Mustang MonthlyHow To Paint Body
Paint Chip Repair
Make a Quality Paint-Chip Repair: How to fix the brain-dead belt-buckle incident
So the other day, I broke my own cardinal rule and got a belt buckle too close to a customer’s car. You’re right. I chipped the paint. Let’s turn a tragedy into a teaching moment and talk about paint-chip repair on a classic car. First, there’s a big difference between repairing a chip in your classic Mustang and repairing one on the minivan where you just tapped the garbage can gunning it out of the garage. You don’t want anyone to know the paint chip ever happened to your Mustang, but it’s a 20-footer repair for the minivan. You’ll probably just do it again next week. Sadly, I have seen many a show car with mismatched touchup paint after someone used a generic paint touchup bottle that made it look like the car had caught a bad rash. Here’s how to avoid that look.
The type of paint you use affects the outcome of your repair.
The paint used on your car is a catalyzed paint, which means it is mixed with a hardener to increase its strength. Pre-mixed touchup paint is not catalyzed and will be softer than the paint on your car now. As a result, the repair is softer than the original and may age differently and heat up faster than the surrounding paint when you’re polishing and buffing. You can use non-catalyzed paint, just note this fact before hand. You may also have to plan on cutting and buffing by hand. If you have leftover paint from when the car was painted, try to get the catalyst and mix it up before applying.
Everyone online tells you to go to the local paint store, have it bring out its color computer, and zap your car. Then, voila! You have matched paint. Not true. The computer color analyzer can only give recommendations based on what is stored in its memory for previously mixed paint codes. These codes are only an approximation, though. Many of the paint supplier brands weren’t around 50 years ago, so color matching is a best guess (for instance, Grabber Blue comes up as a BMW color on some systems). The computer is only a start. The older your paint is, the harder it is to match. Original paint from the ’60s not only varied widely back then, but after 50-plus years, it will not be the same color it was, even if you stored it inside. The older the paintjob, the cruder the technology used to mix the paint, and so, the harder it is to match (if you painted your car a 2015 color, you have a better chance of matching it). Even if you do have some of the paint left over from a restoration, the paint on your car may have faded, and you may need to have the original paint tinted to match. On top of that, the mixing bank materials change frequently. For instance, the size and shape of the aluminum used in the metallic paints changes and greatly affects the look of the paint. Metallic paint is much harder to match due to this, and much harder to apply to get the metallic to look right. Paints generally darken as they dry, so you can’t see if it is a match until it fully cures.
Our favorite paint supplier is very good at matching, if given time. We usually take a painted part to them (end caps work great), and let them blend it over a couple of days (letting it dry out completely). On our red car, they were able to get the mix right on the money.
Single Stage Versus Clear Coat:
Some people can tell the difference between single stage and clear coat on the car. They do have a different look. If you need to determine what type of paint is on your car, you can carefully apply 2,000-grit wet sandpaper to an inconspicuous area and lightly wet sand the paint. If the residue is a milky color, it is a base or clear. If you see paint color, it is a single stage. Re-polish and buff the paint carefully and be sure not to cut through to the base.
Wash and dry the car. Before sanding, use a good degreaser and de-waxer on the area to be repaired. Although general degreasing products are available at local stores, I recommend using an automotive-based product, such as DuPont Lacquer and Enamel Cleaner 3939S, Prep-Sol and Final Klean, or anything made by your paint manufacturer will work as well. These products are made for automotive paint, and you don’t want to cause a reaction with a generic cleaner.
Inspect the chip, and see how deep it went. If it went all the way down to the bare metal, apply a little primer to the area to give your paint something to grip to. If it went down to the primer, scuff the area, and you are ready to go. A fiber spot sander is inexpensive and works great for taking the edges off the chip and smoothing the area before you paint. If you are careful, you can also use some sandpaper and the end of an eraser or a Q-tip to gently blend the area.
