Using Worbla to Reinforce a Foam Breastplate

Sometimes you make a piece or project and it turns out that you need it to be sturdier than you planned. Or maybe you specifically need foam to be on the outside of a build, for your LARP rules, or for detailing purposes. Or maybe you’re just trying to use as little Worbla on a build as possible because you’re on a budget!

One way you can use Worbla that we’ve started to see more and more of is as a backing for foam, instead of covering it! We want to walk you through the process and when and why and how you’d use Worbla that way!

This breastplate was made using one of Kamui’s paterns, out of 1/4″ L200 foam. It’s lightweight and flexible, but a little too flexible: if you’re wearing a piece like this, it is going to want to crease at your middle where you bend, that’s just the nature of foam!

We made this chestplate to be a front only: it will be covered by a jacket over the back, so this keeps the heat of wearing it down: foam doesn’t breathe after all! We reinforced the neck so that area wouldn’t warp, and the front chest, while allowing the sides to be flexible so we can put it on various model sizes.

Breastplate assembled from Kamui’s pattern. Be kind about those gaps, this was our first attempt at a multi-piece foam build!
We smoothed the gaps with Kwick-Seal putty and sanded everything with a Dremel. We found the sanding bits were too rough for the lower density foam, but the grinding bits worked perfectly to smooth and shape.
The inside of our breastplate
We cut some Worbla’s Finest Art slightly smaller than the piece we wanted to cover
Worbla was heated and pressed to the foam. We used Finest Art because it has the best adhesion out of our standard products for this sort of work. We also added the collar piece, and a bit along the center/collarbone to reinforce that area. It isn’t pretty, but it doesn’t have to be! We’re using scraps here after all.
This area needed 2 layers of Worbla instead of 1 just to ensure that things didn’t flex when we didn’t want them to.
You can see how we folded the collar over here, giving us a nice clean edge that would hold its shape no matter what.
We sanded the Worbla here with the Dremel to help speed up the priming process.

The end result is a solid breastplate that can be worn without worrying about creasing at our flex points, while staying lightweight and inexpensive – great for a quick build.

Here you can see the complete piece with the first coat of Flexbond to prime it. The Worbla down the centre also allowed us to heat and curve the panel under the breast to hold that shape with ease. Without the Worbla, this foam is soft enough it won’t support it’s weight against gravity for long, but here it has no issues.


We had some fun experimenting with new paint for this project!

Deco Art sent us some paints to test that we used for the base of this build! Their Matte Black, Black Premium Acrylic, and Americana Decor in Soft Silver (and Premium Acrylic in red, not pictured)
Folk Art’s color shift series! We used the Orange Flash on its own, and Blue Flash laid over our Jacquard blues.
We used Jacquard for our blues, their Sneaker Series Neo Opaque, and Lumiere series. Sharpie oil-based markers in white and black helped us with the last details!
Step one was laying the base coats down, using Deco Art black and silver, and the Folk Art orange. As you can see the orange goes on really patchy.
Closeup of the orange after 3-4 coats. It’s just too thin to stand on its own against a smooth black, and would have absolutely benefited from being layered over a similar base color. Lesson learned for next time!
We used painters tape to give us a clean line for the red and orange, and started filling in the red with Deco Art Acrylics.
Painter’s tape laid down to give us clean edges on the underbust detail
Painting in the underbust
You can see the original base blue we used, and the skull outline done using a chalk marker. These are great for sketching as you can erase mistakes with a wet cloth. This was sketch one, which was redone to be smaller and at an angle later.
Our skull painted with white Deco Art acrylics, the black detailing done with black acrylic and touched up with a black, oil-based sharpie. The blue seemed too bright, so we went over it again with a darker shade from Jacquard and then the Folk Art interference paints. We also did paint the black with the matte at this point – it has a great finish!
Here you can see the smooth silver of the Worbla neck (only one coat of primer was needed because this was pre-sanded), and some of the detailing we did with a stipple sponge

Final Project

Chestplate and matching bracer with finished paint
Inside of the plate – the Worbla means it can hold itself up without warping!

There you have it! You can use this technique at the start of your build, or add Worbla when you’ve completed and already worn something, if you discover it needs to be reinforced!