Painting is a great and very important part of any model aircraft building project. A well-done paint job will immediately draw attention to your plastic model aircraft and give it a sense of realism.
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To create a decent model, you must paint every single little part correctly and with great care. The main rule is that the only parts to leave unpainted are the clear parts, such as windows and windscreens.
Always use paint specially designed for plastic models. There are many other kinds of paint, such as car paint, but most of them will react poorly with plastic materials – they might for instance melt or “eat” the surface of the plastic and thereby ruin your model.
There are lots of different brands of model paints, such as Humbrol, Tamiya, Xtracolour, AeroMaster or Gunze Sangyo. But it all breaks down into basically two different kinds of paint: enamel paints and acrylic paints. Enamels are mineral spirit based, and acrylics are waterbased.
Both types have their benefits, but if compared, I believe that acrylic paints are the clear winners. They are non-toxic and cleaning up is a breeze – you just use regular tap water to clean your brushes and painting tools. They are fast drying, easy to thin with distilled water, and have the same silky smooth finish as enamels. Even though they are water-based, they are totally waterproof when dry.
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How to Paint Plastic Model Aircraft – Everything You Wanted to Know.
Table of Contents
- The Basics
- Advanced model painting techniques
- Finding the Right Colours
- Bare metal
- Using Acrylics
- Paint Additives and Thinner
- Polishing a Finish
- Clear Coats
- Alclad II and Model Master metallizer
- Metal Foil
- * Once again, a clear coat isn’t necessary. It will alter the appearance of the foil.
- Best Books about Painting Model Aircraft
- Building Plastic Model Aircraft Kits
Paints can be either glossy or flat. Cars are almost always shiny and glossy unless they are very dirty. But most military vehicles have a rather flat finish to avoid being easily spotted by the bad guys. This is the surface you should be attempting to achieve.
Professional model paints are most often bottled in small, unbreakable glass jars with a printed label stating the name and number of the colour. There are many different colour numbering systems around, but if you just use the name as a reference – for instance, “Light Ghost Grey“, you will seldom go wrong.
Open the jar with your fingers or a jar opener. If the lid of the bottle won’t come off, you can use a pair of adjustable plumber’s pliers. Be careful not to deform the lid, or you may not be able to tighten it back when you’re finished painting.
A paint consists normally of two ingredients: a solvent and the pigment. The solvent is the thinner or the “fluid” in the paint. The pigment consists of the colour particles floating in the solvent. The pigment is usually heavier than the solvent, which means that it will sink to the bottom of the paint jar. Before you can use the paint, you must, therefore, stir the jar well.
Shaking the bottle is not recommended because it will not mix the paint and might create air bubbles in the paint, which will make it more difficult to obtain an even paint surface. Use a toothpick or an ice-cream stick to really mix the paint with the solvent. Use a separate toothpick for every colour, or you will be mixing the colours. Make sure that you reach all the way to the bottom of the jar!
Model paint is unfortunately very expensive, but usually, you will have some paint left in the jars when you have finished a model. After a while, you will have amounted a nice collection of paints. Keep the bottles in a shoebox or a toolbox, so you can find the one you need later. A good tip is to store the bottles upside down. This way the solvent will not evaporate so easily even if the paint is stored for a long time. Also, keep empty paint bottles – they may come very handy when mixing or thinning paints.
I always write a descriptive text on a piece of masking tape and attach this to the jar. A description like “Light gull grey, airbrush-thinned” will help me find the exact colour I will need on the next model building project.
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It should also be mentioned that there are two groups of paint that are slightly different: varnishes and metalizers.
A varnish is a clear (colourless) paint. These are used to “seal” the underlying paint surfaces along with the decals, and also to change the glossiness, or sheen of the model There are various degrees of shiny varnishes, from high gloss varnishes to completely flat or dull varnishes.
Metallic paints are actually colourless paints mixed with microscopic metal particles. When painted on top of a coloured surface, they will give this surface a metallic sheen. We will look into metallic paints in a minute!
There are a few very important points to remember when painting a model. First of all, make sure that your surfaces are completely free from dust and grease. The plastic parts are usually quite oily from the moulding process. It is this oil that helps to separate the moulded plastic parts from the metal mould in the factory. This “mould grease” must be washed off, or the paint will adhere badly or not at all to the parts. This is most easily done by first washing the whole plastic trees in tepid water with some dish-washing detergent. Be careful not to break off and lose small parts while doing so.
