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Easy Finishing Techniques


Easy Finishing Techniques

How the Weather Affects Paint Drying Time

Throughout this manual, youíve read how you should wait a number of hours for paint to dry. Most gloss finish paints take 12 to 24 hours to dry completely; flat finish pints take about half this time. Testor enamels take 24 hours to dry completely (both gloss and flat). Generally, lacquers dry much more quickly, usually within 1 hour, depending on the type of lacquer, thickness of coat, and whether the lacquer is applied with a spray or brush. Testor putty should be allowed to dry for at least 24 hours before any wet or dry sanding is done.

As you may have guessed, the weather partially determines how long paint, lacquer, or putty take to dry. In a warm, dry climate, drying time is very quick. But decrease the temperature or increase the humidity (the amount of moisture in the air), and drying time increases.

The average drying times for Testor paints, lacquers, putties and cements are affected by changes in temperature and humidity, especially for paints. For example, you should wait another 12 hours paint to dry if the humidity is above 50 percent and 24 more hours if it is above 80 percent. You can find out the humidity with a dial hygrometer (which is like a thermometer, only it registers moisture content in the air), or by checking the daily newspaper.

Some weather just isnít well suited for model building, but that doesnít mean you have to give up your hobby just because itís raining outside. You can help speed up the drying process with the use of hair blow dryer. Set the dryer on low or no heat and point it at the model. Keep the nozzle of the dryer at least six inches way from the model.

Turn on the switch and let the rush of air speed-dry the paint. Remember to use as little heat as possible, or you may ruin the model. Keep the dryer moving at all times so that the paint dries evenly. This technique is not recommended for high-gloss finishes (auto bodies).


Applying Protective Overcoats

In the model building using cement section, you learned how to spread a thin layer of kitchen floor wax over the model. The wax adds a touch of brilliance to the finished kit and also helps protect its surface. A protective overcoat is especially important when you have painted the model or applied decals.

Testor Dullcote and Glosscote lacquers are the most common and long-lasting forms of overcoats. The easiest method to apply these is by spraying. Use Glosscote on models that should have a shiny finish (such as cars); Dullcote on everything else (especially military aircraft).

You may need to apply several coats to cover the model adequately. If you apply too thick a coat, the lacquer will pool up in one area and look unsightly. After it has dried completely, use extra-fine steel wool to buff away the extra lacquer. Do the same for any bubbles you see in the finish. Respray a thin coat and let the mode dry for at least 24 hours before handling it.


Primer Painting

In the last chapter, you learned about applying a coat of primer to the model before the actual painting. The primer step is not always necessary, but it helps your models have a smoother, more refined look. The primer also helps seal any putty you have applied to the model and locks out moisture. Youíll especially need the primer if you are painting the model with a metallic or metal flake paint. These paints use transparent pigments, so the color of the model can show through the final coat of paint.

There are a variety of primers you can use, as well as a number of paints you can use as a primer. Real primer is called chromate or zinc chromate, and has a slightly green tint. This kind of paint does the best job at priming the model for subsequent painting. It is available from Testor in both bottle and spray form, and it has a flat finish.

You can also use Glosscote or Dullcote as the underpaint primer. Both Glosscote and Dullcote are lacquers, but they can be successfully applied under Testor enamel paint (usually, you donít want to mix lacquers and enamels). It comes in bottles and spray cans.

Neutral color paints can also be used primers. White is a good choice if the final color is very light, like yellow. Rust, tan, and gray are also good choices because they do a good job of covering the plastic of the model, but they arenít so dark that they affect the finish paint. Obviously, you would not want to use black as a primer because it would show through almost any color.

You can use either gloss or flat finish paint, but flat is probably the best all-around choice. Flat paint dries faster than gloss paint, and the rough finish helps the finish paint adhere better. If you want a really smooth final paint job, however, you should buff the primer with fine steel wool (000 or 0000)* before applying the paint. Be sure to remove the paint dust before applying the finish coat, or bits of dried primer will show up on the finished model. Feel free to use steel wool between successive coats of the finish paint. That helps smooth out the final paint job, too.

*Steel wool that has been treated with oil is not suitable for this. Use only dry steel wool.


