tech talk
blended area, then it needs more sanding (some sanding tips will be addressed in the next section on paint). Pieces that will be covered in suede or vinyl will typically require more planning before construc- tion than other forms of finishing. Both carpet and paint can be used to cover almost anything. Carpet can be seamed almost invisibly, and paint will cover any surface. But suede and vinyl are two materials that have limitations to what they are capable of covering. Unless you are fortunate enough to have a sewing machine, or are going to subcontract the upholstery to an upholstery shop, some preplanning can save many headaches. If I know a shape is going to be too com- plicated to cover, I will find the bad areas and work in an additional trim piece that will attach separately, allowing a clean look. Sometimes that piece will be noth- ing more than a thin fiberglass or low temp plastic piece that has been molded into the area. When all your pieces are ready to be covered it is important to go over the entire piece with 80 grit
58 Mobile Electronics June 2014
sandpaper. Keep in mind it is possible to smooth a piece out too much and reduce the ability of the glue to grip the surface. With the surface prepped, it is time to cover. There are many ways to cover a piece; I will share with you what I have found works for me. Using suede, the biggest trick I have found is to separate the suede from the backing if the piece will be difficult to cover. Care must be taken so as not to soak the glue through the material. For vinyl, only in extreme cases will I separate the vinyl from the backing. The first step in the upholstery process is to rough-cut the material and lay it, and the piece to be covered, on a smooth, clean surface. Clean is very important. Nothing is worse than get- ting halfway through a job and realizing you have a particle of debris underneath the material on the piece you are cover- ing. The glue we use is Weldwood HHR Landau top glue. It is the best glue avail- able. Before glue is sprayed, take a look at the pieces that are about to be uphol- stered. Are any of them going to need to be painted (black or otherwise) on the backside once they are upholstered? One thing that sets apart an installation is not only the visible level of finish, but also the behind the scenes finish work. I try to make sure the backsides of my panels are finished, whether with a quick coat of spray paint or upholstery. If you are going to paint, make sure to mask off the area to be painted. That will keep the glue off it and give it a nicer, finished look when painted. Once the backsides are addressed, the front side upholstery can begin. First, I spray both pieces with a light coat and let it dry for a few min- utes. Then I come back with two more light coats so both surfaces are covered with glue. I then let the glue sit until it is dry. I normally give it about 20 minutes. It is important to assess your piece before you start sticking the upholstery on. If I know I have a challenging spot, I will stick to that part first and work my way out. If the piece is large, I will use a clean piece of cardboard between the mate- rial and the piece to keep the other parts from sticking before I am ready to work with them. If the vinyl is cold or stiff, you can use moderate heat from a heat gun
to help it form easier. It is best to keep a wet towel on hand to cool the vinyl down after heating. If there are seams or corners that need to be upholstered, the corner of a right angle pick tool works well to get into tight spaces.
Paint For the paint segment I asked Randy
Swartz of Soundwaves in Tampa, Florida, to give us some insight on things he has learned over the years. Here is the infor- mation he had to share: The most versatile primer, which should be used often, is polyester high-build primer such as Slick Sand from Evercoat. The main advantage to this primer is its ability to fill in deep scratches and imperfections in the part. Sanding can be done up to 80 grit before applying poly primer. The primer will fill 80 grit scratches with ease. High-fill primer is available in a spray can, but it is best if shot from a gun. Either prod- uct should be shaken thoroughly before use in a paint shaker. Poly primer can be sprayed on in thick coats but make sure adequate flash time is given between coats. The amount of time you should wait before sanding is usually listed on the can. Four to six hours is best in most cases. Once cured, the primer can be sanded and even shaped. A second application of poly primer can be used if needed. There are a few reasons you may need a second application. For example, if there are several burn-through areas in the primer or if more build-up is needed to help shape the part, a second applica- tion may be required. Poly primer also works very well overtop MDF. Polyester primer is a catalyzed primer, so it should only be mixed right before it is time to spray. The gun should be taken apart and cleaned out using a wash-grade thinner as soon as spraying is complete. Catalyzed primer will ruin the paint gun if it isn’t cleaned out right away.
Sanding Tips ALWAYS use a sanding pad. Bare hand sanding can cause ripples in the part. These ripples will show up after the part has been painted, especially if painted with base coat or clear coat. A medium
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