After the main assembly, when it’s time for the main paintwork, wash the model a second time and let it dry for a day or two. This second washing is essential for removing handling grease from your fingers and dust. It may feel strange to wash a model aircraft the same way as a plate or drinking glass, but don’t be afraid – it will not melt unless the water is hot.
Base coating (or priming) is essential to achieve a good paintwork. It is most often necessary to find imperfections, bad seams, and rough areas that need more sanding. Also, when painting a model in a similar colour as the colour of the plastic, it may be advisable to first prime the model in a different colour. This makes it easier to find spots you may have missed painting.
There are special priming paints (such as Mr Surfacer) that are better at hiding minor scratches and surface imperfections, but you can also use a normal light grey or white enamel paint as a primer. Use a light colour (light grey or white) or you will have much harder to get the final paint to cover the primer layer.
I would recommend that you use an enamel based primer, as these tend to stick to bare plastic a lot better than water-based paints.
When the primer layer has fully dried (after at least 24 hours), you should gently sand the paint with a very fine grit sandpaper. I usually use a worn 1200 grit wet-and-dry sandpaper to carefully sand or rub the paint. I use a lot of water so that the tiny sanding particles won’t scratch through the paint layer. Rubbing the primer gets rid off all the minor lumps and bumps that may be present on the surface, and it also makes a lot better base for the final paintwork.
Beginners almost always start with brush-painting their models, before moving on to airbrushes. We will cover airbrushes in the next chapter, but for now, we will focus on paintbrush techniques.
Before reaching for that brush, stir the paint well at least for one minute. Make sure that the paint has the right consistency – for brush painting it should be somewhat thicker than milk. Use an eyedropper, or a piece of straw to transfer the thinner into the paint. Only add a small amount of thinner at a time, because it is always more easy to thin the paint than to thicken it. Be sure to mix the paint even after the thinning.
Buy decent artist’s paintbrushes and not those cheap ‘n’ crappy paintbrushes we’ve all been messing with as kids. I guarantee that it will be worth the investment in the long run!
Never immerse the bristles of the paintbrush more than halfway into the paint, or you will get a sloppy result and will also ruin the brush. Even if you only wet the tip of the brush, the paint will be transferred all the way into the brush, by an effect called “capillary action”.
Small parts can often be painted directly on the runner before being cut off. Don’t forget to touch up the parts after detaching them.
When using a paintbrush for larger areas, try to move the brush in only one direction; if your paint has the right consistency, the brush strokes will disappear as the paint dries. Don’t paint back and forth, or you will end up with ugly and visible brush marks.
Don’t try to cover the surfaces with one heavy layer of paint, but paint several thin layers, letting the paint dry overnight between each application. Trust me – your patience will be rewarded later! For some colours, like white or yellow, you may have to paint as many as five or six layers before you have a solid, opaque film. If the paint appears to be covering after only one application, it is way too thick! It will not dry properly, it will cover up the fine details and it will leave bristle-marks on the model.
Small details may, of course, be painted with thicker paint straight out of the bottle. The brush marks will not be visible on the small details anyway and you really don’t want the painting to take ages! When painting small areas, it’s important not to overload the brush, or the paint will run immediately as the brush comes in contact with the part and cover all the details. Also, make sure that the paint does not dry in the brush, or you will find it very hard to paint precise shapes. If it happens, wash out the brush and thin your paint a little.
Large areas as very difficult to paint evenly using a brush. Try to paint light colours first and work towards the darker colours, leaving enough time for the paint to dry – usually 24 hours for most enamels and at least a few hours for acrylics. If you try to paint another layer too soon, you risk melting the previous layer and making the paints to run into each other with a real messy result.
When you are finished with the painting, make sure to clean the brushes with thinner if you are using enamels, or with water if you are using acrylics. Don’t let the paint dry in the brush, or it will be ruined. When the brush is clean, wash it out with some water, and set it to dry in a jar. Don’t ever let the brush rest on its bristles, or they will bend and the brush will become unusable.
Advanced model painting techniques
Using an airbrush
Almost all beginners decide to brush-paint their first models. With a carefully prepared surface, a good set of brushes, properly thinned paint, some decent craftsmanship and a ton of patience, truly amazing results can be achieved. But for the best results, you should really use an airbrush.
Airbrushing is very similar to painting with a spray can, but is much more exact and precise. The basic airbrush setup consists of the airbrush itself, a paint container and an air supply. The air supply is connected to the airbrush with a hose.
The body of the airbrush is a hollow tube. When you press down the trigger on the brush, air will start to flow through the body of the airbrush. When you release the trigger, the airflow will stop. The harder you press the trigger, the more air will flow through the airbrush.
