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Body Repair And Primer - Filling TimeFrom the August, 2012 issue of Rod & Custom By Kev Elliott
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[1] Summit Racing supplied... [1] Summit Racing supplied all the consumables to tackle the bodywork: Evercoat Rage Gold filler, DA discs in 40-, 80-, and 150-grit, and a roll of longboard sandpaper in 80-grit. Paint your own car. That scared you, huh? But why not? If you can build a car from the ground up it’s a safe bet you already mastered techniques like welding and fabrication. You probably already have a compressor in your home shop too. One of the most common questions regarding spraying a car at home is the legality. Sure some paints are illegal in some states, notably California, but it can be done. It’s also complicated isn’t it? Well, it doesn’t have to be. Especially not with Summit Racing’s Paint and Auto Refinish System. They’ve taken all the mystery out of the process. No longer do you have to go into your local paint supply house, if you even have one in your town, and wonder what it all means. The Summit system is easy to follow, has a variety of reducers to work at different temperatures, and is available in basecoat/clearcoat or single-stage versions (meaning no clear is required). There’s also a range of primers and sealers, and Summit Racing doesn’t just sell paint, they sell everything required to tackle bodywork. We ordered body filler, polyester putty, a paint starter kit (comprising masking paper and tape, mixing cups, paint sticks, gun filters, tack rags, and strainer) as well as a new spray mask and suit. Check out the range at www.summitracing.com. [2] DA discs are available... [2] DA discs are available in two styles depending on your backing pad. A hook-and-loop Velcro-style is available, but I prefer to use the self-adhesive type. Generally more cost-effective, their only disadvantage is that they are not reusable. Project Purple Pig is finally ready for body and paint, so we turned to Summit for everything we needed. It was sure nice to have everything arrive in a couple of boxes rather than make repeated trips to the supply house. We’ll not be painting the Chevy just yet, as we want to drive it a while to iron out any bugs, but we’ll show you how to apply filler, sand it, and lay on high build primer. Any paintjob is only as good as the prep beneath it. Speaking of what’s beneath the paint, I prefer to apply filler over bare metal. With the cars we mess with, any paint is probably several decades old, and if I’m going to spend good money on materials, I want them to stay on the car, so I start with fresh steel, or ’glass. Applying filler over old paint not only relies on the paint’s adhesion but may cause shrinkage marks in your final topcoat later on. I should mention that I used to be a bodyman, and modern techniques have probably changed since [3] My personal preference... [3] My personal preference is to apply body filler over bare steel, and to prep the surface with 40-grit pads. Ensure you wear a quality particle mask while sanding filler, paint, or bare metal. I switched professions, plus everyone has their own techniques, so the following is just “my” way of doing things. It’s the way I’ve always done it, and it works for me. Modern primers can have filler applied over them, and in fact you’ll see I have done just this over some old primer on the roof of the ’49, but I sprayed that primer, I know what it is, and I know what’s under it! I prefer to use a DA (dual action) air sander with 40-grit discs to prep the metal, though 80-grit could be used. It should be stressed that body filler is not intended as a cure for deep dents or rust, but as a skim coat over well-repaired body panels. If your filler is more than 1/8-inch thick, it’s too thick! Once the panels are sanded and blown clean using an air gun, it’s time for that skim coat. On opening the tin of filler, you’ll probably see a honey-like resin layer on top. This just means the components have separated during storage, so stir the filler with a paint mixing stick until it achieves consistency throughout. You may also find the filler is thicker at the bottom of the tin at first. While cardboard is often used for mixing filler on, it absorbs some of the resin, so use a plastic or glass mixing board. [4] Experience will tell you... [4] Experience will tell you how much filler to mix at one time, but try to mix no more than you’ll need, adding the appropriate amount of hardener. Too much and it’ll harden too quickly, not enough and it’ll never harden. It’ll also harden quicker at higher temperatures. The accompanying captions explain how to mix and apply filler, but try to spread it smoothly and over the entire area to be repaired. If you find you need to add filler in some areas after sanding, re-apply a spread over the whole area, not just the low section, as it’ll make it way easier to block it flat than trying to block an area of fresh filler in the middle of already-sanded filler, as you’ll always end up sanding the new and the old. Oh, and while it may look like there’s a lot of filler on the Chevy, the gallon can was enough to cover all the repairs seen on both sides of the car. A thin skim can go a long way!  [5] Using a filler spreader,...  [5] Using a filler spreader, mix the hardener into the filler until it’s a uniform color, then remove any unmixed filler from the spreader using a clean rag or shop towel.  [6] Mix the filler slowly,...  [6] Mix the filler slowly, or you’ll get air pockets. I purposefully mixed this batch quickly to illustrate that. The arrows indicate the air bubbles, which will transfer to the panel the filler is applied to. They may be slightly under the surface and undetectable until they blister through the finished paintwork at a later date. Small air bubbles, which will appear as pinholes in the sanded filler, are unavoidable and can be filled with putty prior to primer, but large ones will ruin all your good work.  [7] Always try to spread the...  [7] Always try to spread the filler as smoothly as possible, as it’ll make sanding so much easier. Also, though spreading a large area at once may seem daunting at first, attempt to cover the whole section you’re working on, as filling small sections always seems to result in low spots where areas of filler applied at different times meet. You’ll sand more off this way, but it’s actually easier.  [8] If you remember, I welded...  [8] If you remember, I welded lower repair sections to the rear quarters of the ’49, and the top of the driver side panel was warped from previous bad repairs. This illustrates what I mean by spreading filler over the entire section. As it was such a large area, and I didn’t want the filler to set before I was done; this isn’t the neatest spread I’ve ever done!  [9] Before the filler completely...  [9] Before the filler completely cures, a rasp can be used to rough out the repair, saving time sanding later. This is the rocker panel, which again, was completely spread, though most will end up on the floor.  [10] Whether sanding with...  [10] Whether sanding with a DA or by hand, stop frequently and run your hand over the area to check for high/low spots. Don’t use your fingers—you’ll get a better feel for the surface using your palm.  [11] I sanded the entire quarter-panel...  [11] I sanded the entire quarter-panel with the DA using 40-grit, leaving the filler slightly higher than required as I’ll use finer grit by hand to take it down to its final finish. When you start to see spots of metal showing through, it means you either have high spots you didn’t repair correctly at the hammer and dolly stage, or you’re approaching the hand-blocking stage. Hopefully it’s the latter!  [12] Though I have an arsenal...  [12] Though I have an arsenal of sanding blocks, I use this trio most frequently. Removing the metal rods transforms them from rigid to flexible, as we’ll see.  [13] The larger two blocks...  [13] The larger two blocks have a metal face, which the self-adhesive sandpaper sticks to, as seen here. I’m now switching to 80-grit paper.  [14] Using the long-block,...  [14] Using the long-block, with the metal rods inserted, the quarter-panel was sanded in a cross-hatch manner.  [15] With the rods removed,...  [15] With the rods removed, the same block was used to sand the hip section of the panel, again in a crosshatch manner, which eliminates the possibility of flat spots.  [16] The medium-sized block,...  [16] The medium-sized block, minus the rods, was ideal for sanding the inner fender lip.  [17] Once sanded with 80-grit,...  [17] Once sanded with 80-grit, you’ll note how many more areas of metal are showing through. Almost there now.  [18] You may remember I had...  [18] You may remember I had to remove small vertical sections from the leading edge of each quarter when I was gapping the body panels a few months ago. With a skim of filler applied to the panel and inside the door shut, wrapping 80-grit around a paint mixing stick ensured the gaps would be even. Don’t be afraid to use whatever will work as a block. Old radiator hoses make excellent blocks for curved areas, for instance. Just make sure they’re clean and free of oil, grease, or silicone.  [19] The ’49 Chevy has a body...  [19] The ’49 Chevy has a body line under the beltline trim that extends from the A-pillar, through the doors, and around under the rear window. This required extensive surgery during the roof chop as it had to be laid down around the rear of the roof. I cut a filler spreader to the shape of the body line to apply filler here.  [20] With filler applied and...  [20] With filler applied and sanded above and below the beltline, I could use the modified spreader on the body line.  [21] With masking tape as...  [21] With masking tape as a guide, I again wrapped 80-grit around a mixing stick to sand the body line and achieve a crisp edge.  [22] This was the hardest...  [22] This was the hardest part of the whole job to get right, but once primed, blocked, and primed again, it’ll look like it came from the factory this way! All the repaired areas were now finished with 150-grit paper by hand.  [23] Throughout the quarter-panel...  [23] Throughout the quarter-panel repair I used a factory fender skirt as a guide, both while fitting the repair panels to achieve the correct curvature, and when applying the filler. The tape shows where the gap needs a little more work to be uniform. Though I doubt I’ll run skirts, I welded the tabs and mounts in place so I have the option.  [24] This is Summit Racing’s...  [24] This is Summit Racing’s painter’s starter kit, comprised of masking paper in three different widths, masking tape (some of which I’d used prior to snapping this pic), mixing sticks, paint strainers, mixing cups, tack cloths, and water filters for the spray gun. [24] This is Summit Racing’s... [24] This is Summit Racing’s painter’s starter kit, comprised of masking paper in three different widths, masking tape (some of which I’d used prior to snapping this pic), mixing sticks, paint strainers, mixing cups, tack cloths, and water filters for the spray gun.  [25] Wax and grease remover...  [25] Wax and grease remover was applied to the entire area to be primed, before any small particles of debris and dust were removed with a tack cloth.  [26] It may seem like you’re...  [26] It may seem like you’re nearly at the end, but getting to the primer stage is about halfway to a finished paintjob! I used Summit’s high-build DTM (direct to metal) primer, as it’s legal where I live.  [27] With the window and door...  [27] With the window and door apertures masked off to prevent overspray entering the car, it was finally time to prime. If you’re wondering why some of the filler is a different shade, it’s because I used varying amounts of hardener depending on the temperature at the time, which will affect the color.  [28] Here’s why strainers...  [28] Here’s why strainers are an excellent idea, even for primer. Despite rigorous stirring, there were still a few lumps of primer in the can. The paint settles during storage and transport, and these lumps will easily block a spray gun. Not so when a strainer is used!  [29] The mixing cups make...  [29] The mixing cups make it simple to add the correct amount of activator to the primer, using the ratios printed on the side.  [30] With the door latches...  [30] With the door latches removed, I masked the captive nuts prior to priming.  [31] Left overnight to cure,...  [31] Left overnight to cure, a guidecoat could now be applied and the primer blocked by hand. However, I’m going to assemble the car and shake it down prior to paint, so it’ll stay like this for a while. In case you’re wondering about the yellow primer on the roof, that’s also high build primer, applied after I chopped the roof many years ago.
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