Feature: why paint when you can powder coat?
Powder coating offers durable and long-lasting protection for your automotive components
The idea of restoring a classic car or bike can seem exciting until you spot all the rusted metal components. The solution is to give these items an in-depth clean to remove the rust before painting them first with a primer and then a series of base coats. Or, you could save yourself the effort and have them powder coated by the professionals. This form of protection offers a smooth finish that is more hardwearing than any paint layer. We spoke to Lesley Christie, director at Castellocote in Cape Town, to find out what the process entails.
As with conventional painting, preparation is key for a good result and a lot of effort goes into cleaning the metal components beforehand. This includes dipping the items in a de-rust solution for an hour (if needed) before washing them with a highpressure cleaner using a hot-water solution. Then the component is either shot- or sand-blasted to remove any impurities, after which the threads and other areas not requiring coating are carefully masked.
As the product is a fine, dry powder, colours cannot be mixed, as with conventional paint. Therefore, you need to pick a colour beforehand. A powder-coating shop usually has a number of spray booths already set up with popular colours. If you need another hue, a small setup fee is charged to prepare a booth.
The component is supported in the booth with hooks or a jig to provide easy access for the spray gun. An electrostatic charge is added to the powder particles by the machine feeding the spray gun, which is then sprayed onto the component at low pressure. Skill is required to cover the part entirely. There is surprisingly little wastage because most of the powder tends to stick to the component. Any excess powder is extracted from the booth and recovered.
The covering thickness achieved on a room-temperature (cold) component is around 100-120 microns but this can be upped to 300 microns if the part is pre-heated before the powder application.
An oven warmed up to 220 degrees Celsius is needed to cure the powder layer. The particles melt to form a single layer covering the object. It takes about 30 to 45 minutes depending on the size of the items. Castellocote’s oven is the size of a 20-foot shipping container, allowing large objects to be baked.
The components are cooled naturally and are ready for use, with no drying times as with conventional painting.