A paint cup is attached to sides or the bottom of the airbrush body. As the airflow starts, paint is sucked from the paint cup and through the airbrush. The paint is mixed (atomized) with the air to microscopic paint particles, and is emitted through the nozzle of the airbrush as a very fine spray.
On more advanced airbrushes, the trigger can not only be moved down and up, but also backwards and forwards. This action of the trigger controls the amount of paint in the air/paint mixture. Such airbrushes are called double-action airbrushes and generally allow a far better control of the painting than single-action airbrushes.
With practice and a good airbrush, you can not only paint broad and even surfaces, but also fine, almost pencil-thin lines. You can obtain all sorts of paint patterns and effects, that cannot be duplicated by either spray painting or brush painting.
Airbrushes always need some kind of air supply. There are mainly two different kinds of air supply you can use: compressed air cans, or a compressor.
I might as well say it right away: air cans are by far the worst source of air you can use for your airbrush. First of all, they are quite expensive, and will, in the long run, add up to more money than a cheap compressor. But this is only the smallest of the troubles awaiting you if you go for this solution.
The worst thing is that air cans are only capable of delivering enough pressure to pull the paint through the brush for a very short time. You will only be able to paint for around half a minute before the air can cool off and stops delivering power to the brush. You will now have to wait for like five to ten minutes before you can use the airbrush again.
And also as the pressure drops, the mixture of air and paint inside the brush changes so that the airbrush will start spitting large gobs of paint onto your model. Trust me, after a few attempts you will definitely hate painting and modelling.
A far better air supply is a compressor. Just about any kind of compressor will work with airbrushes as long as they have a pressure regulator. The cheapest compressors are diaphragm (or membrane) compressors. Generally, they don’t have a holding tank, which means that they tend to pulsate slightly. To eliminate these fluctuations, some membrane compressors have a built-in micro-tank. I recommend getting one of these if you plan on building more than one or two models a year or if you are a perfectionist.
Airbrushes are of rather expensive. A decent airbrush set with an air tank and a compressor as air supply add up to a pretty hefty investment, but if you plan to continue building models for at least a few more years, it’s very well spent money. Investing in an airbrush kit will revolutionize your modelling more than anything!
As a rule of thumb, the compressor should be able to deliver 30 PSI, and the paint should be thinned to the consistency of milk. If your compressor cannot deliver 30 PSI, the paint must be much thinner, and you will have to paint twice as many layers – for light colours such as white, you may have to paint 20 or even 30 layers! By getting a decent compressor in the first place you can prevent a lot of headaches later on!
Once you decide to move to airbrushing, do yourself another favour and stay away from the cheap beginner airbrushes. Go for at least a semi-pro airbrush with internal atomizing where the paint is mixed with the air inside the airbrush body. External atomizing airbrushes create a much more coarse and rough paint spray, quite effective for painting large areas, but not very suitable for fine-scale model building.
I am a happy user of a Badger 175 Crescendo airbrush together with a Werther compressor – it is a fairly cheap and very usable setup and I would recommend it to anyone.
Before you reach for your superbly detailed 80 dollar model as your first airbrush experiment, I recommend that you do some basic exercises first. If you haven’t used an airbrush before, you will definitely need it!
Create a mixture of water-based ink and water. Make sure it is dark enough to be visible in thin layers. Load the paint cup with some of this mixture and start practising on a sheet of discarded newspaper.
Spend some time drawing pictures freehand, to get used to the airbrush‘s action. Write your name with it. Pencil in some guidelines and practice spraying a straight line of uniform width. Then make two straight lines of the same uniform width. Another classic exercise is to draw a grid of lines, a few inches apart, and spray a dot on each intersection, each dot the same size.
When you’re done, don’t forget to practice washing the ink out of the airbrush.
When you start to feel confident about the airbrush, load some paint (preferably acrylics) and start painting on scrap parts.
It takes some time to learn how to achieve a good result with an airbrush. The only way to learn is by practising, and not being too frightened of messing up from time to time. Don’t be overly hard on yourself: modelling is supposed to be fun!
One thing is very important to remember though – paints must be thinned much more when used with an airbrush than with a regular paintbrush. If the paint is too thick, it will clog up the airbrush and you will get a bad result.
Besides the problems and their solutions that we already covered in the chapter about basic painting techniques, airbrushing has some additional problem areas:
Usually caused by having too low air pressure from the compressor. When using air-cans to drive an airbrush, sputtering is almost impossible to avoid, since the cans lose their pressure very quickly. Before you know it, the airbrush will start to spit large gobs of paint on your model. Don’t say that I didn’t warn you about air-cans!
