"Painting and Woodgraining" - Part 7
After last month's article on "finish painting", we received letters asking for more on the subject. Our experience is with the suction-fed gun. We use separate Binks #7s for primer and for paint. It is best to have two guns; one for paint and one for primer. Primers are highly abrasive and will eat up the inside of your "paint gun". There are five factors in controlling your paint gun: 1. air pressure at the gun, 2. adjustment of spray pattern, 3. material flow, 4. gun speed, 5. distance from the panel to be painted. To set the air pressure, it is best to go by the instructions on the paint can. Enamels need 55 lbs. And lacquer and lacquer-based vinyl sprays need 35 lbs. The spray pattern should be a solid oval shape in either horizontal or vertical setting. This is called the "fan" (see fig. 1). For a horizontal pattern, set the air cap vertical, and for a vertical pattern, set the cap horizontal. Next, adjust the material flow so that it fills but doesn't run as you move your gun. The gun speed is approximately one foot per second and the fun should be held about 8" from the panel. We also recommend using a dripless paint cup. This will help to eliminate paint drips from the air hole in the paint cup (a hard lesson I learned while painting the trunk lid on my '46 Packard!).
Thoroughly mix your paint-in a "paint shaker" if possible. This is especially important if you are using metallic paint. After mixing, use a paint strainer as you pour the paint into the gun's paint cup. Test your spray pattern once more by spraying onto a piece of making paper. As you begin to paint, keep the gun parallel to the panel at all times, being careful not to fan out at the end of your stroke. The idea is to keep the paint going on in a solid, uniform spray instead of misting out at the edges.
For enamels, put on a light first coat, let it become tacky, then add your color coats. If you are using one of the new two-part primers, most require sealers. I have tried to paint over them without sealing them, and found it takes twice as much paint to cover. Ask your supplier about these products. When building color coats, we cross-coat, painting each coat at right angles to the previous coat. This helps eliminate runs. If you get a run, don't wipe it off! Let it dry, then sand it out and touch up.
After the last color coat, we let it dry, color sand it with 400 for enamels or 600 for lacquers, and spray one last coat of color, slightly over-thinned (we use hardener with all acrylic enamel). This leaves an OEM finish with just a little texture-good shine, but not too much. When the paint dries, it is ready for compounding (to be covered in future issues).
Another important part of painting is masking and taping. We recommend using a good grade of masking paper. Using newspaper can result in bleed-through, leaving the latest headline printed on the side of your car. For a very sharp tape line, we use 3M Fine Line #06303. For circles and curve taping, it's Dupont#471. When taping around rubber parts, clean with Acryliclean so that the tape will stick. It is generally safe to remove masking tape after about one hour with lacquer, or 6 hours with enamels. Being able to paint your own car will give you a feeling of pride and the ability to touch up those scratches that you will get by driving old cars.
Another project we worked on this month was woodgraining the interior mouldings in our '36 Packard Rumble Seat Coupe (see Issue #8), a process popular on most cars of the 30's and 40's, designed to look like wood. It was generally a decal transfer process, but a very nice look can be achieved by hand-painting.
The first step is to determine what a kind of wood is being simulated. If the dash has been painted, as was the case of our car, remove the dash, look under the glove box hinges, under ash trays, etc., for a sample of the original woodgrain color. Ours was "Carpathian Elm", a dark wood, and the backside of the dash provided a sample of the base color-a medium brown. This base color was used on many of the cars (see formula at the end of the article). This is an enamel, so lacquer should not be used over it. We use artist oil paints and black printing ink. Colors: Raw Sienna, Burnt Sienna, Yellow Oxide, Perylene Maroon, Black Printer's ink and a wood stain. Most any wood can be simulated from these colors. It is important to use high-quality oil brushes ranging in size from a fine liner to a 2" wide brush. I stress high quality, because you don't want to achieve the perfect grain only to find a brush hair stuck in it!
After the base coat has thoroughly dried, mix some oil stain. We used Minwax oil-base "Jacobean" #2750 with the artist colors (keep it thin). Brush on and start working, If you want a straight grain, use the wide brush, moving left to right with an occasional up/down ripple in the grain. Use one of your smaller brushes to put in darker grain accent details. Dry bristles work better for heavier grains. It just takes practice, and since the stain doesn't dry fast, if you don't get what you want the first time, just do it again.
If you want a burled walnut effect, we have had excellent results using a natural sea sponge to stipple on the paint. Natural sponge has a more interesting texture than man-made has, and they are available at art stores. Just dip the sponge in the stain mixture
And dab onto the panel. You can get a believable wood effect by twisting or pulling the sponge on the panel. Again, practice is the key. For more depth, you can put a dot of black here and there with your detail brush. When you're satisfied, let it dry at least 24 hours, then clear coat (we use Dupont Centauri Clear #780S with 782S activator, 4-5 coats, waiting 20 minutes between coats). If dust falls into the clear, let it dry, then sand with 1200 grit and re-spray. We always use correct respirators, gloves and all protective gear that is called for on your paint cans. And remember-paints can be absorbed through your skin!
We put the moulding on in about a week and wait a total of three weeks before hand-polishing with Finesse-it. This result is beautiful and very close to the original. See you next month!