Measure Twice, Byte Once Making Stuff

Dan’s House of Pain(t) – Part 2

Part One

Since I was now ready to paint, I started preparing my garage. I used a couple of 10'x20' plastic drop cloths to create a "paint booth". I also purchased a small space heater to help keep the garage warm. Winter is not the ideal time to be painting since the paint tends to need a temperature between 50 and 70 degrees Fahrenheit in order to dry properly. It's also very humid where I live in the Bay Area. We already had a dehumidifier which I moved to the garage to keep the humidity level down.

On painting day(a Sunday), I woke up early, removed the bumper cover, and moved it to the paint booth. I cleaned the entire surface with wax and grease remover. I then applied a few coats of adhesion promoter. This is a clear primer that is designed to help paint stick to different types of surfaces(including plastic). After letting the adhesion promoter dry for about 20 minutes, I started applying the primer. As I started priming, I noticed that the lighting in my garage isn't quite adequate for painting. In addition, I ran out of primer before finishing the second coat. The bumper cover had pretty good coverage, but there were still a few spots that definitely needed more primer. As it turns out, rubberized primer is not carried by any auto parts stores in my area, so I was out of luck trying to finish painting on the same day.

I recommend City Paints(in SF, near 7th and Folsom) if you live in the SF Bay Area and need auto paint. They carry a large variety of auto paint and auto care supplies. Prices were better than most of the online stores that I found. In addition, they will also fill aerosol cans with paint for around $11/can.

The following weekend, I cleaned the bumper cover again and started over with the painting. It turns out that wax & grease remover will eat through rubberized primer(and perhaps also regular primer), so be careful if you need to clean a primed surface. I applied three coats of primer and then wet-sanded with 400 grit paper.

I started out with the bumper cover supported by saw horses and facing up. It turns out that it's much easier to paint a vertical surface than a horizontal surface, especially with aerosol paint. I ended up using a rope to suspend the bumper cover from the ceiling for the color and clear coats.

I then applied color coats which I let dry overnight. The final color coat should not be sanded, but earlier color coats can be sanded. One of the issues with metallic colors is that the thickness of the color coat affects the final color and appearance of the paint job. If I were redoing the process, I would sand between the second and third color coats since there are a few areas where the paint ended up uneven. One of the issues with metallic colors is that the thickness of the color coat affects the final color and appearance of the paint job.

The following morning I applied four clear coats, let the bumper cover dry, and then put it back on the car. The clear coat has to dry for several days before it can be polished. An additional thirty days are required for drying before the surface can be waxed. The bumper cover color matches the rest of the car very well. In the interest of potentially saving money in the future, I also bought a can of Dupli-color paint from my local auto store. Dupli-color paint is around $7/can, whereas the paint I purchased from paintscratch.com was around $20/can. The Dupli-color paint also matches the car reasonably well, but the match is not quite as good as the paintscratch.com paint. Most people would probably not notice the difference in color unless it was pointed out to them.

I was able to complete the job with two cans each of primer, color, and clear coat. I would recommend three cans since two leaves a pretty small margin for error and repainting.

Since I was saving a fair amount of money by repairing the bumper cover myself, I was able to buy a nice auto polisher and supplies from Griot's Garage. A week after painting, I first wet-sanded with 1000 grit paper. I then used some aggressive polishing compound with the polisher to polish the bumper cover. This leaves a shiny surface, although it doesn't quite match the rest of the car in terms of shininess. I'm hoping that the eventual sealant and wax will take care of this issue.

Part One

Dan’s House of Pain(t) – Part 1

Part Two

It all started with a bang. My car was involved in a minor accident and sustained some damage to the bumper. The initial repair quote was a minimum of $800($200 for a new bumper and the remainder for labor). Rather than paying someone else to have fun fixing my car, I decided to do the work myself. In addition, since I wasn't driving the car at the time of the accident, the driver gets to pay for my new tools, supplies, and fun…perfect!

The first step was to assess the extent of the damage. The grille was partially broken during the accident and the Toyota emblem(expensive!) was lost. Although most people refer to the front of their cars as the "bumper", on newer cars this is technically just the bumper cover. The bumper cover is a thin piece of plastic that goes over a tubular steel structure and some supporting foam.

My bumper cover paint had been scraped down to bare plastic in a few places. The impact also forced the license plate into the bumper cover causing some deformation. It's also noticeable in the pictures that the bumper had been pushed in and no longer lined up with the headlights. I removed and cleaned the bumper cover and took a look at the supporting structures. On my car(2003 Camry), there is a horizontal metal support that runs between the headlights and under the top of the bumper cover. This support was clearly bent out of shape. There is an additional vertical support that runs up the center of radiator. This support also appeared to be bent in some way, but I was unable to determine how much. I attempted to straighten the horizontal support, but without a reference I was unable to make much progress. The first step then was to order a new horizontal support and grille. I was able to purchase the support and grille from autopartswarehouse.com for $58(including shipping).

Otherwise, the car appeared fine. Fortunately, the headlights were not broken since these tend to be expensive to replace.

I ordered a couple of books on auto restoration and painting and started doing some research. I wanted to determine if it would be possible to paint the bumper cover at home. Professionals use an air compressor and spray gun for paint jobs, but the average home air compressor can't do the job properly. However, it is possible to get matched auto paint in aerosol spray cans(paintscratch.com), which makes painting more feasible. As a result, I decided that I would repair and paint the bumper cover myself. As with any paint job, the secret to success(and the bulk of the effort) is in the preparation

Since the bumper cover is plastic, hammering out the dents wasn't an option. I would have to use a specially designed bumper filler(two-part epoxy) by 3M/Bondo to create a smooth surface. Many traditional auto repair fillers and primers cannot be used with bumper covers because these products are firm and bumper covers are flexible. If normal filler is used, it's possible that the entire repaired area may separate from the bumper cover when it flexes.

The filler only adheres adheres to plastic, so I used a random orbital sander with 100-grit sand paper to strip away the paint. As it turns out, It's slightly liberating the first time you take a sander to your car. Whether the car will look good at the end is something else entirely. I used an automotive wax + grease remover(smells like super rubbing alcohol) to prepare the surface for filling. There were a few areas that needed a fair amount of filler, so I ended up making the repairs over a few weekends and probably spent between 5 and 10 hours on this part of the project. The filler has a working time of a few minutes and is sandable after 20-30 minutes. I used a long, flexible sanding board to ensure that the filler that I was building up would match the overall curve of the bumper.

Eventually, I reached a point where the bumper was starting to look pretty good. There were still small holes in some places in the filler. I switched to using two-part glazing putty. This is initially much more fluid than the filler and can be spread to a much smoother finish. After a few rounds of putty + sanding, I was done with most of the repair work. I then wet-sanded with 220 grit paper to take out any leftover imperfections in the filled areas. I also wet-sanded the rest of the bumper cover, since new paint adheres better to a surface that has been scuffed.

Part Two