To execute a simple, but elegant color scheme, of say four colors, it may take five colors to do the job right. For example, it is often desirable to have a separating color between each of the major colors. This sometimes is done with tape, but a more professional job is done with paint.

Let us assume that we are planning a color scheme using the cool side of the color spectrum. This might be medium blue, light blue, lavender and rose (mauve). Regardless of the specific design layout, it would be desirable to separate these colors from each other with a different color. My choice would be silver, rather than a darker color such as black or red, but this is a matter of personal taste.

The technique would be to paint the whole coach with the silver color. Then the graphics would be laid-out using a fine line tape, for example, one-half inch wide. Then the various colors would be painted and masked between. After the last color has been applied, the fine line tape would be stripped, leaving a silver margin, or separator, between each color. After that, a the clear glossy coat is applied over the coach. When the clear coat is completed, the separator lines almost look like tape, but they do not protrude above the surface contour as tape would.

3M manufacturers a variety of vinyl tapes in many colors and widths that are used for graphic design. Although the tape lays on the surface, it is quite thin and a skilled applier can make it look like a high-level paint job. This material is applied with water. What this means is that the surface of the bus must be smooth, and with its final finished color completed. Then, kept wet while the graphic tape is applied. This allows the tape to be adjusted, straightened, and aligned before it sets up on the surface. After the tape is in position, it may be sponged to remove excess water and then squeegeed to bring it down to the surface. The advantage of this system is minimal masking with the edges of the graphics being sharp and precise. The tape process may also be used as separator lines between colors as we discussed in the preceding paragraph. One advantage of doing it this way is that by using the graphics tape as a separator color, the masking between colors does not have to be as precise.

Another technique for doing graphics color separation is to build colors on top of colors. In this approach, we use our spray gun and spray a color along a stripe without any masking, making sure that we have sprayed over the area belonging to that color, and allowing it to fade out on each side of the target area. That stripe, or section, is then carefully masked with fine line tape and paper. Then we spray the next adjacent color, again without masking, and allowing it to fade to each side. The new section is then carefully masked, and we continue to apply as many colors as we wish using this technique. It is important when using this technique, to make sure that the masking tape does not lift the newly applied paint. This can be assured by following the manufacturer's recommendations. With most urethane based base coats, they may be taped over in about thirty minutes after application without being lifted by subsequent masking.

This brings us to the various paint systems for automotive painting. Almost all the new cars built today use a urethane paint system, sometimes called a polyurethane process. The older more common automotive paints are acrylic enamels, which may, or may not be catalyzed.

The modern urethane systems are applied in a two step process called a base coat - clear coat system. The base coat, is the color(s) coat, which is then covered with a clear system which adds depth and gloss. The base coat colors are a rather dull finish, or a semi-gloss finish, and with the proper reducer, will dry to touch in about five to ten minutes. The reducer must be selected according to the temperature of the part being painted. Obviously, if you have to paint outside in bright sunlight, you may not be able to find a reducer that will work, because the surface temperature of the coach may be over 100 degrees. A bus should be painted inside a barn, a shelter or a paint booth, if possible. This will minimize the effect of the outside environment with its airborne particles, even on a calm day. After a base coat is applied, most systems will permit masking over in about thirty minutes without the tape lifting the paint. The instructions are given on each can of paint; follow them carefully.

In order to achieve a chemical bond between the base coat and the clear glossy coat, the clear coat should be applied within about 24 hours of the base coat application. The base coat will not have cured sufficiently, so that a chemical cross-linking will occur between the catalyzed clear coat and the base. This is a real problem with a very complicated graphics design, unless you have a team of talented personnel masking and painting.

A solution to this problem, if you are limited with personnel, ie., having the paint job done by only one person, is to take your time doing the base coat, assuring a perfect job. This may take days, or even weeks. Then, before applying the clear coat, scuff the entire coach with red Scotchbright, a plastic substitute for a scouring pad. This is somewhat like giving the coach a very fine sanding over the base coat. By doing this, a mechanical bond will be achieved, rather than a chemical bond. Will the mechanical bond be as good as the chemical bond? Probably not, but urethane has exceptional adhesive properties. Our personal coach was painted with this process six years ago, and we are still getting compliments on its new look, when I remember to wash it.

Now we must discuss a danger inherent in urethane systems. The curing agent in all urethane systems, whether they are a foam, a rubber or a coating system, is isocyanate. What is isocyanate? Isocyanate is the catalyst that allows the urethane resin to harden, or cure. In the process of use, cyanide gas is given off. The State of California uses this gas to execute convicted killers. A few years ago, Monsanto Chemical allowed, through an accident, a form of isocyanate to escape into the surrounding community of Bohpol, India, killing many people. A brief whiff of this chemical can cause permanent damage to your lungs, such as emphysema or other respiratory problems. A simple dust mask is totally inadequate to protect against this deadly gas. A filtered respirator system is necessary with plenty of ventilation when spraying a catalyzed paint. If you can have your coach painted inside a barn or other shelter, rent or somehow borrow enough exhaust fans to have an air change every few minutes. Your paint supplier has one-time-use disposable masks with charcoal filters to be used when applying this material.

If you plan to do your own painting, purchase a top loading paint gun. The inexpensive imported copies are very serviceable for a few-times usage, and are less than $100. The beauty of the top loading spray guns is that they have a built-in pressure regulator and can apply paint at as little as 10 psi air pressure. These types of guns have become mandatory in many areas concerned with air pollution, since over-spray is kept to a minimum. The professional painters, of course, pay a lot more for their equipment, since it must remain serviceable, for job after job.

How much should the materials cost to paint a bus? This may be generalized at approximately $1,000 to $1,500. The real answer depends on the level of complexity of your graphics, the number of colors, and the selection of colors. For example, deep reds require much more pigment, thus costing more than, say, mauve. When determining the material cost to paint a bus, all the materials must be included, such as sand paper, body filler, masking paper and tape, primer, reducer, thinner, color coat, clear coat, and catalyst. It is not uncommon to have the material cost exceed $2,500.

Most color coats will yield one and a half gallons per gallon, since the reducer is often mixed on a one-half to one basis. The clear coat should yield about two and a half gallons per gallon, since the catalyst is normally mixed on a one-to-one basis, and the reducer mixed one-half to one. How about coverage? An average forty foot bus, with the windows masked, and the lower section with bright metal not to be painted, will need about two gallons of material for each coat.

One of the advantages of this type of system is that invariably scratches will appear, as if by magic, from trees and shrubbery and other sources. But they may be buffed out if they do not penetrate the clear coat. It is easy for anyone unfamiliar with the technique to buff through the paint without even half trying. So take it easy! The repair may be done with 1500 or 2000 grit wet/dry sandpaper, then a fine polishing compound such as Microfinish, and finally, using a 3M product with the trade name Finesse. Use a somewhat slow polishing bonnet, so as not to overheat the surface, and it can look new in no time.