How to use Silly Putty for masking and painting Gunpla

This HG Z’gok Experiment gets its flashy red accents from Silly Putty masking.

We all know that Gunpla painting comes out better the more prep you do ahead of time, but it’s tedious to tape up everything before you paint it—and it sucks when the paint bleeds under the tape anyway! Now, contributor Megaplamo is sharing another solution with us. Read on for his Silly Putty strategy.


I don’t trust anyone who says they enjoy masking—the process of partially covering your Gunpla with masking tape before you paint.

However, there are many times when masking is a necessary evil. When you’re painting a larger surface on an HG kit or removing seam lines, you can’t simply free-paint by hand and hope for the best. Additionally, while masking tape is useful and even easy to apply for flat areas that require straight lines, round or organic shapes require a lot of time and work and can be quite frustrating to mask.

What if I told you that there was another option? Enter Silly Putty.

You can find Silly Putty almost anywhere, from the hobby shop to the grocery store to Amazon. Many of us grew up with it and are pretty familiar with its properties. It’s easy to mold and sculpt, you can stretch it or snap it, and when left alone it will conform to the shape of the container that you put it in. Plus, since silly putty is oil-based, you don’t have to worry about it sticking and harming acrylic or lacquer-based paint.

In this tutorial I will be working on pieces from the HG Z’gok Experiment, an older kit that requires quite a bit of masking. Follow along as I use the Silly Putty masking technique on a concave booster so that the outside of the cone will be Tamiya Dark Grey and the inside of the cone will be Vallejo Mecha Red.

First, hold your piece in an alligator clip on a stick and prime it. Find out how to make your own alligator clip Gunpla tools here.

For this kit, I used Vallejo Mecha Primer White. It’s much tougher than the original Vallejo surface primer and will create a good surface for the other paints to adhere. This primer is water-based, so I waited 24 hours for it to fully cure for maximum durability since I will be using the alcohol-based Tamiya in the next step.

Next, spray the Vallejo Mecha Red on the inside of the cone. The key is to lay down a good even coat but to keep it accurate so as to avoid unnecessary overspray. Wait for the paint to dry and move on to the next step.

When the paint is fully dry, take a piece of Silly Putty and eyeball the size of the area you would like to cover. I like to start off with a little bit more than I need and then snap excess pieces off of the putty until I have the right size. Next, place the putty in the cone and then press it so that it fills or fully covers the area that you want masked.

Spray your second color. In this example, my second color (Tamiya Dark Grey) is darker than my base color. If in your case, the second color is lighter and or thinner than your base color, then I recommend spraying some white or grey primer before adding the second color so that the base doesn’t show through.

Once the paint is dry, carefully remove the Silly Putty with a toothpick. And there you have it!

A few more tips:

  • Be sure to paint very soon after applying the Silly Putty because it will shift over time. In other words, don’t putty your piece, leave it overnight, and expect it to cover the same amount of space the following morning. If this does occur, I recommend touching up any imperfections with a paintbrush.
  • For best results use an airbrush or a paintbrush. I don’t recommend using a rattle can when working with Silly Putty since some aerosols have unpredictable solvents and may affect the putty in a negative way.

Here are a few other examples of what I masked on this kit with Silly Putty:

As you can see, the possibilities are endless and you can get pretty creative as you go. I hope you add Silly Putty to your arsenal of hobby tools!


Megaplamo has been building plastic models since 2001. When not building he plays the guitar, bikes, and travels. He lives near the Gulf Coast of Alabama where he and his wife are teaching their two cats to become productive members of society. You can follow @megaplamo on Instagram for current projects, completed projects, and Gunpla building tips.

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