Finding the correct pressure for the kind of paint you’re using is not easy, but after a while, you will learn the sound and the feel of the airbrush when it’s working fine. By the way, spitting can also be caused by too thick paint or a clogged up airbrush nozzle.
Orange peel effect
This happens to everyone while using an airbrush – suddenly the paint finish looks coarse and bumpy, just like the peel of an orange. This is usually caused by airbrushing with too low air pressure or brushing too far away from the surface. The reason for this effect is that the microscopic paint particles dry up a little bit and gather in tiny droplets while flying through the air onto the model surface.
The best way to avoid this is to find the right balance between paint/thinner ratio, air pressure and paint distance. It’s really not that difficult but takes some time to work out.
Once you have an orange peel effect, the only solution is to gently sand the surfaces with a fine grade wet-and-dry sandpaper to remove the lumps and bumps. Keep the sandpaper wet all the time so you don’t scratch through the paint. When the paint finish is smooth again, wash off all the sanding residue, and let the model fully dry before repeating the painting.
If sanding off the orange peel effect seems like too much trouble, you can just leave it as it is, and remember to improve your painting skills to the next model.
Very simple to avoid – keep painting only feather-light layers for each application and let the paint dry between each layer. When painting very light colours, such as white or yellow, be prepared to paint at least six, seven or even more layers.
Don’t rush! If you think it is too much waiting, you can build several models at once. Then you have always something to work on while one model is “idling”.
When painting a model with more than one colour, it may be difficult to obtain a good and clean line between the colours. Sometimes you want a sharp demarcation line between the two colours, and sometimes you want them to “blend” or fade into each other. Military camouflage paint schemes have seldom sharp paint edges, but more often display “feathered” edges or some kind of “mottling”.
This kind of paint scheme is very hard to achieve with brush painting, and you should really use an airbrush. But what do you do when you want to paint an area without spraying paint all over other, already painted areas? The answer, of course, is by using masking techniques to protect the areas you don’t want to be painted.
When using an airbrush, think of the paint as sunlight falling onto your model. Masked off areas are shadows, and exposed areas are exposed to the light. Masking can be done by using self-adhesive tape, frisket paper or just ordinary paper cut and held in front of the area to be masked off. There are also different masking fluids (like Maskol) that can be brushed on and after the painting simply removed. I have had some rather bad previous experiences with Maskol discolouring the paintwork underneath, and I cannot, therefore, recommend it.
For sharp edges, you must make sure that the masking material is tightly attached to the surface because the paint has a tendency to “bleed” or leak under the mask. Also, try to paint “away” from the mask. When the paint has dried, carefully remove the mask without chipping the paint edges. The best masking tape I have used is Tamiya Masking Tape, which I can strongly recommend.
To obtain a “soft” edge, another approach must be taken. If you are skilful and work with larger scales (such as 1/48 or 1/32), you can, in fact, paint the camouflage by freehand, using the finest available needle of the airbrush. Another method is to make small beads of blue-tak, and gently attach these just inside the area to be masked. Now cut a mask from paper with the correct shape, and attach this paper to the beads of blue-tak. This way, you will have a mask that “hovers” slightly above the surface to be painted. If you now airbrush gently and carefully, you will be rewarded with a clean and slightly feathered paint edge.
The main rule is, the larger the beads, the higher the mask will hover above the surface – the more “fuzzy” the paint edge will be. Smaller beads, closer mask – sharper paint edge. Of course, you will have to airbrush from straight angles to the mask, or you will spray paint under the mask.
Another simple trick is to use regular children’s play-doh to mask off the areas. I would not really recommend this method, as play-doh can leave an oily film on the paint, which may make it difficult to seal the paint with clear varnish later.
When you are painting the major parts of the model, such as the fuselage and the wings, remember to paint every detail that is going to be attached to these surfaces. Paint all the airbrakes, flaps, slots and landing gear bay doors at the same time or you may find it very difficult if not impossible to obtain the same colour nuance and paint glossiness later. Glue these parts in place at least temporarily with blue-tak or a droplet of white glue before masking and painting. I cannot tell you how annoying it is to discover having forgotten painting airbrakes or wing flaps and ending up with slightly different coloured parts.
I also recommend painting the canopy at the same time to make sure that the frames have the same colour as the camouflage, or it will just stick out like a sore thumb on the finished model. I have done this mistake more than once on my models!
