Adding Scale detail to PNF Foam Aircraft

We are spoilt for choice when it comes to scale RC aircraft and although most manufacturer try to add scale detail there is so much additional detail you can apply. Many of us will be familiar with the terms, ARF, RTF, PNF, BNF and PNP where most of the work has been done for you. A few additional hours to a few evenings is all that is required to take a model to the next level. None of the more traditional model aeromodeling building skills are required in this brave new world, only basic tools and some free time. Some older readers may be disappointed to read less people are learning the traditional model building skills, however  it should be noted that we all share something in common. Flying, and that’s the most important thing. 

Let’s face it, time is in very short supply and not many of us have the time to build beautiful models from scratch. Many of us lack refined skills and even a place to work on models. That is what makes foam ARF or PNF so attractive today. There is nothing quite like grabbing your favorite PNF model for a fly around the park on a Saturday or Sunday morning. Cool air, light winds is where it’s at.


After a while a foam model will suffer from a condition known colloquially as hanger rash. This is the result of landings, storage, transport, and handling. For some models you won’t care to much but what about the one that flies so well you decide you want to keep it forever and that life might not be worth living if your foam princess was no longer with you. The finish on our foam aircraft is susceptible to dirt, dings, grass, weeds and degradation from even minor impacts and no matter how well you fly it the impression of all that neat surface detail sort of falls apart when you get close to the airplane.  


Although our models are almost ready to fly out of the box there is much we can do to ensure the finish stays looking great. The factory has done much of the work for us with a nice finish and decal placement but that is not going to stay like that for long. Probably not because not only areplanes susceptible to the aforementioned causes of hanger rash we missed one. Its glaringly obvious…  The sun! The sun is responsible for much of the damage as it causes the foam cells to expand. Modelers refer to this condition a crocodile skin.

So, we’re going to look at and address the following key questions?

• How do we keep our models looking great?
• What materials can we use to protect the foam and improve the finish and appearance?
• Whilst some products make big claims, what products actually work?
• How do you get the best results from those products?
• Know when to stop and what can you realistically improve on a foam a foam model
• How much weight will that add and will it affect the flying performance by making it too heavy?

Where to start?

I hope to share with you the many products that I’ve come to know and trust over the years. I won’t claim to be the inventor of the techniques we cover in this article, but I think of it more like a set of skills we acquire and continually hone with each new model we finish. 

The first step is of course to assemble the model following the manufactures recommendations. All manufacturers of quality models will include a comprehensive manual stepping out the assembly sequence along with a list of the various components required to successfully assemble the model.  I also take the time to read a few of the reviews in order to verify the suggested CG and assembly advice. I don’t apply decals incase I would like to make some changes or coat the model with protective coatings. Once I have maidened a new aircraft (The act of test flying and trimming out a new aircraft) I then decided if I really love the model enough to invest the time and energy into properly finishing a model and taking it to the next level. 


It’s a keeper. Now what?

At this point we have to decide what to change and how much work is required. Remember that you have to be happy with the model and not some biscuit munching, armchair critique at the club. Provided the model makes you happy that’s all you should really care about. I have been known to intentionally paint a warbird a horrible and absolutely atrocious scale scheme just because I knew it would ruffle some feathers. Again, I liked it and that’s all the matters. 
Create a list of what you would like to achieve. For example, paint, cockpit, decals, scheme, control surface trim tabs or you might want to put a new finish on the model. If your decals were set aside from the earlier build you may elect to repaint a scheme of your own. Remember that these skills are learned over the years so don’t feel like you have to tick all the boxes. Set a goal, achieve it and move one.


Often manufacturers have made a good flying model that looks scale but fail to paint the model properly. Occasionally the colors are poorly matched or feature a gloss where it should have been a matte. Take Dynam as an example. Their models are generally mediocre because they manage to poorly execute the finish on a model. Take their spitfires! it’s a sea of colour that does not look representative of the full size. This is where you can greatly improve the model if you are willing to put in a few hours. Ideally, buy a model where the paint has bee well done and you only need to add custome features like a tail color change and some decals. 


Where Can I draw Inspiration From?

Start by looking at what our plastic modeling cousins are doing. Often plastic modelers are a great source of inspiration and a wealth of knowledge.  Most often they will list what colours they used to achieve their jaw dropping paint job.


Once we know that colours to select you can purchase those pots of paint off the shelf. Be sure to obtain a good airbrush and compressor because it’s something you will use for years and if looked after properly.

Whether it’s for painting models or just for making cool artwork, airbrushing is a respectable skill to learn, and what better way is there to learn and improve than with a high-end professional quality brush? Unlike other cheap brushes which may give inconsistent results, this polished metal gun not only looks the part, but can be used to produce great work.

