing ongoing galvanic corrosion, coating treatment alone will not resolve the structural issue. Galvanic corrosion between aluminium and steel components, for example, requires physical isolation of the dissimilar metals before any coating programme will succeed.

What Affects Cost?

Substrate type significantly affects cost through the preparation and primer requirements. Aluminium substrates require chemical primer systems that are more expensive than standard wash primers. Cut edge corrosion treatment (ProFix) on steel adds cost proportional to the linear metreage of affected edges. Fixing condition assessment and replacement, where corroded fixings are present, is a separate cost item that affects overall project economics.

What Affects Lifespan?

Metal coating performance over time is most strongly influenced by whether the primer system was compatible with the substrate, and whether cut edges on steel were properly treated. Both factors are invisible in the finished job but determine whether the system lasts 10-15 years or fails within 3-5.

Systems That May Be Considered

System selection is always confirmed through site assessment. The following systems may be relevant depending on substrate condition, project scope and specification requirements.

TopSpray 35 May be considered for the main sheet over-coat where the substrate has been prepared and a primer system is specified for steel. Suitable over synthetic systems including polyurea and polyurethane. Assessment required to confirm substrate compatibility. A Prokol Protective Coatings system.

ProFix Applied to cut edges before any primary top coat system — rust conversion, inhibitive primer and flexible edge seal.

Liquid Rubber SprayGrade