Okay, I admit it. I do cheat on this subject. I have been spoiled by Eduard’s pre-cut canopy masks. They are available for many kits, reasonably priced and save a lot of time. In most cases, they don’t need modification. However, a new xacto blade will trim them if necessary. Eduard supplies a diagram for placing and will include additional masks for other clear parts in the kit. I highly recommend this product, especially if there is a complex canopy in the kit.
There are several masking products on the market that make this job much easier. Some conventional, some not. There are some brands of masking tape that strictly cater to modeling but they tend to be very overpriced. Here’s a list of inexpensive products I find useful.
- Good ole’ 3M painters blue mask tape for delicate surfaces. A large roll is cheap and will last a long time. It can be used for all hard-edged applications and will bend nicely to contours if thin strips are cut.
- Post-it notes are excellent low-tac masks for quick jobs or for covering large areas that you don’t want paint on. There are several sized pads to choose from.
- Liquid mask is a gel that can be brushed on. When dry, it acts as a mask and can be peeled off afterward. This product comes in handy for hard to reach areas, canopies,
or awkward compound curves.
- Sponges are great for filling large areas prior to painting. A fine sponge can be cut into shapes and stuffed into areas such as cockpits, wheel bays, open bomb bays and doors.
- Yep, that’s right……Silly Putty! Silly Putty is an excellent mask, especially for camouflaging and irregular lines. It can be molded to any shape needed and conforms to angles. The putty is easily removed, leaves no residue and can be reused over and over. This method is far faster than cutting conventional mask for complex schemes.
Finding the Right Colours
Sometimes finding the correct colour to use for a part or for the whole model can be quite a tricky business. Most model kit manufacturers provide a painting guide, but more often than not, this guide is not quite correct. Sometimes the manufacturer refers to a certain brand of paint (such as Humbrol), while the real colours fall “in between” two given colours.
Other manufacturers refer to the exact colour nuance using a standardized colour description (such as the FS-designation). But even if you’re using the exact colour, your model may still appear “wrong”. Quite often the colours seem too dark or having too much contrast. The reason for this is the scale effect on colours.
Think of the following: if you are looking at a model in scale 1/72 from a distance of one foot, then it should be like looking at the real aircraft from 72 feet Now, 72 feet of air is not quite transparent – it has a certain amount of “haziness” or “blueness”. To simulate this effect, your colours should be “toned down” somewhat (a small amount of white mixed in) to give the correct appearance. Some brands of paint (such as the AeroMaster WarBird-series) already have this “toning down” effect built in – they are actually a shade lighter than what’s printed on the paint jar.
The best way to find the right colours to use is really to use your own references. Look in aviation and modelling magazines. Search for photos on the Internet and compare several different models of the same aircraft. Finally go for your instincts – quite often what seems right is correct!
Unfortunately, a normal painting will not always get you all the way to the finishing line. The problem is that not all aircraft are painted; many of them are flying around in their natural metal birth suit. Representing this metal surface may very well be one of the most difficult jobs you will ever face during your modelling career, and many modellers tend to shy away from natural metal finishes.
But unless you’re extremely hard on yourself, things are not so bad, though. There are many metallic acrylics and enamels, which can be painted on using normal methods and will create a fairly believable representation of a metal finish. Keep in mind that a good priming with white or light grey is more essential than ever because metallic colours are transparent. An unprimed surface will show through no matter how many layers of metallic paint you paint on.
If you feel like a challenge and wish to try to achieve a truly authentic and amazing result, you can try so-called metalizers.
There are several different brands of metalizers available in the shops (such as Model Master, Liqu-A-Plate, SnJ or Alclad II, to name a few). The way you use them is basically the same: first prime your model with a smooth primer (such as Halfords grey). Next, spray your model with the metalizer using your airbrush. Then, just before the paint is totally dry, take a soft fluffy rag or cloth and “buff”, or rub the metalizer. By doing this, the metal particles in the metalizer will form an opaque metallic finish. Basically, the longer you buff, the more lustre you will get out of the metallizer. You can even achieve a near mirror-like finish!
Metalizers can be a bit tricky to work with since they require an extremely well-polished surface to do their best – even the slightest imperfection or scratch below the metal finish will be very visible. The earliest types of metalizers are also highly sensitive for handling and the surface cannot be touched. But more modern metalizers can be sprayed on just like any paint as long as the surface is extremely smooth and has been primed with a good primer (such as Halford grey).