Airbrushing can add a lot to your model. For many it becomes the “best” parts of the hobby for them. I will try to provide some basics, so you can make good decisions about equipment, and learn how to paint by doing. As for paints- I will focus on the use of acrylic (such as Tamiya as the the acrylics are so much safer and easier to work with. Not only are acrylics easier to paint and clean up, they don’t smell as bad nor take days to dry.


What materials are required

• Painter's Tape or masking tape - professional grade tape is available from most hardware stores and is worth the extra. It goes on better, leaves a cleaner finish and finer edge when removed.
• Newspaper or Paper Towels -  is perfect for protecting the model against under wanted over spray.  You will learn that when using an airbrush or you must mask up every little space where paint could possible enter or penetrate and ruin hours of hard work.
• Respirator Mask – They are cheap and you cannot really put a price on your health. I cannot stress this enough, get a mask and protect you from breathing in the paint particles.  Be sure the mask you use is approved for paint particulates
• Water-Based Polyurethane – This is fairly common these days and primarily used to seal timber floors. Be sure not to buy the oil based Polyurethane.
• Light Spackle Filler – Dings, scratches can all be removed and lightly sanded with a 600-800 grit sanding sheets. Great way to get rid of any imperfections you don't want showing through your new paint job.  
• Primer - Once you have filled any dents and dings and sanded to a smooth finish you will want to spray your model with primer before applying the actual paint. 200-400 grit sand paper sheets.
• Decals - You can of course buy decals or create your own. Callie Graphics is well respected in the RC industry however if you would like to create your own using a laser or ink jet printer the process is simple enough.

The Preparing the model.

If your model is made from EPO foam you can try using acetone to remove the existing paint. Try this in an area where if damage were to occur it would not be noticed.  Perhaps a wheel well, the inside of the model etc. Acetone is water soluble so the moment it is hydrated any damage the acetone was doing is neutralized. Acetone is easy to fine in any hardware store and is reasonably cheap
Start by fixing any blemishes,  dings, dents or damage to the foam by using  a light spackle filler. This spackle sands very easily and is somewhat consistent with the foam around it.  Apply the filler evenly and smoothly to the ding or dent using an a flat card or putty knife.  Be sure to use as little as possible because you will need to sand it it a smooth finish. If necessary, apply and sand twice to get it right. Once you’re happy move on but not before. Paint will not hide blemishes and will only serve to highlight the imperfections.

Before you apply paint you should clean the model thoroughly. I use a vacuum cleaner and the soft attachments to get as much dust as possible from the model. I also blow the model down with a jet attachment on my compressor. Try not to vacuum or blast the model down in a room where you will immediately paint as those particles will settle on your model. Now it’s time to seal it and protect the model before we paint. I water down the polyurethane clear coat and spray it all over the model. This soaks into the surface of the foam hardening the surface and giving us an excellent surface to paint on.


If your model has many colours and requires masking you must paint in order. Light paints first, so this is white through to black. This is the most tedious task however it is the most important step and you should not cut corners. If you want a finish to be proud of this is where you should focus all your attentions making sure you apply the tape firmly. Make sure the tape is stuck down well so that paint cannot enter underneath as the finish will be poor.  This is where good quality masking tape is so important. The bond must be strong enough to stop the paint bleeding but soft enough to so that the paint is not lifted when you remove the tape.  Paper towel or paper sheets can now be used along with the tape to mask off the rest of the rest of the model so that only the areas we want to paint are exposed.


As discussed earlier, if you can remove the old paint back to white foam do so.  This will result in a better finish without requiring several more coats of paint to hide the original paint. The less paint you put on the model the lighter the model will be and the better it will fly.  Paint is heavy and additional weight all comes at a penalty

Ready to paint?

Take your time and get used to your airbrush. Add a little paint to the jar or cap and start spraying on a test piece. Get a feel for the pressure required along with how it flows. Most model paint manufactures will make suggestions on the additives and the mix rates for best performance and finish. You will find that environmental factors also make a massive difference with temperature and humidity playing a massive role in the end result.  Remember; apply light and even coats allowing the job to dry in-between applications. Avoid spraying in one place for any length of time but rather keep moving in a sweeping motion.

Once you have put down your first light coat, allow it to dry completely and don’t touch the paint. Rather you can touch the paint on some of your masking tape if you must it. If it feels dry, apply another second coat and repeat this process until the paint has completely covered your model.  Avoid the temptation to apply paint too quickly because if the area becomes saturated the paint will run and the thinners may dissolve earlier coats. Take your time.

