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Painting with Tamiya Synthetic Lacquers

by, Peter Johnson

The recent introduction of Tamiya's synthetic lacquers gave hobbyists a new and very important tool to create high quality glossy paint on their models. Being lacquer, it has a number of qualities that are very desirable for high gloss paint. It is hard, polishes well and dries very quickly. However, it is different from the usual enamels, and requires several different techniques. To aid the learning process, I offer a number of tips that will help avoid some of the issues you may encounter when using this product. Some of this advice is applicable to any painting situation. If you are having difficulties with other painting projects, consider using these procedures.

My first bit of advice applies to all painting projects. Every modeler should have a big sign over their work area, "PAINT HIDES NOTHING!!" Paint is not a filler. To get a good paint job, the layers should be as thin as possible so you do not bury detail. If you are trying to hide scratches and poor body work with paint, you will get a thick build up, which will hide detail and throw off the proportions. Companies, such as Tamiya, go to a lot of effort to give the modeler a highly detailed subject. Highlighting this detail requires a very thin layer of paint.

A good paint job begins with the best possible painting surface. Spend the extra time to prepare the surface so that it is as smooth and error free as possible.

PRIMING

After the surface is prepared, it needs a thin coat of quality primer. This is necessary for the paint to stick properly. All paints are essentially pigments and binders (glue if you will) dissolved in a solvent. For the paint to bind properly to the surface of the model, it must be free from oils, dust and other contaminants. Because of this, it is important to wash the model thoroughly with detergent and warm water before painting. Hot water can cause the plastic to warp, so be careful with the temperature. As an additional step, I soak the model briefly in a mild solution of automotive engine degreaser before washing it with soapy water. This ensures that the mold release agent used by the manufacturer is completely removed. As a final step, I use a spray bottle of distilled water as a rinse. These last two steps may not be necessary but the extra couple of minutes they take are far less than the time required to strip and repaint.

After the model is clean and dry, I spray a thin coat of Tamiya's gray Fine Surface Primer. This first coat does two things. Because it is a flat paint, it gives the color coats a good surface to adhere to. Paint shops refer to this as giving a surface "tooth." Second, it highlights any defects in the finish that may need to be corrected. Problems are easier to see with gray primer than white primer. If you have any defects, fix them and respray with primer. If your model is going to be painted with a light color, I suggest a second very light coat of white primer. Many colors are somewhat translucent and a dark under coat can cause the final color to change. This is particularly true of reds, yellows, and whites. A gray undercoat may change the shade and require far too many coats to get the correct final color. After priming, set the model aside to dry for at least 24 hours.

PAINTING THE COLOR COATS

This next part is where good procedure and a good eye become very important. Good procedure is necessary to prepare the paint for use and a good eye to see what is happening as the paint goes on. Understanding what happens to paint as it goes from the can to the final paint surface will help you look at the model as you are painting it and make adjustment to compensate for variations before they become problems.

The first thing that happens to paint when you depress the nozzle is that the paint is atomized. That means that it shoots out of the nozzle under pressure and becomes tiny droplets flying through the air toward the model. When they land on the surface of the model, they try to spread out and join the other droplets to form a uniform surface, just like a puddle forming in a rain shower. Ideally these droplets are very small. Smaller droplets mean a thinner, more even coat of paint.

At the same time as the droplets are trying to spread out, the solvent which keeps the paint liquid is evaporating, causing the binder to set up and stop the flowing. If the solvent evaporates too soon, the surface doesn't have time to get perfectly level and you get the dreaded "orange peel" effect. In extreme cases the solvent evaporates too much en route to the surface and the paint remains in the form of little spheres which stick to the surface. This causes the surface to look like flat paint.

Having said this, you may well ask, "So what? I'm using a spray can. I can't thin the paint because it is premixed in the can, and the pressure is determined by the manufacturer of the can." This is only partially true and there are several variables that you can control. For example, you can control the distance from the nozzle to the model, the temperature of the paint, and the speed you move the can across the model. Here is how to use them in your favor.

First, always heat the can in medium hot water before you use it. Always read the label to be sure you don't get it too hot. If you over heat the can, it could explode and instantly paint the room instead of the model. Not the desired effect! Personally, I made a trip to the kitchen and stole the food dehydrator to heat my paints. If you do this, be sure to check the maximum temperature of your unit, to make sure it will not overheat the cans. Heating the paint does two things. First, it reduces the viscosity(thins) of the paint and helps it to flow better. Second, it significantly increases the pressure in the can which helps atomize the paint to finer droplets. A side effect of the increased temperature is that the solvent evaporates faster, so be aware of this and be prepared to move the can closer and move it faster to compensate for the increased flow of paint.