How you apply the paint depends on your preference. You can use a small artist brush. Just make sure it is a good one that won’t leave bristles in your paint. A plastic toothpick mimics the capillary effect you find in the new touchup paint systems. The small amount of paint draws down to the surface without running over the chip area. Wooden toothpicks are porous, and they will work just not as well as the plastic one. Take your time and allow the paint to completely dry before going to the next step. With metallic paint, it takes time to see if the aluminum or Mylar is lying down properly.
Sanding and Buffing
You are blobbing paint on to the surface, so it needs to be leveled out if you want it to blend properly. Some online resources recommend using between 320- to 2,000-grit sandpaper to accomplish this. I advise exactly the opposite. Don’t ever use a grit grade of sandpaper that can’t be buffed out. Use the finer-grade sandpaper first. Even a well-painted car may have thin areas and going at the paint with coarse paper will cut through much easier. It works better to use finer paper and take a little longer to cut the tops, rather than risk getting a cut through on the surrounding paint. Use very light pressure, and check it often. If you cut through the clear, you will see body color on a base and clear paint job, and you will get a nice halo around the repair area. The key is to go slow.
Take care with buffing and polishing. The heat of a machine buffer can heat up the non-catalyzed paint and discolor it very quickly. You can compound and polish by hand on air-dried paint to help avoid this.
Most problems arise due to rushing the job. Unlike the minivan that needs to be available for work in the morning, it’s best to take your time on your Mustang. Once you get your paints matched to your paintjob properly, make up an emergency touchup bottle to use at shows and on the road (paint suppliers sell small touchup bottles). Mix a little clear and color together, and even catalyzed paint will eventually air dry. You can repair it properly when you get home.
1. Road debris, belt buckles, and inconsiderate onlookers are your paint's worst enemy. Chips are going to happen. Here is how to make quality long-term paint chip repairs.
2. Touchup paint has always been available, and the car generally looked horrible after using one. The more modern paint applicator comes all in one: fiber sander, base, and clear all in one tube, computer mixed for better accuracy. It is still an air-dry paint and may not match perfectly, especially with metallic paints.
3. Some quick tips on mixing and applying paint: Use old medicine cups to measure out small amounts of paint, and an eyedropper is great for mixing super small amounts of catalyst and paint. Plastic toothpicks allow a capillary effect to draw the paint to the car. These yellow applicators can be purchased at auto paint stores and have a lint free end. They work great for applying paint and mixing the small amounts you put together with the eyedropper. In a pinch, a regular brush works to apply paint. Pens filled with primer are available if your chip is down to the metal, and a fiber sander pen preps the chip area well.
4. After cleaning and degreasing, use a fiber pen or a small piece of sandpaper to smooth the edges off of the chipped area. Use a rotating motion around the chip area and be extremely cautious not to cut too deeply into the surrounding paint.
5. If your chip went down to bare metal, you can mix up primer, if you have it, or buy a touchup pen with primer. The primer gives your paint a base to grip onto.
6. The first red from the computer didn’t match, so I took an end cap over to my paint mixer. She worked on it for a day or two and got an exact match. Paint tends to dry darker, so she needed time to adjust.
7. Here, I am using a plastic toothpick to apply the basecoat, which allows my to draw the paint down onto the surface. Unless you are forcing it, it won’t run over the sides of the repair area. Let it dry completely. It may take several applications.
8. For the clear, I prefer these small paint applicators, which have a tiny lint-free daub at the end. Don’t use Q-tips, as this will leave fibers in the paint.
9. For small areas, I use a small piece of a paint stick. For curved areas, a small eraser works nicely. I recommend using fine sandpaper like 2,000 grit and take more time to be careful, rather than starting aggressively and working back.
10. Use very light pressure and go slowly when leveling the paint. It is very easy to cut through, and one of the reason you may have a chip is that the paint may be thin in that area to begin with.
11. For a catalyzed paint, use a machine buffer to smooth your sanding marks. If you used an air-dry paint, I recommend compounding and polishing by hand.
12. The damaged area is repaired but won’t stick out at the next car show. I mixed a small bottle for the customer, so they have an emergency repair bottle if something should happen in the future.