Thermoplastics 101: Worbla, Wonderflex and Thibra
Updated: Jan 26, 2022
Thermoplastics are a hot commodity in the cosplay community now a days. This plastic material becomes flexible and is easily manipulated at high temperatures. It's an easy way to make resilient, detailed armor and props. But it comes at a price, no really guys this method costs much more than EVA foam. The cost is enough to intimidate and dissuade many people from working with it. That being said, the saying, "You get what you pay for." applies heavily here.
Thermoplastic builds last much longer than an EVA foam armor piece and can withstand a lot more abuse on the con-floor. Personally I like to make gauntlets and boot pieces that are made of, or reinforced by, thermoplastics.
Brands of Thermoplastics
Worbla: One of the most popular and widely distributed thermoplastic on the market, they have many kinds of materials for various different uses. They sell thermoplastic in pellet and sheet form.
Wonderflex: Another well known name in Thermoplastics that is easily found at some of my favorite cosplay supply sites. Their products are mostly sold in sheets or rolls.
Thibra: a very malleable thermoplastic usually used for sculpting. Its very adhesive and it feels like you're sculpting with bubble gum. Products sold in sheets.
What's the Difference?
The differences between brands often come down to products available and the consistency or texture of those products. If you've looked into thermoplastics you may have run into one of the older debates about Worbla vs. Wonderflex. Both lines have a variety of products for different uses.
Finest Art: The first in their long line of thermoplastics. It is self adhesive and stretches well. Does have a slight texture. According to their site, it is favored for large builds.
Black Art and Pearly Art: Have slightly less stretch capability and are less adhesive than Finest art, this thermoplastic is used for detailing and has a smoother surface than finest art.
Mesh Art: This Thermoplastic has added strength with a structural plastic mesh and has the most adhesion out of all of their products.
FlameRed Art: This is a certified flame resistant thermoplastic. It is very similar to Finest Art in terms of properties, but has a notably smoother finish.
Kobracast: This is Worbla's thinnest and lightest thermoplastic. It is an open weave fabric that is almost gauze like. It is flexible and can be molded around extreme curves. It can be attached to fabric to help with complex fabric manipulation.
TranspArt: This material is a great substitute for PET and acrylic plastics. This material provides a resilient moldable translucent material that is shatter proof. It can be dyed and glued.
Wonderflex: A thermoplastic, containing it's own adhesive, that is reinforced by a fine web of fibers.
Wonderflex Pro: A thermoplastic, containing it's own adhesive, that is not reinforced by a fine web of fibers. It is more flexible than Wonderflex and can be sculpted into finer details.
Foss Shape: A felt like fabric that becomes rigid once heated with a fabric steamer. Can be sewn to itself or other fabrics as a hidden stiffener. Comes in three thicknesses (300, 400 and 600)
As you can see, Worbla has a an extensive inventory of sheet thermoplastics. They also have a line of pellet plastics which can be heated, dyed and pressed into molds. Wonderflex's Foss Shape products have a lot more thickness to them than Worbla's Kobracast, but is no less effective at helping with fabric manipulation.
Really the difference comes down to the individual. What your price range is, what you prefer to work with, and what you need for your build.
Handily the basic tools needed to work with these materials are things you may already have if you work with EVA foam.
Scissors or an exacto knife
Fabric Steamer (Foss Shape line only)
Silicone sculpting tools (Thibra for the most part)
Heat resistant gloves (Optional)
Thankfully it is that simple. As expensive as the material itself is it's remarkable easy to work with if you have the right tools and requires the least amount of safety gear to handle
Common Shaping and Sculpting Techniques
Heating: The most common way of heating your thermoplastic is by using a heat gun, however other methods include baking or boiling.
Molding or Sculpting: This is the process of using a silicone mold or press to shape or texture your thermoplastic. This method works best with thinner finer thermoplastics. simply heat your material until its at it's most pliable ant press it into your mold! once it's cooled it should pop out without a hitch.
Folding over Edges: The fold over method is a largely popular method as it uses less material. In this method you would use a thermoplastic to cover a premade base of EVA foam and simply fold any excess over the edges. this is an excellent way of reinforcing EVA foam builds.
Sandwiching: This method also relies on using EVA foam as a base. In this you would sandwich the prop, accessory or armor piece between two sheets of thermoplastic and carefully trim close to the objects edge. After that you can easily smooth the seam by smooshing it with your fingers or sanding it once it's cooled. This method is fantastic for props and accessories, despite requiring more material.
As stated previously, all thermoplastics have a different finish to them. one of the rougher finishes being Worbla's finest art. In order to really smooth out the surface before moving on with your build, it's highly recommended that you sand with a medium or fine grit sand paper before using a smoothing sealant.
Kinds of Sealants:
There are many options but I find these are the best:
Gesso: A flexible smoothing primer for thermoplastics. Is durable and can flex with motion.
Flexbond: A non toxic brush on sealant and Primer. Needs Multiple coats. Resists damage when bent or dropped.
Flexbond is found almost exclusively online, while Gesso can be found in local art supply stores. Both of these require multiple coats, to achieve the best smooth result, lightly sand after each coat dries.
Where Do I Get It?
Worbla and Wonderflex are the most widely distributed thermoplastics, to the point where you can find rolls of (overpriced) Worbla in Michaels. Here are some of the online shops I recommend you check for less expensive thermoplastic options.
After everything is said and done you will have a bunch of scrap pieces, I know you're probably thinking you could just toss them- But wait! You can recycle the scraps!
I save mine in a container for use on smaller projects. Most of Worbla's products can be reheated and molded together for sculpting or pressing into molds. There's even a way for you to flatten them out into small sheets using a pasta maker!
Check out the various ways you can use your scraps here.