Spray painting & respraying a car.
"Spraying a Car Low Tech High End Result "
My experience is limited, I build Ferrari Dino replicas from scratch and this includes spraying them to a very high standard without the expected equipment but it means a lot of sanding.
I use 2K solid colour paint, for the work I do and I don't use a clear lacquer because I don't have the kind of facilities that are not going to effectively eliminate dust. A bit of dust below 3 layers of lacquer will become a big issue if you have to sand down to where it is then re-apply each layer. whilst with solid colours it can be quickly removed and covered with a bit more paint.
I use a couple of gravity fed spray guns, they are both economy guns. I use a 1.5 nozzled Metabo (£40) and a Kestrel detail gun with a 1.0 nozzle (£25). I have a water trap/regulator (£25) on the compress which is set at 4-6 bar. Using this method because the finish is achieved with abrasives and polishing the gun could almost be replaced by a brush if you have the skill in application or the time to spend flatting, you get your result.
So finishes absolutely needing a clear coat such as metallic or Pearlescent, I send out to those who have the facilities it demands. The key to a good finish is getting the finished paint perfectly flat and applying enough paint to be able to sand enough of it off to achieve this without exposing what's underneath.
My cars are similar in surface area to a Ford Focus which most painters might use say 3 litres of 2K paint on but I use 5-6 litres because I sand more off because my application isn't as flat as they would achieve and the required finish is flatter than they would need.
So long as you can get the paint on the car and its thick enough you can achieve a show class finish but you need to know how to flat it and you need to be willing to spend a lot of time flatting it. So the flatter the better and there are products out there to help if your using a spray gun, such as "smoother" its an additive that reduces surface pitting caused by a variety of contaminants and reduces surface texture. If your using cans, then lots of thin layers. Anytime your layering the paint to build a thickness it needs to cure enough to hold the weight of the next layer without rolling down.
The ideal time to recoat is when the paint is tacky like the back of a stamp but not really wet but if its totally dry remove the shine with a fine scotch cloth and apply a dust like gripper coat before adding any more paint.
If I was painting a full car I'd put half of my paint on in a day, over a full day then leave it over night before dulling the surface then applying the rest the next day, 3 days wouldn't be unusual. So with my final colour in place and having left it to set for 3 days at 25c I start sanding. First I remove runs and bumps that are in the paint using 400 grit wet and dry fixed to a lollypop stick with double sided tape and I take my time. Once all those problems are gone I start the main part of the flatting.
I use sanding blocks covered in 10mm soft neoprene rubber to ensure the wet and dry paper moulds to the shape of the body. I start with 800 grit, working methodically so that I don't miss bits and sponge the area down with clean water. I repeat this until the paint is free of any visible texture which normally takes a full day. I then repeat the process with 1200 grit and fresh clean water.
The water needs to be clean because it will have abrasive grit in it from the rougher paper if not and the paper needs changing regularly otherwise its going to take longer than it needs to. You can use machines for this but you don't need them and its safer not to because the paint will be relatively soft and you can easily pick up a bit of something and scratch the finish without realising its happening. I then repeat this with 2000 grit and then 3000 grit and its all done wet. The flatting process normally takes 3-4 full days.
The finish should at this stage look like a milky haze if you look at it square on but shiny from any sort of angle. The final process is applying swirl remover which is a very fine abrasive paste (polish on polish off) and that will reveal a fabulous finish and it can be done with patients but very basic facilities.
Before applying the coloured paint you should use primer and sand it back meticulously using the lollypop stick and 400 then 600 or 800 grit and if you don't prime the whole area at the very least it needs to be dulled with a scotch pad. I've attached a pic so you can see what can be done with cheap equipment and elbow grease.
I apply polish by hand because all the defects have already been removed during the flatting process (also done by hand). You can use a DA but if your environment isn't pristine the risk of picking up a bit of grit is high and with the noise of the DA you wont hear or feel it but it will wreck a paint finish. The approach is low tech but we are thinking about guys trying to paint in less an ideal circumstances.
This article has been written & submitted by Tom Marr.
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