Thinning Putty

Some cracks and crevices are too narrow to accept the full-bodied putty as it comes out of the tube. Thin the putty by mixing it with a small amount of paint thinner. Squeeze some putty onto the paper and add a drop or two of thinner. Mix it with the ice cream stick or toothpick. Keep adding paint thinner until the putty is the consistency you want. The putty should not be too thin or it will run down the sides of the model when you apply it. Thinned putty takes longer to dry than non-thinned putty, so allow extra time before you sand and paint. You can store thinned putty for later use in a paint jar thatís been thoroughly cleaned out.


Testing and Sealing the Putty

You really canít test how well you applied the putty until the model is painted. Once painted, you can see how the putty blends with the rest of the model. But you may not want to paint the entire model yet, so the next best thing is to apply a thin coat of gray or primer paint only to the puttied areas. You can spray or brush the paint onto the model. After the paint is dry, if you spot any roughness in the putty job, sand the paint away and smooth out the putty even more. Keep at it and youíll end up with a superb job where the seams between the parts will all but disappear completely.


Sanding Putty

Once the putty is dry, it can be sanded and painted. Sanding is best accomplished with fine grit wet/dry sandpaper, used wet. If you have applied too much putty or havenít smoothed it out enough, you may want use coarser paper or a small jewelerís file to get rid of the excess build-up. Do the final finishing with the fine grit sandpaper.

You will notice that model putty shrinks a tiny bit as it dries. As you gain experience with applying putty, you will know how much extra to put on so that when the putty shrinks, the hole or gap will be properly filled. If in doubt, apply the putty in layers, especially if the area to fill is large. The last layer should fill in any small areas left over from shrinkage.

You can test the smoothness of our sanding job by running your finger over the dry putty. Can you feel any hills and valleys? If so, keep sanding. If you sand off too much, you can always apply more putty and start over again.

Now that you have practiced applying putty on discarded parts, itís time for the real thing.


Applying Model Putty

You can apply model putty with the blade of a screwdriver, a toothpick, or better yet, with an artistís palette knife. You must work fairly fast because the putty starts drying quickly.

Practice applying putty on a scrap piece of the model. As you build more models, youíll quickly learn to keep all parts you donít use; the extras may come in handy some day.

Squeeze a small portion of putty onto a piece of paper. Donít use a paper towel because the lint will mix with the putty. Putty has a solvent base, so it can soak through the paper. Protect the table with a drop cloth and art board, as usual. Dip the palette knife into the putty and apply it on the part. Donít worry too much about neatness now.

Practice smoothing the putty along the length of the part. Use the palette knife. Try to get an even amount on the entire part. High spots will have to be sanded down, and that makes more work for you. Low spots will have to be refilled to make them even with the rest of the putty. If the putty starts to set up before it is smooth, dip a cotton swab in a bottle of paint thinner and rewet the putty. Donít apply too much thinner or the putty may run. The layer of putty shouldnít be thicker than the thickness of your fingernail. Drying will take much longer if the layer of putty is extra thick.

Model putty takes about 24 hours to dry, so set the piece aside overnight. Work on the rest of the model to pass the time. Remember: Donít try to sand or paint the putty until it is thoroughly dry.


What is Model Putty?

Model putty comes in tubes and squeezes out just like cement. Out of the tube, model putty is fairly thick, about like toothpaste. You can apply the putty as is, or you can thin it with paint thinner. More about this in a bit.

Model putty is specially engineered to be used on plastic kits. It sticks to the plastic and wonít harm it. You should never use wood putty or other filler not designed for plastics. The putty may harm the plastic parts or may not dry to a smooth finish.


Filling and Smoothing

Sometimes the parts of your kit may be damaged as they are removed from the runner, or they may not fit together exactly. There may be holes or unsightly gaps in the model, and no matter how nice the final paint job, your kit will look unprofessional.

Fortunately, all is not lost. You can use a special modeling putty to fill in the mistakes. One the putty is dry, it can be sanded an painted over. If you do the job right, no one will ever know that youíve applied putty to your model. As you become more experienced in model building, youíll use putty all the time to fill seams in joints and to make the surface of the model look smooth and unbroken.


Finishing

Finishing is what you do to make your models look more professional and realistic. Youíve already done some finishing--applying decals, spraying and brushing on paint, even waxing your models with floor polish so they shine. If youíve followed directions and taken your time, your models should start to look pretty good.

Now youíre at that point, however, when you want your models to look even better. You want to smooth out the mold marks in the seams of your models; you want to spray primer coats so that paint job looks smooth and professional; and you want to apply finish coats for a long-lasting and protected paint job. Keep reading and find out how you can master these and other finishing techniques.