Epoxy primer has been on the...
Epoxy primer has been on the Track T for several months, therefore it had to be scuffed up before any additional substrates were added.
(Editor's note: Dennis Parks is a longtime contributor to STREET RODDER so it was with no surprise when we were reading his new book Hot Rod Body and Chassis Builder's Guide, offered by Motorbooks International (www.motorbooks.com), that we came upon a chapter on paint prep and realized this was great information for all STREET RODDER readers.)
Lots of hot rodders want to know how to paint their cars. Since painting is such a popular topic, virtually every automobile magazine does at least one paint special a year, and this is the month for STREET RODDER. Oftentimes rodders fail to realize the physical act of painting is relatively simple and a small portion of the overall success of a paintjob.
The truth is surface preparation is the key to a good paintjob. No matter who squeezes the trigger, what brand or color, or what make or model vehicle it is going on, if the surface preparation is less than "perfect," the paintjob can't be greater than the preparation.
Scuffing the epoxy primer...
Scuffing the epoxy primer serves as a good opportunity to check for and note any areas that may need additional attention.
Regardless of the countless hours you spent modifying your hot rod's body, you should take the time to make sure the rest of the body is as perfect as it can be prior to painting. Now is the time to locate all of the little (or not so little) dents, dings, and scratches.
Filling Low Spots
Most minor dings and other low spots can be eliminated. If you have access to the back side of the panel, use a body hammer and gently work the ding back out so that a minimal amount of body filler is required. If the dent is less than about 1/8-inch deep it can be eliminated with body filler. Begin by scuffing the paint in the area to be filled down to bare metal or epoxy primer. If you have multiple dents to fill, remove the paint from all the divots. Scoop an appropriate amount of body filler onto a mixing board. Don't mix more than you can apply before it will begin to set up. Use a plastic spreader to apply the filler to the dent, using a wiping motion in one direction across the dent. If done properly, the filler will stay in the dent and wipe off the area around it. Use this same method to fill the rest of the dents.
For sanding large flat areas,...
For sanding large flat areas, a long board sander can't be beat.
After the filler begins to cure, use some 50- or 80-grit sandpaper on a sanding block to knock off any high spots. If you leave a gouge in the filler, it needs some additional time to cure. If sanding causes dust, you can continue sanding until the dent is sanded down to the correct level. If necessary, a second coat of filler may be applied to completely fill the area. After rough shaping with 50- or 80-grit sandpaper, use 140- or 180-grit sandpaper to blend into the surrounding area.
To ensure that I didn't bend...
To ensure that I didn't bend the hood sides while sanding, I supported them with scrap pieces of oak flooring while sanding.
Sanding too much is relatively unheard of; sanding incorrectly is more common. It's not readily noticeable during the primer coat phase but spray on a glossy coat of paint and incorrect sanding will quickly become apparent. As long as your techniques include using a sanding block or board, using the appropriate grit sandpaper, and sanding in an "X" pattern, sanding is easy. However, all too often the amateur bodyman cuts corners, only to minimize the positive effects of his hard work.
Using the palm of your hand and not the proper sanding block or board leads to poor results. For sanding to be done efficiently, the sandpaper must make full, even contact with the surface. Even though your hand can move the sandpaper across the body surface, more pressure will be applied at the knuckles and less pressure applied at the palm. This will cause waves in the panel due to the uneven pressure of the sandpaper as it crosses the body surface.
The appropriate grit sandpaper is determined by whether you are smoothing body filler, color sanding paint, or somewhere in between. Each step of the bodywork process has a range of sandpaper grits that are appropriate for that particular step.