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Thread: Painting a Hard Body - Tips

  1. #1
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    Default Painting a Hard Body - Tips

    Apply a nice finish on Plastic Model & RC Bodies using spray paint from cans

    Supplies needed (based on a Tamiya Hilux body using Tamiya Spray supplies)
    -Tamiya Surface Primer
    -Tamiya Spray Paint (code TS-XX, XX representing the paint code number)
    -Various grades of sand paper from 600 – 1200 grit
    -Hobby Knife
    -Dish soap
    -Paper Towel

    A few requests for this and I’m finally getting to it. I’ll start with simple text directions and will add images the next time I spray a hard body. Please keep in mind this is the process I take to do my paint jobs, personal techniques may vary.

    Building your skills as a painter is simply a matter of practice and using the proper products and techniques and most of all taking your time and having patience. I’ve always used Tamiya & Testors products and these are my personal preference.

    In this example I’m using Tamiya Synthetic Lacquers because they’re readily available at most hobby shops and the finish is fantastic when used properly. 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.

    The most important 2 things to remember are …

    1.Paint isn’t filler!
    2.The end finish is only as good as the prep work


    A nice paint job should complement the body’s details not hide them. Your paint 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. The best paint jobs begin with a well prepped surface.

    This process can take up to 3 days depending on the quality of finish you're after but this is the difference between a hard body build and spraying polycarbonate…you're doing this for detail!

  2. #2
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    Default Prep

    Step 1 Preparing the Body
    First things first…after trimming off the tabs from the parts trees I wash the body and parts in hot soapy water to remove any mould releaser. I do this before any prep work to make sure the releaser isn’t ground or pushed into the surface by sanding or scraping.

    Most of the ABS bodies we deal with are injection moulded. This process leaves behind some unwanted ridges that need to be removed before getting to the basic prep work on the body. To remove these left over material, I use a sharp hobby knife to trim off most of it, then turning the knife sideways I drag the knife edge across to remove the balance of the material until it’s almost flush with the body panel. I find this gives better control and gradually removes material lessening the odds of slipping and cutting into the surface. To finish I use 600 grit wet sand paper to complete the area and prep for the first layers of primer.

    Next after soaking 800 grit wet sand paper for about a half hour I gently sand the entire body (using the palm of my hand…not fingers). I follow this up with a Extra find Brillo Sanding pad to be sure to get in all the contours.
    Last edited by UNGLEWD; 05-25-2009 at 05:14 PM.

  3. #3
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    Step 2 Priming
    After the surface is prepared, washed and completely dry it needs a thin coat of quality primer. For the paint to bind properly to the surface of the model, it must be free from oils, dust and other contaminants. After the body is completely dry I use a tack cloth to take off any dust that may have fallen onto the body while sitting

    No matter what brand paint product I use on a body I always try to use the same brand primer…these products are developed and matched chemically (usually) to work best with each other. I use Tamiya Primer regularly and am always pleased with the results.
    Priming is necessary for a few reasons…The primer works as a filer for FINE scratches (moderate scratches should always be filled with a quality spot putty first), after sanding it helps the paint adhere properly & finally gives a uniform coloured foundation for your paint job.
    Normally I use Tamiya's gray Fine Surface Primer as it gives a good starting point and middle of the road base for both dark and light colors. White and tinted primers are also available if you prefer to start with a closer match.

    Shop temperature: 75 – 80 degrees

    I always start by fogging on a light mist over the entire body, this gives me a clear indication that there’s no reaction like fish eyes from contaminants. I gradually increase the amount of primer over 3 light coats until there’s full coverage.
    This is where the patients comes in…..Let it sit overnight in a warm controlled environment. Both primer and paint soaks in settles & sinks and letting it cure overnight allows it to do so. The following day the surface can be sanded smooth using 800 grit wet sand paper, keeping the body and paper wet and rinsing regularly to remove the sanding film and keep the paper clean.

    Grey primer’s great for highlighting any defects or imperfections, looking down the side towards a light should show any marks that need attention. 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 the final priming, set it aside to dry for at least 24 hours. Even coverage of primer is very important so if you break through the surface, prime the spot and start again.

    For final sanding I prefer to use 800 grit paper in combination with an extra fine Brillo Pad to get into the grooves.
    Usually I’ll build a stand for the larger parts to rest, makes it much easier for handling. I cover the box in fresh paper and tape after washing, blowing off and tacking the body. This makes it so much easier to handle during spraying and gives you a safe platform to hold the body up while drying.
    Last edited by UNGLEWD; 05-25-2009 at 05:17 PM.

  4. #4
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    Splashin on the Colour
    Here’s where you’re great prep work is going to pay off!
    Knowing how paint works helps greatly when putting on a great finish… 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 surface as you are painting it and make adjustment to compensate for variations before they become problems.

    Like any paint, the pigments in a spray can tend to settle to the bottom and need to be re-mixed with the binders. I prepare my cans by shaking or swirling the bearing in th ecan around for about a minute and then placing them on a warm (not hot) heat source until the entire can is warm to the touch. After that I shake again for about 2 minutes. Making sure the paint is properly mixed is crucial! 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.

    A quick explanation on getting the paint to flow (borrowed from the Tamiya website….well worded)
    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 being why the directions suggest a certain distance between the body and your nozzle! 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.

    Getting to it!

    Before you even point that can at the body do a few test squirts to be sure the nozzle sprays evenly (a fine mist)

    When spraying, never start or stop the spray over the surface of the model. Start the spray past one side/corner of the body and make smooth even passes from one end to the other, stopping the spray after the paint stream has passed the end of the model. The more graceful and accurate the pass is the better chance of getting an even finish and equal amount of product on the surface.

    Much like the primer steps I like to fog on a very thin coat at first and let it tack up well before applying a second. This way if any issues pop up like fish eye, marks or dust it can easily be fixed before continuing. If the above steps have been taken you can usually get a nice finish with 3 coats. As soon as the last layer tacks up a bit (stick your finger to the box where there’s overspray) it’s ready for another coat.
    Getting used to painting using spray bombs takes a bit of getting used to but with a bit of experimenting and practice it won’t take long to see what is happening as the paint goes on the surface.

    Is it going on too dry or too thick?
    To adjust the drying of the paint, the distance between the model and the nozzle can be changed.

    Is it drying too fast and leaving orange peel? 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.
    Last edited by UNGLEWD; 05-25-2009 at 05:58 PM.

  5. #5
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    Quote Originally Posted by BC_4RUNNER View Post
    Is there one on cutting and glueing bodies?
    Their could be Greg...what did you have in mind?

  6. #6

    Thumbs up

    This is a great DIY for someone like me who's just easing back into the hobby. Great write up and I have to say I love your videos on painting polycarbonate bodies.

  7. #7
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    Thank you for putting this into a nice clear consise format. Your tutorials are a huge benefit.

  8. #8
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    Excellent thread. Thanks for sharing.

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