203 Chapter 9 Nonstructural Panel Repair Copyright Goodheart-Willcox Co., Inc. from the pinholes. Pinholes can be corrected with an application of putty. Use 180-grit sandpaper to feather- edge the pinholes before filling. To minimize sanding, use a razor blade to apply the putty. The sharp edge of the razor blade will fill the pinhole with putty and remove the excess. After the putty has cured, the filler is sanded with 180-grit sandpaper. To prevent prob- lems, use high-quality filler. Mix it properly and observe the recommended cure times. Using Lead Filler Lead filler was commonly used to repair dents in vehicles before the invention of body filler. It still has a place in body repair. Some technicians use lead filler on a repaired panel edge, such as the edge of a quarter panel adjacent to a door. The lead filler is less likely to chip off if the panel edge is hit. Lead filler is supplied in sticks. The sticks have a lead/tin ratio of 70/30 or 60/40. The 70/30 sticks are more expensive, but they are easier to apply. The key to applying lead is learning to control the heat used to soften the lead stick. Lead that is heated too much will melt and run off the panel, rendering it useless. Heat the lead stick just enough to soften it, but not enough to melt it. The lead stick will change from a dull silver color to a bright and shiny silver as it melts. Avoid heating the lead stick to the shiny stage. As with body filler, do not try to fill areas deeper than 1/8” with lead, as this simply saves on the cost of materials. Lead filler application is easier on a horizontal surface than a vertical surface. On a vertical surface, gravity is constantly trying to pull the softened lead filler down and out of the fill area. Lead is a toxic substance. Wear gloves when handling lead products. When melting lead, work in a well-ventilated area and wear approved respiratory protective equipment to prevent inhalation of lead dust or vapors. Wash your hands thoroughly after handling lead or working in a lead- contaminated area. There are five distinct steps in lead filler application: • Stripping. • Tinning. • Heating. • Applying. • Smoothing. To begin the lead filling process, remove the paint from the panel surrounding the area to be filled. The paint must be removed from the entire area to be heated. An area at least 5-6 times the size of the fill area will be heated. The fill area must be prepared before the lead is applied. This process is called tinning. During tinning, a liquid flux is applied to the fill area. The flux cleans the bare metal and prepares it for the application of lead. After the flux is applied, the fill area and the entire bare metal area are gradually heated. A propane torch or an oxyacetylene torch with a special tip that burns only acetylene must be used to heat the metal. The metal is heated enough that the lead stick softens and adheres to the panel when touched to the heated metal. If the metal is too hot, the lead will melt and run off the panel. Use steel wool or a rag to wipe the excess lead off the fill area. After tinning the repair area, the filler can be applied. Two things must happen during the application step. The bare metal and fill areas must be kept hot, but not hot enough to melt off the lead in the tinned WARNING Goodheart-Willcox Publisher Figure 9-62. This curved body line was formed with masking tape. Goodheart-Willcox Publisher Figure 9-63. This cured body filler has numerous pinholes and scratches. Pinholes