One of the best metalizers that exists today is the Alclad II. No buffing is necessary and the surface is tough enough to handle masking and normal handling. There are several different metal hues to choose from, like dural, aluminium, titanium, burnt metal, copper and chrome. The result is absolutely fabulous and unrivalled by any other painting methods.
A different technique to recreate the look of an unpainted metal surface is the use of bare metal-foil. With this approach, the metal look of the model is achieved by “wrapping” the parts with a self-adhesive metallic foil. While some model builders swear by the bare-metal foil technique, I have so far never succeeded with this method and I don’t think that I will ever try again.
There are always some parts of the model that will grab people’s attention, as I have already mentioned. For aircraft models, one such area is definitely the cockpit area and the canopy. Every minute of work done in this area will improve the model in a much higher degree than the same amount of work done for example to the underside of the wings.
The cockpit on most modern aircraft is partially hidden under the windshield and canopy. Other aircraft can even have much more complex glazed areas, such as the nose areas of WWII bombers with their intricate glass panel birdcages. Even the simplest one-piece canopy is quite a challenge for model builders, as you normally want to paint the canopy frames, without painting the glazed areas.
There are many different techniques to create good looking frames, such as free-hand painting, masking, using tapes and decals for the frames or even using etched brass canopy frames.
Most model builders start by painting the frames by hand. I still like to do it on models where the edges of the frames are represented by thin raised lines. By using these lines as guides, it is possible to paint very fine and accurate panels using a fine brush, thin paint and some patience.
A different and easy technique is to use empty decal sheets (decal sheets without anything pre-printed). These decal sheets can be airbrushed with the desired colour, cut in thin strips and attached to the canopies just like regular decals. The result is most often very nice and neat!
I heard a competition modeler once say that a model’s finish is the first thing anyone sees when approaching the model. I certainly buy into that theory. The overall finish will have the biggest impact on the appearance of a build. So, we should make it the best we can. There are steps that I like to follow in order to ensure a nice paint job.
- After construction, wash the model well with liquid soap and warm water. Use an old toothbrush to scrub all crevices and panel lines. Rinse and let dry completely.
- From this point on, I will wear a latex medical glove (powder free) when handling the model. This will keep any fingerprints off. Also, mask any open areas such as cockpits, wheel bays, intakes, etc. Pieces of wet paper towel or small sponges make excellent form-fitting masks.
- ALWAYS prime your scale model aircraf. Priming will be a live saver when it comes to any type of masking. I use acrylic paint, so I prime with acrylic paint. Before I apply it, I will blow off the model with my airbrush at 30-40 psi. This gets rid of any dust particles that have settled. I don’t have the luxury of a spray booth. So, I turn off any ceiling fans/central unit and make sure there’s no dust moving around.
- After the initial primer coat, I will inspect for seam and joint issues and correct if needed. The primer will expose flaws in the construction. Now is the time to fix them. If a repair is made, clean the area well and re-prime it. Let the primer dry for at least 24 hours.
- Sometimes acrylics can give a gritty, rough finish after they dry. If this happens, use a small grit polishing pad to sand the areas smooth. There will be no damage to the finish IF the primer has cured. For best results, each color coat applied should be as smooth as possible and lightly polished if need be.
- Now is the time to apply all color coats with a 24 hour dry time between colors. Once again, I will lightly sand each if necessary. It is best to apply all light colors first and darker colors last. Dark colors will bleed through a lighter color and require more layers of the lighter color. This may affect any detail in the area and create “ridged” separation lines between colors.
- At this point, an acrylic gloss coat is applied for protection and decaling.
Paint Additives and Thinner
There are a couple of products I use that make the painting process much easier. They are Liquitex brand slo-dri and flow-aid. Keep in mind, they can only be used with acrylic paint. Slo-dri slows the dry time according to how much you mix in. It also acts as a thinning agent. Slo-dri will help give the paint a flatter, smoother finish and eliminate any gritty texture. Flo-aid increases the flow and workability of the paint. A small amount added to the paint will help stop the airbrush tip from clogging. I highly recommend these products for each and every paint application.
As far as thinning acrylics, I use and recommend isopropyl alcohol (70 or 90%). Thinning is not an exact science and there are no set ratios. The general rule is the paint consistency should be that of skim milk. That will give you an approximate ratio of 60% paint and 40% thinner, give or take. Some brands of paint are thicker than others. So, more thinner may be required in that case. When I mix a batch, I use incremented measure cups to eliminate the guesswork.
For airbrush clean-up, I recommend standard lacquer thinner. Between color applications, I will run some through the airbrush for a quick cleaning. After use, the airbrush will be broken down and cleaned.
