Now that we have the major bodywork out of the way (well, it was minor in the vast scheme of projects, but major to this car), we can focus our energies on getting the car painted. Rather, we can focus on getting the car ready to be painted.
Let's face it, the paint job is the first thing you look at when you first approach a car, and even though society suggests we don't, all people, at first glance, judge a book by the cover. Since, outside of Volkswagen circles, these little cars get a bad rap as slow and ugly (and even inside VW circles, Super Beetles get twice the bad rap), we want to make our paint job the best it can be...but we don't want to break the bank doing it.
This month, our attention is averted from us actually doing something to this car to showing you what you need to do to make your paint guy happy to work on your car and to make you happy with the results you get (if you can't afford to go to the best paint shop in the world, like us).
There is nothing wrong with the one-day places for a quick and inexpensive paint job. Granted, the paint is a lower quality than what the pricier shops use, but if you have a VW you don't plan on showing or driving too often--therefore keeping its exposure to the elements limited--there's nothing wrong with lower quality paint. However, there is something wrong with a low-quality paint job, and if you complain about it after the fact, it is no one's fault but your own. Quality paint jobs are quality in part because of the prep work, the bodywork, the sanding and the priming. That's what we're going to cover this month.
Photographically, this won't be too exciting, as one primered car is the same as another and the only difference is in the tactile feel of the more prepared car, something we can't show you in a magazine. But rest assured, after you sand, primer, paint and wet sand, you'll be intimately familiar with every subtle nuisance of every painted panel on your car.
But right now, it is a blank canvas.
After you are satisfied with the results of your bodywork, get up close and take a good look at the surfaces of your car. Since most all of our cars are at least 25 years old, odds are good slight imperfections have, over time, developed into something a little more evident than slight. It may be something as simple as a thumb print in wet paint or as complicated as a burrs on the surface from a previous weld job (we've got both).
The ultimate goal is to have a perfectly smooth and primered car ready to roll into the paint job, and in order for this to happen, you'll need a variety of specialty tools and several weekends of nothing better to do (make that weeks of you are an anal perfectionist).
There are two methods we could employ at this point: One is sanding and priming over the existing painted surface, and the other is to take the surfaces down to bare metal. They both have their advantages and disadvantages. Sanding existing paint is fine and is done by many a reputable shop, but preparation is all the key. If you don't properly scuff the old surface before applying the primer and new paint, over a short period of time (as early as a couple of weeks), the new paint will start to flake off because it doesn't have an absorbent base to adhere to. This is especially true if the old surface was baked on at the factory.
In order to scuff the old surface in preparation for the new one, a fine grade Scotch-Brite pad works best. The rough finish left behind is a perfect surface for primer or even to start with the base coat. Similarly, a 500- or 600-grit sand paper works best on shiny paint surfaces, and the results you are looking for is a dullness to the finish. There is no need to sand in one direction, as all directions work best to rough up the surface. The downside to this method is that if there are unseen blemishes under the paint (rust, trapped debris, etc.) you are just chasing good paint after bad and no sooner than you are done spraying the final coat do these blemishes transfer themselves up through the new paint.
The second method--take the car to bare metal--is beneficial because it gives you a clear picture of the metal's condition (and is necessary if your car's paint is lacquer based). You can remove any filler, see any hidden dents that need to be repaired and get a clean, fresh start. For the most part, we chose this method by accident, so it the one we will recommend. Over the years, our Super has been through its fair share of abuse--crashes, body panel replacements, dents--and we wanted to make sure that the car got a fresh start with a straight body and a clean paint job. Though it isn't easy, see the February 2003 edition of this series for the details, you may want to have the body media blasted or chemically dipped to remove any paint.
When you've completed all the bodywork and the panels are all straight and lined up with one another, it all has to be smooth. Walk around your Volkswagen and look closely at the details of the surface. Any imperfections you see now will only magnify when paint is applied. Run your fingers over the hood and the doors. Can you feel any thing? If you can, block sanding is your only cure, whether it is a small area or the whole car.
Start with a relatively coarse paper, somewhere in the neighborhood of 200-grit paper and go from there. Once sanded, some sanding scratches may still appear, and you'll want to move on to 400- and then to 600-grit paper. Of course, if you're readying a VW to take on Pebble Beach, you won't stop at 600-grit and you'll choose to block sand the entire vehicle gradually to 1000-grit paper. A note of caution is not to jump from one grit to another too quickly, as using a finer paper than needed will having you sanding a lot longer to remove larger scratches than the paper is designed for.
Now let's take a look at your work area and tools. If you're painting your car in your garage, you are probably aware of the laws in your area governing things like this, and you're probably also aware of the steps necessary to ensure a smooth, clear finish: cleanliness is next to Godliness in the paint booth realm. You'll need a well-lit environment (outside is sometimes best) and plenty of room to work around your car.