Once the paint is dry you can remove the masking tape. Never pull upwards, but rather gently pull backwards and gently. You do not want to pull up any paint back with the model. Some people suggest waiting 24 hours however I prefer to remove the tape once the model is dry and I do this to stop paint being lifted with the tape. I have found the longer you leave the tape the greater the chance of removing the paint, so this helps the tape pull away cleanly without pulling up paint or foam material.  Once you have the tape look closely look for any overspray or paint bleeds. We can correct this in two ways, a hobby paintbrush or mask, cover and spray gain.  Don’t cut corners here after all of your earlier hard work.

Clean your airbrush nozzle after each coat.  Paint nozzles get clogged easily and they also build up paint around them which if left can spray out later onto your model. Also a buildup can lead to a poor finish or splatter on the model. Paper towel can be used to remove an excess paint from the nozzle after each coat. Don’t forget when washing your airbrush to get out all the paint every time so that your airbrush continues to give you years of reliable service, year after year.

Happy with the paint work?

Yes! Great, now it’s time to seal the paint as we did earlier. This will give the paint a fighting chance against hanger rash and the best surface for decals to adhere to. I water down the polyurethane clear coat and spray it all over the model but don’t mix alcohol with the polyurethane. A chemical reaction takes place and it starts to coagulate and becomes useless.  I spray a light coat over the model and I give a few extra coats only to the areas that generally receive hanger rash. Areas like, leading edge, wing tips, nose and elevators.


Water Slide Decals

Waterslide decals are by far the most popular way of applying markings and other graphics to scale models.  This is partly because most model kits are supplied with appropriate waterslide decals, but also because they generally work very well in most situations and it is relatively easy to get a good result. Waterslide decals can vary considerably in quality and material so definitely try different sheets until you find something you like. Sometimes they are too thick and will stick out on the surface of the model and will not lie flat over surface details.  At other times, they may be too thin and might disintegrate during the application process.  If the printing is not sufficiently opaque the underlying colour of the model will show through.  Occasionally, they may be printed out of register where the different colours are not printed over each other in the right place.  However, standards have been continually increased over the years and the vast majority of decals are now very good quality. Decals that are applied well will greatly enhance a model, but when they are applied badly they will ruin a model that otherwise would have been excellent.  Providing a few basic rules are followed, it is quite easy to get good results.

Allow your model 24 hours to completely dry before applying decals. If the model is not completely dried and cured the decal application process may cause the paint to release from the model. Don’t undo so much hard work and it will be a massive disappointment and take a long time to correct.
Depending on the decals chosen you will need a few simple tools

•  Model Decal sheet (Cali Graphics or print your own)
• Saucer of water + a drop of dishwashing liquid
• Tweezers
• Small brushes (one for each decal solution)
• Small scissors
• Paper towel

The Process

  1. Cut out the decal to be applied and leave the carrier film intact if possible, but where this will make the decal too big for the area where it is applied, or where there is an irregular surface it may be best to cut right up to the printed decal area. 
  2. Place the decal on the surface of the water and leave it for 20 or 30 seconds.
  3. Remove the decal from the water and place it on paper towel to remove any excess water.
  4. Paint a layer of decal solution 1 on the model where the decal is to be placed.
  5. Slide the decal off the backing paper on to the model.  Using a paint brush is a good way to do this without damaging the decal. Try to move the decal as little as possible pulling the backing sheet away from it. Use the brush to hold the decal in place whilst you slide the paper out
  6. Use the brush to position the decal.  When you are satisfied with the position of the decal press paper towel on top of the decal to absorb excess water.  It is normally possible to reposition the decal by dampening it with more solution and sliding the brush underneath it. If necessary, brush a layer of setting solution 2 on to the decal then leave it alone to dry thoroughly. Don’t touch the decal not matter what it looks like after you apply decal solution.
  7. When the decal is completely dry you can spray with diluted polyurethane to seal and blend the decal into the model. When a decal is applied correctly, it will look as if it has been painted on.

Replacing the Pilot

Some manufacturers include a pilot and some do not. Often you’ll find a pilot that is just god awful and it needs to be removed and discarded. Whilst I’m sure many don’t mind, I do and I like to pry him out and put in a new one. There are so many good ones to choose from with some being quite reasonable and some costing almost as much as a new foam PNF.
Finding a reasonably priced pilot is not too hard. Hobbyking have a couple that I’ve used before and they are not going to break the bank either.
The process to replace the pilot is fairly simple one. Start by gently prying off the canopy and this is where you must take your time. Don’t rush this as you might accidently remove paint or worse break the canopy or damage the model.  To fix the pilot to the canopy you should use a contact adhesive and avoid glues like CA. This is because CA glue vapor has a tendency to mist up the cockpit window. Whilst you have the cockpit open it is a perfect opportunity to add more detail. Gauges can easily be added with decal transfer paper. To fix the canopy to the fuselage use a contact adhesive and again, avoid CA for the reasons above.

Happy Painting and as always Happy Landings!
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