Underbody In Primer

As I had hoped, I was able to get most all of the underside of the car back in epoxy primer today. There are a few spots I missed, and I ran out of time to finish them, but I have a one week window to recoat, so I will be able to do some touch-ups at the beginning of next week.

I started out after getting to the shop this morning by getting the car tilted up well on its side on the rotisserie. I don't care what else the rotisserie has helped me accomplish up to this point, just having it for the painting task made it worth it! This made access to the bottom of the floor pan and battery box super easy.

Then I set up the work area. Yesterday, before leaving, I got the area underneath the car covered with a 4mm sheet of plastic. This is thick enough to take some minor abuse and not rip immediately. It was also large enough to cover up the surrounding tools and other stuff in my work area so that they wouldn't get covered in overspray.

There was a customer car adjacent to mine that was in for some work; I covered it in plastic painting drop-cloths and taped it down so it would stay clean and I wouldn't be buying anyone a new paint job. I set up a heavy duty exhaust fan at the garage door entrance of my work-bay, so that overspray would be sucked out of the garage. Now, this whole setup is very amateur and would not be sufficient for doing a paint job on the top of the car. There is too much chance for dust settling on the surface, and things really need to be closed up more for that. However, just for sealing the underside with epoxy primer, it was sufficient.

I then proceeded to wipe down everything again with PPG DX330 solvent. This is the recommended solvent to use before painting. It smells just like mineral spirits and that is probably the major component. The fenders were still greasy and oily in spots, and I simply wasn't able to get all the old undercoat and rustproofing agent removed. Oh well, it is still doing its original job. All the times I have removed the rustproofing agent, the metal underneath has been in good shape. It is just a total mess because it is in a semi-liquid state. I got off some more and had to be satisfied.

For painting, I wore a full length tyvek paint suit with elastic cuffs. Very hot and stuffy, but required to keep paint off my body/clothes, and to avoid isocyanates present in the paint entering into my skin. I chose to wear a full face 3M respirator specifically marketed for automotive refinishing.

While many people today advocate only a supplied air system for automotive painting because of the risk of isocyanate exposure, a respirator with fresh organic vapor cartridges should technically be safe, unless you are in a room totally opaque with overspray fumes. I never smelled any paint while using my respirator today, until I removed it. This was a full face model (how sexy, baby!) that makes you look like you are about to deal with Ebola virus or something, but it isn't made for looks. Please, Please, Please, if you are considering doing any work like this, read up on the dangers of painting with automotive paints, and take necessary safety precautions. You only have one set of lungs. You can always get another paint job. Don't buy expensive paint and then cheap out on personal protection!

I rigged up my Harbor Freight HVLP gun. My arrangement was to feed shop air into a water separator, followed by a coalescing particle filter. Dee had both of these mounted on a portable rig that he loaned me. Then, Exiting this apparatus, I hooked up my paint hose, which led to the gun. Entering the gun, I mounted a "final chance" water separating filter. On top of that was the gun pressure regulator leading into the gun itself. If you are doing any painting, I suggest you have at least this sort of moisture removal set-up. I was able to catch pretty much all moisture with this system.

Pressure on the gun was set to 40 PSI with the trigger pulled. I then took the gun over to my filling station and mixed up 1/2 qt. of DP40. I didn't use any reducer, even though a 2 parts paint : 1 part activator : 1/2 part reducer ratio is permissable. This was on the suggestion of messages I read at http://www.autobodystore.com's Painting and Refinishing Forum. If you are interested in doing any paint or bodywork yourself, do yourself a favor and check it out.

After thorough mixing, I put the paint in the gun. I sprayed the gun on a large piece of cardboard to adjust the fan pattern and amount of paint coming out. Then I moved on to the car. I started by spraying a coat on the floorpan, followed up by the bottom of the battery box. By this point, I had run out of paint, so this time I mixed up a full quart of mixed paint. Dee also came in and said I was spraying out too much paint, and was amazed I hadn't had a major run. We dialed back the amount of paint coming out. Following this, I painted the rear seat area, then the bottom of the engine compartment, and then the fenders. Many parts of the fenders were quite difficult to get inside because of the overall length of the gun configuration. With the paint cup on top, and the regulator and water trap on the bottom, it isn't easy to get into tight spots. Also, without a liner cup system, spraying at extreme angles or upside down is pretty much impossible...the gun just starts spitting and then spraying only air.

After doing a second coat on everywhere but the undersides of the fender areas, I rotated the rotisserie and put the car back upright. Painting the parts of the fenders that I missed was easier in this configuration. I ran out of time, however, and had to stop. I got most of the underside finished, using 1 qt. unreduced DP40LF total. I didn't do the inside of the battery box, the top of the floor pan, or the top/inside of the engine compartment. Those will have to wait for next week.

I cleaned up the paint cup with lacquer thinner, sprayed the gun clean with lacquer thinner, and cleaned the cap and needle. I think I started spraying at 2:30 and I finished at 4:15. Next time will be faster, I was doing everything for the first time today and had to go slowly and carefully.

I didn't even have time to stick around and see the results totally dry, but my first impression was that the job was quite good and I am pleased. After all these months, the bottom of the car has really come together, and this primer job makes it look nice and homogeneous. It is getting much more difficult to pick out the repaired spots, which is exactly the idea! Posted by pbrown at August 5, 2004 10:33 PM