Sandpaper can be had at most of the better-stocked auto supply stores and come in a surprising wide variety of grits and sizes: 36-grit paper is like gravel compared to the smoothness of a 1200-grit sand paper. In addition to this, there is wet and dry papers, needed for two different stages of sanding. Mated to these papers are sanding blocks (or boards). This is the most important step to a great paint job, so do it right and don't rush it. Buy the paper in a roll and then tear it to length for the block or board you're using. In this form it has an adhesive back and works a lot better than sheets of sand paper. Generally, these come in three sizes, and it is a good rule of thumb to use the longest block that will fit in a certain area you're sanding. The smallest block is no bigger than your hand and works well in tight spots like quarter panels and door posts, while the largest one is approximately three times as long as works well on door panels and parts of the deck lids. Since there are very little flat parts on a Volkswagen, some auto parts stores offer curved sanding blocks for curved areas like fenders and the hood. Using your hand as a backing to the sand paper will leave small low spots thanks to the varying muscles in your hand and fingers. Sanding blocks provide even pressure the length of the whole block. Change the sandpaper as soon as it stops cutting, and don't push it or you will start digging out spots. Knock your paper often to remove sanding dust from it and wear a mask.
There are countless primers on the market for a wide variety of applications, etching primers, guide primers, sealing primers, high-build primers to name a few.
Since we're working with bare metal for the most part, we will use some self-etching primer to bond with the metal. After the primer has dried, sand the surface again with course sandpaper such as 180 grit. Most of the primer will be sanded away and sand scratches will allow the second coat primer to stick better.
Self-etching primer is a professional quality product that most body shops use to prevent metal from rusting. It's rather expensive but far superior than normal primers you find in stores. Self-etching primer is now available in cans at most NAPA parts stores and other auto parts stores. It's definitely the product to use on bare metal.
Next, wipe the paint surface down with a wax and grease remover solution which prevents future potential paint problems caused by waxes or oils which may have gotten onto the paint surface at some point. It's a good idea to do this even before you begin any repairs to the bare metal. If you don't have any wax and grease remover, you can also use a rag moistened with a spray cleaner like Windex or 409. Don't apply cleaners directly on the filler, if you're using it. They'll absorb the moisture.
Since we applied two coats of etching primer over the bare metal (same product we used earlier), then two coats of primer over that. After our primer dries, it should be block-sanded to further reduce sand scratches and high/low spots and produce a nice, smooth surface for the paint.
If you're spraying smaller areas you can achieve good results using spray can primer, but apply it in several light coats. It's a good idea to let spray can primer dry for a couple days before sanding it to allow the thinners to fully come out. Spray can primer shrinks so you want it to shrink before sanding it to minimize sandscratches from appearing after it has been painted.
One of the most important and critical steps to getting good bodywork is block sanding the primer. No matter how well your bodywork was, there are still going to be raised areas at the filler's edge. The way to produce smooth and high-quality bodywork is to blocksand the primer. Carefull sanding removes any lingering imperfections or uneveness in our bodywork.
Another good technique is to apply a "guide coat" over the primer prior to sanding. It helps produce a clean, ding-free and scratch-free surface (remember, any dings and scratches left in the primer will be clearly visible once covered with shiny new paint). You could use any color of paint or primer as long as it is contrasting in color. It allows us to 'see' the areas that need more sanding. A guide coat is simply a thin mist of paint you spray over the primer that is a contrasting color to the primer. It can be another color of primer, black paint or any other color paint you have around as long as it is significantly different in color than the primer. In our example, our primer was beige colored. We sprayed a very thin mist coat of flat black paint from a spray can over our repaired area. Don't spray it on too heavily--just a light mist will do--then let it dry. As you sand the primer, the guide coat will be sanded off first, revealing even the smallest sand scratches and low spots.
If you have sanded through the primer in many places, or the primer didn't fill the sand scratches or low spots, you may need to apply another coat of primer and sand again. Body filler absorbs water so if it gets wet, allow plenty of time to dry before priming again.
Esentially, that is the thick and the thin of it. If you've followed along, although it is incredibly tedius for the whole car, you will have a perfectly sanded, smooth, primered car, ready for the paint booth. Until next month, stay Super.
You can see the line where...
You can see the line where we stopped, about half way up the hood. Below is primer, above, scuffed original paint. Pay close attention to the line between the two. It has to be perfectly smooth and flawless, otherwise any flaws will translate through to the new paint.
The idea here is to get it...
The idea here is to get it as smooth as possible. Since we had a lot of surface rust, we took this section down to bare metal and added several coats of primer, sanding between each one.
This is the ridge that forms...
This is the ridge that forms when the original paint meets a bare-metal-primered surface. This blemish will ruin any paint job, no matter how expensive it is.
Here is a typical door, ready...
Here is a typical door, ready for sanding and priming. The best method here is to get a block sander and take your time. Use a contrasting-color primer as a guide coat to locate small imperfections as you sand.
The finished results will...
The finished results will be a perfectly smooth panel, such as this apron.
Unfortunately, sanding just...
Unfortunately, sanding just one portion of the car (like this hood) leaves blatent imperfections that will need to be tended to by using a finer and finer grit sandpaper.
If not fixed, bubbles will...
If not fixed, bubbles will transfer through any new paint you apply.