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How to smooth out Worbla/Wonderflex (with Gesso)

Thermoplastic sheets like Wonderflex and Worbla have a textured surface which can be rather annoying if you are planning to make something with a more smooth and shiny finish to it. In this tutorial, I will show you how to mask the bumpy texture .



  1. A paintbrush
  2. Gesso: I don’t think the brand really matters, but the thicker it is the better. I’ve been using Liquitex Gesso.
  3. Various grits of sandpaper: I use three different kinds of grit, 100, 220, and 400.



I’m going to be using some armor parts that I test-built based off of a character named Shun from Saint Seiya. It is made out of Wonderflex with craft foam inside of it. I am done building it and now I just need to paint it! NOT. Before painting anything, I have to apply multiple of layers of gesso on it if I want this armor to look smooth.

To do that, I applied a layer of gesso onto the armor. Each time it dried, I painted another layer of gesso. I repeated this process many, many times until I knew it was thick enough to withstand a whole lotta sanding that I’m about to do.

A good way to tell if you don’t have enough layers is to take a pen/marker and doodle something on the thermoplastic before applying gesso to it. If you still see your doodles through the gesso then it most likely means you don’t have enough layers. So keep on applying gesso until there are no traces of your pen markings.


Here’s what it looks like after it’s been gesso’d up but hasn’t been sanded yet. Pretty icky right? TO THE SAND PAPER WE GO!

I first started with 100 grit to get rid of the obvious bumps and ridges that the gesso made. I did this for about 5-10 minutes. I didn’t want to take too long because 100 grit is pretty rough so I didn’t want to over-do it.


Next, I moved up to 220 grit to smoothen out the surface. I did this for about 20 minutes.


Finally, I used 400 grit to smoothen out the surface even more. I did this for about 30 minutes. The time it takes to sand the armor greatly depends how smooth you want it to be and how patient you are.

After I was done with the sanding, I sprayed a coat of primer on it. When that dried, I used a glossy pink paint spray for the base color of the armor.

gessowonderflex bumpywondeflex

Applying layers upon layers of gesso and then sanding it for an hour doesn’t sound like fun but trust me, the result is absolutely worth it. Next, I will write a tutorial on how to paint the armor!


Published inTutorials


  1. […] up to help cure the slightly wavy edges. Check out this tutorial if you haven't already seen it. How to give your Wonderflex/Worbla a smoother texture | HONEY.BOBA Reply with […]

  2. How long did you wait between layers of gesso and between the final layer and sanding? I have that same brand and it says 24 hours but it sounds like that might be for canvas rather than over Worbla. Any advice?

    • Tiff Tiff

      To apply additional layers, on a hot summer day, I wait about 5-10 minutes each time. Normal/cold temperatures, I’d have to wait about every 30-45 minutes.

      To sand, I wait about an hour during the summer and 2-3 hours when it’s not hot.

      If you have the same brand, you might be ok. You can simply test it out and see how long it’ll dry.

      • Enveous Enveous

        Thanks so much! How many layers would you estimate were on these?

  3. Misako Katsumi Misako Katsumi

    Well that looks amazingly smooth. It does sound like a pain in the butt but it is definitely worth it after seeing those results ^u^ I want the same results for my project. Question though. What brand of primer and paint spray did you use?

    • Tiff Tiff

      It can definitely be a pain in the butt, but you just have to be really patient. Every time I put a layer of gesso, I’m usually watching something on Netflix so that the process doesn’t seem tedious lol. But yeah, the end result is totally worth it.

      Generally, it is more efficient to use wood glue instead of gesso, which I will be posting a tutorial for that soon! 🙂

  4. Seraph Seraph

    How well does the gesso stand up to bending and abuse? Concerned over flaking. Also, would you use the same technique for wonderflex as for worbla?

    My current project is a suit of costume armor that will be used in a LARP, so I’m trying to make it on the beefy side using 3/8″ ABS foam covered in wonderflex. I’ve been using plasti-dip to fill in small imperfections, but I don’t get nearly the level of smoothness in your pictures because it doesn’t take sanding.

    • Tiff Tiff

      Hi Seraph!

      It stands up very well actually. I’ve had it cracked before but it doesn’t happen often and when it does, the crack tends to be very small and easy to fix.

      It also helps a lot if you use a finishing coat so that it would protect the paint job.

  5. cydney cydney

    What’s the difference of using gesso vs mod podge? And can you sand mod podge down like you’ve done with Gesso here to get smooth finish? Have you tried mod podge plastidip combo? Would you sand do podge with plastidip?

    • Tiff Tiff

      Gesso is like a really thick acrylic paint that you can sand.

      Mod Podge is like a really thick elmers glue that you can NOT sand.

      Yes, I have tried mod podge and plastidip combo, but only on EVA foam.

      I most likely would not sand if I use mod podge and pastidip.

      Hope that answers all of your questions! ^_^

      • marrog marrog

        Hi there! Am reading all the tutorials out there with some interest as I’ve been working with Worbla for the first time and wanted to do some quick’n’dirty smoothing (didn’t have to be flawless, just a bit less grainy). I’m interested that you’ve said that you can’t sand mod podge. My experience having just used it for a pauldron was that it sanded fine provided I didn’t use a harsh grit. With about, Idunno, a half dozen layers of mp, I sanded with a fine, soft paper, and it was fine, though I knew that if I put a foot wrong and went through the bottom layer I’d be screwed so I had to be very careful! Here’s how it came out:
        As you can see, far from glassy smooth – clearly gesso is the way to go for that – but for my purposes it was a very quick and easy way to get what I needed.

        • Tiff Tiff

          Hi Marrog! Apologies for not getting back to you sooner as I was in crunch mode for BlizzCon. Now that that’s over, thank you so much for sharing that! I definitely was wrong and your pauldron came out to be awesome. Thanks again for the information, I appreciate it. 🙂

      • marrog marrog

        Hey, totally cool, was just checking in while doing my thing 🙂

        I think in retrospect if I was sanding with fresh paper I’d probably rip the layer MP, reckon I got lucky by using one of those soft foam pads you get, and the grit on it was pretty well-used and soft.

        Having finished said costume since I think if I was doing it again I’d wet sand, though the method I used for the pauldron did work okay. I wet sanded the belt buckle I did and that worked out pretty well.

        The finished pauldron:

        The finished belt detail, made with Worbla scraps, which I wet sanded over maybe three or four layers of mod podge (still pretty lazy!):

  6. Merethe Merethe

    Hi 🙂
    You say in a comment that wood glue is better than gesso. Is the process the same? I have wood glue, so I would prefer to use that, but I thought you couldn’t sand it.

  7. kass kass

    after smoothing and spray painting how do i paint it?

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