Most modifications to a motorcycle can be measured in clinical, objective terms. Engine improvements make increased power, demonstrable on the dyno. A stopwatch can time the effect of suspension changes. New rearsets improve ground clearance by defined amount and braking components can be judged by measuring simple stopping distances. But there's one modification that can only be gauged subjectively – a new paint job. It takes some feat of engineering to make a change stand out from standard, but even the simplest of paintjobs can be enough to get you to stop and stare.
The process of spraying a motorcycle is one of those jobs that seems simple – grab a can of paint from the local DIY shop and do you best art impression by spraying it onto your fairings – but it's only after watching the experts do it properly that you start to understand all the work involved in that seemingly simple operation. We had the opportunity to see a motorcycle paint job being done.
Motorcycles come to the painter in one of two states; bog stock or in crashed pieces. A bike crash is often what prompts an motorcycle owner to do a paint job. Often one look at the cost of new parts needed to rebuild the motorcycle is enough to prompt a stylish but economically sensible approach. If plenty of panels have gone down to road, getting a motorcycle to its previous state costs pretty much what it could to do a whole new transformation. Of course, once a motorcycle comes in any repairs need to be done first, and our motorcycle painter use the strongest product for the problem. After any plastic welding and filling has been done, a high build primer then goes on that prepares the surface for the paint proper. If there's been a lot of work undertaken then a 'wet on wet' primer will go on that you use like a lacquer to show any imperfections at this early stage.
Even on a perfect motorcycle, all the stickers and graphics have to come off, otherwise these raised areas will stick out. Spot priming is used now, especially when painting a helmet, as the lacquer sinks back into the hole, highlighting any imperfect areas. Poor prep work only leads to compromised results further down the line.
With our motorcycle, we'd come to our motorcycle painter with a rough idea of what we wanted the motorcycle to look like, giving it the theme of the latest original factory paint scheme, but we wanted to bring it bang up to date with styling to match. IT was also important to make the motorcycle a celebration of the ten years of the model. We wanted lots of subtle touches and the motorcycle to draw you in ever deeper. Well, it's one thing saying that quite another thing achieving it, but our painter came up with some great concepts on his computer that we decided to run with.
So with this prep work done and the idea in place, and get dressed up in overalls and mask before heading into the spray booth to put on the base coat. This is normally the most prominent color of the paint scheme, although if it's black subsequent colors may need an extra coat to cover this. The base coat goes on in light coats. A 'drop coat' is used first. This gives good grip for other coats to be applied on to and is done by holding the gun further away from the surface. Next come two 'wet coats', which are sprayed much closer than the drop coat, followed by a final drop coat that avoids a patchy finish. Depending on the number of parts to be painted, this can take anything up to 20 minutes a coat – our painter make a point of painting the backs of the fairings, too. Being presented with a fairing with loads of over-spray on the B-side isn't what you'd really call professional – more like a back alley badge job. All told, on our motorcycle many plastic parts about a liter of black paint was used.
Once the base coat is on, this is then let to dry in the spray booth that also acts as an oven. It's standard plus 30-degree Celsius in the spray booth.
Once the paint is dry, the next coat can be marked up. This is done by hand according to the design and uses different width tape to get the desired line. Masking tape then goes over this before the rest of the panel is wrapped up in paper to avoid any contamination.
Our painter can create any color they need with a computer driven mix machine in the mixing room. This tells our painter how much paint to mix in proportion to another. There are so many variables here, so even if a stock color is needed the 'chip' given for each motorcycle could not quite be right, so the human eye with a few lights and outside sunlight are often a better judge. In the past our painter tells us that in the past he painted many CBR150R's and they had slightly different colors, so not even the manufacturers get it consistently right. Solvent or water based paints can be used, although they look different in daylight – the only true judge of paintwork. Most manufacturers now use water based paints to conform to environmental regulations, so any repair would have to use the same.
The thick paint is then mixed with thinners to get it to the right consistency in the spray gun. The proportions are normally two parts thinner to one part paint, but if you are doing a fade on the motorcycle you want to use an even thinner mix.
With the lines marked up, a solvent-based degreaser is used to wipe away any marks or glue from the tape. Then another wipe and a blast from the airline gets any fluff off from the first wiping, to leave a perfect surface, ready for painting.
It's tricky to get the edges right. Paint obviously forms a layer, and too big a layer can look wrong. So the edges are painted first to try and prevent this build up, and the trick is to put as little on as you can get away with. It's likely that this is the stage where more detail is added to the scheme, often using a metallic paint, so care is taken using a final drop coat to avoid the metallic sinking and looking patchy when dry.
Most professional painters are willing to work to various budgets and can accommodate almost everybody.