Polishing a Finish
Either flat or gloss finishes can be polished which will remove small imperfections, dried paint flakes and dust embedded in the paint. Polishing will not harm the paint surface IF the paint is cured. I always allow at least 24 hours and 48 is even better. Very fine grit (8000-12000) pads or paper can be used. Pads are cushioned which allow a softer “touch” and easily bend if too much pressure is applied. For anyone who uses acrylics exclusively, I highly recommend the pads.
Modelers sometimes have problems with their final clear coats, especially the flat coat. The biggest complaints are hazing or a white, dusty appearance. Sometimes, this can ruin a nearly complete model. There can be a couple of reasons for this. First, too much was applied and there is a build up. The thick layer will appear white and flaky. Second, the individual brands give different results. Some products are real flat while others give more of a satin finish. If the coat is too flat, it will also appear hazy and rough. Model Master acrylic clear coats are famous for really flat coats and these are the ones I use. So, to avoid these two issues, here are a couple of tips for application.
- When thinning, add some Liquitex slo-dri just as you would for color painting. Again, slo-dri will let the coat dry slower and smoother. Also, if the paint remains wet, you will see the wet paint and discontinue spraying that area. This will eliminate overspraying which leads to building up.
- Mix semi-gloss with the flat clear. This will produce a cleaner, invisible clear coat without any discoloration or hazing.
2 parts semi-gloss + 1 part flat + thinner/slo-dri
* the thinning ratio should be the same as the color paint (60-40)
Natural Metal Finishes (NMF)
Now, I will break away from the acrylic paint and address two other products for metal finishes. NMF’s can be intimidating and do take practice.
However, once you get the hang of it, the results will be worth it. My personal choices for this finish is lacquer based metallic paint or metal foil.
Below, I will discuss methods for each.
Alclad II and Model Master metallizer
I find these two products give a very convincing finish. Both are lacquer based and do not need to be thinned nor can they be brush painted. An airbrush is required. If you have no airbrush, Model Master offers their metallizer in a spray can as well. Lacquer thinner in needed for clean-up. Alclad offers several metal types and shades. Two or three shades of aluminum can be used to simulate shade variations on certain areas of the model.
Construction of your model will have to be near flawless. The paint will exaggerate any blemishes, seams, scratches and glued joints. The model surfaces will need to be very clean and smooth. Probably 90% of modelers will prime before using these paints. I choose not to. Sometimes, a primer coat has the tendency to create additional surface imperfections and may require extra work. Plus, lacquer is a very “hot” solvent and will adhere much better to plastic than enamels or acrylics. So, I feel priming is unnecessary. I’ve had no problems yet with these paints lifting or scratching. Here are a few things to keep in mind.
- Spray these products in a well-ventilated area with a respiratory mask.
- Apply at a low psi. 10-12 psi should be sufficient.
- Spray several light coats with a small dry time between each. About 10 minutes should do.
- Allow to dry for 48 hours. Especially if you intend to apply other shades of aluminum or other paint on top.
- This is a matter of preference but a clear coat is not needed. Clear coats may diminish the metallic sheen and appearance.
- This finish can be polished with a very small grit sandpaper (8000-12000) for more lustre and to remove paint imperfections.
- Test spray an old model first. This will allow you to experience the behavior, application, and workability of the paint.
- Unlike Alclad, the Model Master metallizer line will have to be sealed with their metallizer sealer. Sealing the finish is necessary for masking and additional painting.
This process is more time consuming, expensive and harder. However, the final effect is impressive. Nothing looks like metal more than metal. The Foil comes in several different shades and has an adhesive backing which sticks very well to the model. Matte aluminum is my choice for aircraft and car trim. It can easily be cut and trimmed with a new Xacto blade. These are some steps to follow
when using foil.
- Once again, the model will need to be clean and well constructed. All large surface areas should be smooth with no blemishes. The foil will expose any flaws or particles that get trapped under it.
- Remove the foil from the backing very carefully. The foil is thin and will tear and wrinkle easily. Lay it on the area to be covered and let sit. Do not let it stick in place yet. Cover large, flat areas with one piece.
- Start at the center of the area and burnish the foil down with a Q-tip. Gently rub from the center outward in a circular motion. Q-tips will flatten the foil and get rid of any small wrinkles without scratching or ripping the foil.
- Choose a panel line or joint as your stopping point for that piece and burnish the foil to that line. Use a toothpick to lightly outline the panel. Joints and panel lines should be used for combining several pieces of foil to the entire surface area. These panel lines will hide the overlap lines of the foil pieces.
