Finishing Metals

Polythene is the most common thermoplastic powder which is used for this process. Air is blown through the powder to make it behave like a liquid. Metal pre-heated to 180 degrees is dipped in the fluidised powder and returned to the oven where it melts to form a smooth finish. Commercially used for products such as dishwasher racks, it is often used on school projects for coat hooks and tool handles.

Powder coating is an industrial finish which is more sophisticated version of dip coating. The powder is sprayed onto the productswhich flow through an oven. Modern powder coating provides a paint like finish and is available in all colours as well as transluecent,it is extremely durable.

Anodising is a process used on aluminium to provide a durable corrosion resistant finish - (this feature is important for a pedalo). It involves electrolysis and uses acidsand electric currents which are hazardous in school workshops. Colour can be addedto tint the aluminium. Most common finishing process used on aluminium.

Plating is another process which used electrolysis. There are many forms although chromium plating is the most widely recognised. The thin layer of metal on the surface providesa durable finish on metals which are prone to corrosion.

Galvanising involves dipping metal (usually mild steel) into a bath of molten zinc. The zinc provides a high corrosion resistant finish although not the most attractive.

Many products are self finished. This is true for instance of injection moulded products or in our case the hand lay up process the gel coat which is added to the highly polished mould ensures that the same surface is transferred to the product (pedalo). Basically self finishing means that once the product has been made there is no need to continue with any other processes because it is already shiny and smooth!