As the engineering behind Gunpla becomes more and more advanced, so do the inner workings of our favorite bipedal war machines. For years, Perfect Grade and Master Grade kits have included intricate inner frames. That detail has now been extended to the Real Grade line and nearly perfected in kits like the MG Sinanju. Because of all the moving parts, some people might find the task of painting an inner frame quite daunting! In actuality, all it takes is planning and patience. Read on to learn more!
First things first, you're going to need an airbrush. I use an Iwata HP-CH for all of my painting needs, and would highly recommend it. This brush has a .3 mm nozzle and can handle everything from priming to detail work.
For large scale processes like priming a ton of pieces, I like to mix up a jar beforehand. It's much easier to dip a pipette in premixed primer than it is to mix it over and over. On the right is Mr. Surfacer 1200, and behind that you can see Mr. Leveling Thinner. These are being mixed together in the other jar until I've reached the right viscosity.
The usual recommendation is that your paint should be the consistency of milk. When you feel like you've got a good batch try test spraying some paper. If it's too thick your paint will sputter and spiderweb; too thin and it will run and disperse as you spray. Play with the mix until it sprays evenly like in the above picture. I spray primer at 18-20 PSI.
When you're satisfied with your mixture, grab a skewer and get to work.
When I prime, I give each piece a light coat of primer, followed by a thicker coat. The first coat gives the following coat more to grab onto and improves the paint's adhesion to the plastic. This picture is after the light coat.
And here is the same piece after the second coat. It's important to achieve good coverage because you're essentially laying the groundwork for the rest of your paint job.
When all your pieces have been primed, it's wise to place them in a good location to dry/cure. I put mine inside a polyurethane storage bin in order to prevent any dust from settling on them. Although I would advise letting each layer (primer, paint, clear coat, etc.) cure overnight, I've painted an entire kit, start to finish, in one day with no adverse effects.
When painting my frames I've found that it's best to use a few different colors of metallic paint to give each limb the appearance of an actual piece of machinery; how often have you seen mechanical workings that are completely monotone? I really like using Alclad paints because they're pre-thinned and do not require a clear coat, so for this build I'll be using Alclad exclusively. I covered using regular and high shine Alclad in my metallic paint tutorial, so refer to this for a walkthrough on using Alclad:
Here are the four different metallics I chose to paint the legs. From left to right: Magnesium, Steel, Duraluminum, and Copper. Although not pictured here, I also used stainless steel to paint the ball joint on the top of the leg, and what I can only refer to as the tube holder on the back of the leg. Stainless steel is a high shine finish so I like to use it on rounded objects for the extra reflectivity.
I also wanted to include an exploded view of the leg, before I put it together. This picture should give you an idea of how to vary your colors throughout the frame. It is important, however, to think about what will be showing when the build is complete. You don't want your kit's ankles to be gold, while the elbows are silver. Or maybe you do, in which case, disregard that last bit.
Once assembled, it ends up looking like this. Pretty snazzy, if I do say so myself! Remember that you should plan ahead during your assembly stage. I usually have every color in mind before I even begin to prime.
A couple more close up shots so that the color separation is really evident. You can also see the stainless steel ball joints and how they shine compared to the regular Alclad. Note: the pistons were not painted, they come cast in chrome.
The next walkthrough will cover painting the outer armor, for which I'll be using Mr. Color paints and thinner. Hopefully this section was helpful, and thanks for reading! Questions and comments always welcome below.