Once the can is heated, the paint needs to be mixed. Like any paint, the pigments in a spray can tend to settle to the bottom and need to be re-mixed with the binders. To most people, this means shake the can. Unlike James Bond's perfect martini, paint should be stirred and not shaken. With the demise of CFC's as propellents for aerosol cans, the gasses used as propellents in spray cans tend to dissolve in the paint. When the paint is sprayed, the gasses can come out of solution and form bubbles in the surface of the paint. With slow drying paints, such as enamels, this is not a problem because the gases have time to escape from the paint before a skin (flash) forms on the paint. With fast drying paints like lacquers, a bubble will form under the dried surface and create little pinhole like imperfections in the paint. This often happens in areas where the paint is thicker, such as in panel lines. Gasses under pressure, such as in a spray can, naturally dissolve in the paint while it sits on the shelf. This can cause enough potential problems, but additional gas bubbles can be added by shaking the can. The can should be held at the top and swirl the bottom, so you can hear the ball bearing running around the bottom of the can. Heating the paint also tends to reduce this problem.

Ok, so we have the model prepared, the paint is heated and mixed and here we stand with our heart in our throat, about to put some color on the plastic. Just hose it down, right? Well, not exactly. When spraying, never start or stop the spray over the surface of the model. Start the spray to one side, spray over the model in a smooth straight line, and stop the spray after the paint stream has passed the end of the model. This prevents any drips which may build up on the nozzle from hitting the model in a big blob.

Next we need to train our eyes on how to look at the paint. When inexperienced painters spray, they tend to look at where the paint is going and don't actually look at the surface of the paint to see what it is doing. They look at the surface after they are done and wonder what happened. The best analogy I can give is looking at a pond of water. If the surface of a pond is smooth, most people will focus on the bottom of the pond and see only what is on the bottom of the pond (the opaque pigments of the paint). They do not see the surface of the pond (the clear binders) unless the surface is rough. Learning to focus on the surface takes practice, but by training the eye you can see what is happening as the paint goes on the surface. Is it going on too dry or too thick? Is it drying too fast and leaving orange peel? Are there bubbles in the surface? These are all things we can correct by adjusting the way we spray.

To adjust the drying of the paint, the distance between the model and the nozzle can be changed. A large amount of solvent evaporates while the paint is traveling through the air from the nozzle to the model. The greater the distance, the less solvent in the paint when it hits the surface. If the paint is flat on the surface or is leaving orange peel, move the spray can closer to the model. If you do this, you will need to move across the model faster. A small adjustment in distance dramatically changes the size for the spray area. In preparation for this article I measure the changes that occur when you move the can closer. The typical Tamiya can has a spray pattern which decreased the area covered by 40% when it is moved from 7 inches to 6 inches. That means that if you move at the same speed and move 1 inch closer to your model, you almost double the amount of paint applied. If you move closer to keep the paint flowing, you need to move across the model much faster. Remember we are trying to lay down a series of thin coats.

Allowing the paint to dry between coats is also important. If the paint does not have enough time for the solvents to evaporate(off gas) between coats, the paint will remain soft longer. It may also crack weeks or even months after the final coat of paint. If you spray on a very thin coat, let it sit for an hour, then spray another equally thin coat, more solvent will off gas in that hour, than if you spray a coat that is twice as thick and let it sit for 24 hours. In this case, less is definitely better. For the first several layers, some painters prefer to lay down several mist coats (sprayed from a distance, so the paint is almost dry when it reaches the surface). This is generally done in the belief that it prevents the solvents from melting(crazing) the plastic. I generally use this technique if I have done extensive body work and have several dissimilar types of plastic or filler that I am painting. A good quality primer should do the same job.

Another issue for novice painters, is that they expect the color coats to cover to a final shade on the first coat. If you follow the proper procedures, and build up several coats, you will not get opaque coverage with one or two coats. Be patient. Learn to look at the surface of the paint to see that you are getting an even, smooth surface. Remember, coverage will happen with a build up of layers. Concentrate on what is happening to the surface.

If you notice defects, such as dust or orange peel, take care of the problem before your next coat. Don't just keep spraying, and hope to cover up the problem up with more paint. Remember, "PAINT HIDES NOTHING." Careful wet sanding between coats is a good idea for correcting problems. This adds tooth to the colored surface. While this is more important for enamels than lacquers, keeping the surface smooth between coats is a good idea for all paints. If you need to do major sanding, let the paint sit for 24 hours before sanding. Otherwise, you will load the sandpaper up with the partially dry paint. For dust or other debris, a quick wet sanding with a light grit (2,000 to 3,000 grit) wet/dry sand paper is a good quick fix. As a personal preference, I use distilled water as a wetting agent. That way, I am sure that I am not contaminating the surface with minerals or other chemicals which may be present in tap water.

If you have orange peel, use a sanding stick to level the surface first, then take out the scratches left by the sanding stick with light grit sand paper. Sanding sticks are available, in a number of grits, at any well stocked hobby shop, or in the fingernail polish section of most drug, grocery, or department stores.

POLISH OR CLEAR COAT

Once you have the opaque paint built up to the desired level, you need to decide if you are going to polish the finish as is or put a clear coat over the top. Clear coating is most desirable if you have decals that need to be protected such as on racing cars or cars with graphic exteriors such as police or delivery vehicles.