- Cut the excess foil away by using a new Xacto blade and tracing the panel/joint line with the knife. Use very little pressure when cutting. Remove the extra foil with tweezers.
- The foil is fairly pliable and does stretch. So, it can conform to curves to a certain point. Smaller pieces will need to be used for curved areas so the tendency for wrinkling and folding will be lessened. If the curvature is too severe for the foil, such as external gas tanks, cowlings, and intakes, you can paint the area with the metallizers instead. The substitution will go unnoticed.
- Any recessed surface detail can be burnished down with a rounded toothpick. Run the toothpick in the recessed areas and the foil will settle into the detail. Be gentle though, the foil could tear.
- This is the nice thing about foil. If you screw up, pull it up and start over. If you pull up a piece, you will have to use a new piece. The adhesive backing is a one-shot deal. Plus, some adhesive will remain on the model. Some Windex or Simple Green on a Q-tip will get it off.
- Paint will stick to foil but not well. Both enamels and acrylics will stick if you let it be. If you mask or accidentally scratch the area, the paint will come off. So, painting on top of foil should be the last thing you do with the finish.
* Once again, a clear coat isn’t necessary. It will alter the appearance of the foil.
Holding Small Parts
Here’s a couple of inexpensive ways to hold small parts for painting. Materials can be found at any hobby or craft store.
- a block of styrofoam or a floral arrangement foam block
- popsicle sticks
- plasti-tac putty
Painting is not as easy as it seems and sometimes you end up with a less-than-perfect paint job. The most usual problems and their causes are the following:
Caused by the evaporation of the solvent (enamel thinner or water). When painting for a long time, pour some of the paint into a separate container, and use this as your working paint storage in order to avoid your paint jar to dry and thicken. Be careful to wipe off any excess paint or runs from the rim of the paint jar before putting the cap back on.
If the paint has become thick, you must thin it before you can use it. Use the recommended thinner for the brand of paint you are using. For acrylics, use distilled water.
Runs and drips
Usually caused by applying too much paint at one painting session. When a primer is not applied first, usually too much paint is used in an attempt to achieve an opaque coverage. To avoid this, apply several thin layers of paint instead of one heavy layer. For light colours such as white or yellow, be prepared to paint at least three or four thin layers until a full coverage has been achieved.
When the paint appears watery and shows very low coverage or collects in “beads” on the model, usually it is because the paint is not properly mixed with the solvent. Merely shaking the bottle is not enough; you should stir the paint thoroughly with a round toothpick or an ice-cream stick.
This problem can also be the result of over-thinning the paint with too much thinner. It is not easy to thicken the paint to the right consistency without adding more pigment, but you can sometimes just let the paint jar stand open for some time and let some of the solvent evaporate.
Melting and cracking
If the paint doesn’t seem to dry to a smooth and even finish, if it cracks, bubbles or appears to “melt” the plastic, it is a sign of some adverse chemical reaction. Most often this is caused by having used the wrong type of paint – like automotive or machine paint. Always use hobby paints, designed for plastic models. It can also be caused by mixing two different kinds of paint. For instance, is it not recommended that you mix AeroMaster with Gunze Sangyo acrylics.
Dust and bristles
Before painting, make sure that the parts are very clean. Even the slightest residue of sanding dust will leave ugly bumps and lumps when painted. Always remove all dust and handling grease by washing the model under running water, and then let the model dry for a day before painting.
Always use good quality brushes that won’t leave bristles in the paint. Don’t press on the brush, or the metal collar will cut off the bristles and leave them in your paintwork.
Right after the painting, the finish is very tacky and sensitive. Even the slightest touch will leave a terrible fingerprint. You should always strive to paint in the most dust-free environment you can find, or airborne dust particles will settle very easily and give your painted finish an uneven appearance. Flat acrylics are better in this respect since they dry very quickly.
This problem is very tricky to discover until it’s too late. The paint simply does not bond strongly enough to the plastic. It is easily scratched with your fingers and is lifted right off when using masking tape, leaving ugly scars in the finish.
The usual reason for this is that the plastic has not been washed totally clean before painting. The plastic parts are normally covered with a greasy film as a result of the moulding process. If this film is not removed before painting, the paint will not adhere to the plastic itself, but rather to this greasy film instead. Even the slightest handling could then lift the paint off. To avoid this, always wash off the parts with a tepid water and dish-washing detergent.
Thinned acrylics have a much lower adhesion than enamels. That’s why I would recommend using enamel paints for priming.
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