When building a street rod there are a variety of milestones that make all the effort expended worthwhile. A big one for us was shooting primer on the world's longest running magazine project, the RamRodder.
Painting a car is a huge undertaking. Maybe if our budget could have handled it we would have dumped the thing off at the door of the nearest body shop and told them to call when it was done. However, since so much of what makes a good paintjob is the labor prior to shooting the final coats of color we figured that we could do a good deal of it to save money, plus we just wanted to be able to look at the finished project and feel as though we were at least partially responsible for the results. Fortunately, we have a pro looking over our shoulder—Jake Brazille of Jake's Place in Florence, Oregon, is keeping us from making any major mistakes and will be the man with the gun when the spraying commences.
Some time ago the body of our Plymouth was chemically stripped, new floors were installed, and the preliminary bodywork was done. Then as often happens with our projects, it sat, then it sat some more, while other responsibilities got in the way. But when our once-pristine Plymouth sheetmetal began to develop minor surface rust it was obviously time to get serious.
Fortunately the protective coating that had been applied after stripping had, for the most part, done its job. But, like the rust that was forming, it had to be removed as well, so we went over the entire body with 150-grit paper on a dual-action sander and red abrasive pads. There were some areas that were difficult to reach, like the rain gutters and the recess around the trunklid, so we resorted to abrasive pads on a die grinder and a small handheld sand blaster from Harbor Freight.
We're going to keep this short and to the point: Don't mix products from different suppliers as compatibility can be a serious problem. When it comes to thinners, reducers, activators, and clearcoats don't fall for the "this is just as good as the name brand" sales pitch. There are a number of cheaper "universal" products on the market but refinish materials are a great example of getting what you pay for. To make sure all our efforts to get the RamRodder ready for paint won't be wasted, we'll be using PPG products exclusively.
After sanding and a thorough cleaning with DX440 wax and grease remover, we put down a coat of DPLF Epoxy Primer. This product provides excellent adhesion and rust protection when applied to properly prepared metal. DPLF Epoxy Primer may also be used as a sealer and topcoated with most PPG Refinish products. It comes in six colors: DP40LF (Gray-Green), DP48LF (White), DP50LF (Gray), DP60LF (Blue), DP74LF (Red Oxide), and DP90LF (Black).
The function of primer is to give the paint something to adhere to, not to fill minor imperfections. For that reason there is no advantage to heavy coats of primer; in fact it should be avoided.
Unless the bare bodywork is laser straight, the way to get it that way is with primer surfacer. These products will build a thick film quickly and allow for block sanding to get rid of surface irregularities and provide a super-straight base for the topcoat. As we've said before, if the car is not straight in primer, it won't get any better with paint.
We chose PPG's D839 2K Primer Surfacer for its versatility. By simply adjusting the amount of thinner, D839 can be as a conventional primer surfacer or as high-build spray filler.
There are two basic types of spray guns, gravity and siphon fed. The gravity style has the cup mounted on top of the gun while the siphon type has the cup mounted underneath.
Today the most common type of spray gun is the gravity-fed, high-volume, low-pressure design (HVLP). These paint guns pass a high volume of paint through a nozzle at a lower pressure (as low as 10 psi at the air cap compared to a regular gun that may require air pressure of 60 psi or more). HVLP paint guns are much more efficient than the siphon type. The low operating pressure results in far less overspray, which means less wasted material.
Our gravity-fed HVLP gun is a Concourse from Eastwood that uses just 4 cfm at 29 psi. The gun came with two additional fluid tip/needle combinations. Eastwood recommends a 1.3-1.5mm fluid tip for lacquers, enamels, urethanes, basecoats, and clearcoats; a 1.0mm fluid tip for water-based automotive paints and a 1.8-2.2 tip for heavy paints and primers.
When it comes to painting be aware that in some parts of the country there are strict guidelines for the use and application of such products—so check with the local authorities first before you decide to squirt your car at home.
So, What's Next?
Two words: block sanding. So far we've applied a single coat of DP90LF and two coats of D839. In our next installment we will show what it takes to find and fix any remaining imperfections and get ready for color. It will definitely be another milestone.