If you decide to clear coat, keep in mind that if opaque paint hides nothing, then clear paint really hides nothing. For that reason, before you clear coat, the opaque paint underneath needs to be as smooth as possible. The best way to think of clear coat is like a piece of glass. If the glass is over a piece of sandpaper, the gloss will not look as deep as if you place it over a piece of highly polished metal. Light reflection is what show stopping finishes are all about.

Since finish polishing and sanding is the same for clear and opaque paints, lets move on to that subject now.

POLISHING PAINT

First of all, lets start by saying that finish sanding and polishing paint is a matter of personal preference. If you are building a model for shelf display or a desk, then Tamiya lacquers, straight out of the can, may give you an acceptable finish without polishing. A light coat of wax, to protect the surface, may be all that is needed. Tamiya lacquers attain a very high gloss shine and a smooth finish with the procedures given up to this point. However, there are a number of perfectionists that insist on a finish over and above what comes out of the can. If you seek a competition quality finish, then lacquer can be polished to achieve the ultimate shine.

Polishing paint is an effort to make the surface of the paint as level as possible. "Deep competition paint jobs" come from an even surface, reflecting as much light as possible in a uniform direction without interruption. Polishing paint begins with a fine to very fine polishing stick. Polishing sticks are rigid and do not conform to the surface of the paint. As they pass over an uneven surface, they will contact the high spots only and not touch the low spots. With your first pass, you will see what areas need work because you will see all the high spots as dull areas. It will also highlight any dust or lint that may have gotten in the paint. Careful use of the sanding stick will produce a level surface. Use extreme care when working around sharp edges and raised detail. Lacquer tends to pull back from sharp edges and will be thinnest in these areas. Often when I am doing the initial sanding, I will put a thin piece of masking tape along the edge, masking off about 1/32" to keep me from sanding through the paint at the edge. Any unevenness in that area will not be obvious once the model is done.

After you have the paint leveled out, you need to remove the fine scratches left by the sanding stick. Starting with a 3000-grit wet/dry sanding cloth, work your way through several grits of progressively finer sanding cloth until you reach an 8,000 to 12,000 grit. If I am going to clear coat over opaque paint I stop at 8,000 grit. If this is my final opaque or clear coat I will go all the way to 12,000 grit. I use distilled water as a wetting agent for all of my sanding because it does not leave any dissolved mineral behind to be worked into the paint surface. This is helpful if I have to go back and touch up any areas I have sanded through.

Once you have finished with the 12,000 grit the paint should have a nice gloss to it. In many cases this is good enough, but for that ultimate shine, use a soft cloth(I like an old T-shirt) and Tamiya rubbing/polishing compound. Put a little polishing compound on the paint and rub it in a circular motion with the cloth using light to moderate pressure, covering a small area at a time. This will take out the ultra fine scratches left by the 12,000 grit. I like to use the Tamiya polish because it appears to have no silicone in it. If I need to touch up the paint for some reason, I do not get excess surface contaminations that may cause fisheyes in the paint like other polishes. After you have finished polishing the surface, a light coat of wax, such as Tamiya modeling wax, gives the finish a very high luster.

If you practice these techniques and improve your eye for finishes, you can take your modeling to a higher level. The key is practice. Try some of these approaches on an old scrap model and adapt them to your preferences. One final thought: When I first started painting for competition, a good friend and painting mentor told me to keep a log every time I painted. In that log I record the paint I used, the temperature and humidity, and any special techniques. I noted what worked and more importantly, what didn't work. I still use that book every time I pick up paint. Develop a system that works for you, and good luck.

Problem	Cause	Fix	Solution	Tips
Orange Peel	Paint is drying before it has a chance to level.	Sand with a sanding stick to level the surface and repaint.	1) Heat the paint. 2) Move the can closer to the subject.	If you heat the paint or move closer the amount of paint you apply will increase. You will need to move accross the subject faster.
Flat or dull gloss	Paint is drying too much before it hits the surface of the subject.	A light wet sanding and repaint.	Move the can closer to the subject.	See above.
Sags or runs	Paint is thick or drying too slowly.	Sand with a sanding stick to level the surface and repaint.	1) Heat the paint. 2) Move the can farther from the subject. 3) Move across the surface faster.	Most often you have applied too much paint. It is easier to add paint than to remove it.
Fisheyes (dimples in the surface)	Surface contamination	Wet sand the area down to primer and repaint.	Carefully wash the surface before you paint.	Painting is all about clean, flat surfaces.
Blobs of paint	Dirty nozzle or old paint.	Sand with a sanding stick to level the surface and repaint.	Clean the paint can after each use. Hold it upside down and spray until only the propellent comes out. Then clean the nozzle with a cotton swab dipped in lacquer thinner.	If you will be reusing the can within an hour or so, blowing is nessesary. Clean with a cotton swab. That will save your paint and propellent.