If you’ve spent time on the RPF, or looked through our Ultimate Smoothing Guide, you may have heard of Flexbond. It’s a Rosco product that is meant to be used as a glue for foam and other materials, designed for stage and screen use.

Cosplayers, of course, always find new uses for things – and for those who could get their hands on Flexbond it’s become one of the preferred primers for sealing all types of foam before painting. A few years ago we had several customers use it for Worbla – and when we saw the results we knew we had to make it accessible to everyone.

Okay, so what’s the big deal?

Flexbond has a few specific points that make it really, really handy to use for quick armor priming to get a very smooth finish without too much time or labor.

  • Flexbond has a high surface tension, so brush strokes even out easier than other coatings, giving a smoother surface.
  • Flexbond is meant to be a glue, so it ‘grips’ itself as you add layers – minimizing drips and runs when applied in thin layers, while still drying without a tacky finish.
  • Flexbond is water soluble, so if you do have drips or runs, they’re easy to fix without having to repair a large area.
  • Flexbond dries clear fast – faster than any other brush-on primer.
  • Flexbond is non-toxic, and can be used in small spaces – it doesn’t smell bad and won’t poison you with fumes.
  • Flexbond, like the name suggests, remains flexible. Pieces can be flexed and struck without chipping or cracking. Toss your armor in your luggage for airport security or build designs that flex on and off without worrying about your finish or last minute touch-ups.
  • Flexbond will coat thermoplastics and foam with the same finish, meaning that you can coat pieces at the same time and paint them without distinct surface differences.
  • Flexbond can smooth Worbla’s Finest Art to a smooth, paintable finish in as little as 3 coats, and Black Art in 2, though your mileage (and personal preference) may vary.

Flexbond comparison2

We aren’t saying Flexbond is the best primer ever – there are so many ways you can prime that saying one way is best is just silly! We have a whole section dedicated to the different methods people have shared with us! We are saying it’s one of the best options we’ve found – and if you ask for our suggestion for Worbla, Flexbond is going to be at the top of the list!

What’s the big deal?

Flexbond was just not the easiest thing to buy originally. Before we managed to partner with Rosco it only came in one and five gallon containers and Flexbond expires after about 24 months. You can still use it after it’s expired – but it loses some of the non-drip/run quality and gets a lot more viscous. Stage shops might carry it, if you’re lucky to have one near you – but otherwise you’re buying online and the shipping can be really expensive – if you can find a place that ships to you – nevermind buying a gallon or five at a time can be a big investment when it may go bad before you’ve used it up! A little really goes a long, long way. So partnering with Rosco allows us to offer 16oz bottles that are enough for almost any large scale project, and we do also offer gallon bottles with easy shipping worldwide.

What else can you use it for?
The original Flexbond webpage says it best:

Use FlexBond to adhere fabrics to fabrics, fabrics to wood, foam to wood or fabric and many other combinations of materials common in scene shops. Rosco FlexBond provides an excellent coating over Ethafoam™ (semi rigid packing foam) that allows this notoriously difficult foam to be painted with ease. With its super adhesion, Rosco FlexBond can be used to laminate blocks of foam together. It can be thinned with water, tinted with colorants or Rosco Paints, or used as an additive to give other coatings like plaster or clay added flexibility.


Right. So. Let’s see it in action?

A few examples in use:
Flexbond comparison2
Above: 2 coats of Flexbond on Black Worbla.

Above: 3 Coats of Flexbond on Worbla’s Finest Art (brown)




In comparison to Other Primers:

From left to right: Mod Podge, Gesso, Flexbond, PVA (white) glue, Carpenter's (wood) Glue. 2 coats each.
From left to right: Mod Podge, Gesso, Flexbond, PVA (white) glue, Carpenter’s (wood) Glue. 2 coats each.

Flexbond needs less coats to achieve a smoother surface. The more coats of any primer you add, the better the result. More than that, Flexbond is very resistant to damage. I took a hammer to each of the above bracelets (after adding several more coats to the PVA and Wood Glue options so that they had the usual expected smoothness.)

Flexbond. Hammer marks somewhat visible if you squint you can see the 'c' shape.
Flexbond. Hammer marks somewhat visible if you squint you can see the ‘c’ shape.
Carpenter's Glue cracked the worst at the sides where the worbla bent. Mod Podge tore away from the surface.
Carpenter’s Glue cracked the worst at the sides where the worbla bent. Mod Podge tore away from the surface.
Gesso is almost totally intact - I managed to chip it in one tiny spot. The PVA glue created a 'skin' that cracked and would lift away from the worbla when twisted.
Gesso is almost totally intact – I managed to chip it in one tiny spot. The PVA glue created a ‘skin’ that cracked and would lift away from the worbla when twisted.
 (I forgot to put them back in original order whoops) From left to right: Gesso, PVA (white) glue, Carpenter's Glue, Mod Podge, Flexbond.
(I forgot to put them back in original order whoops)
From left to right: Gesso, PVA (white) glue, Carpenter’s Glue, Mod Podge, Flexbond.

Of course, you’re not likely to take a hammer to your costume pieces! But travel, luggage handling, crowded convention spaces – or just dropping a prop or piece of armor – can all mean a headache of patching and repainting, with standard primers.

Important Note about ‘Wood Glue’
Wood glue is one of the most commonly referenced primers for Worbla – Kamui Cosplay talks about it in her books and videos, and many cosplayers have been using it for years. The problem? When I spoke to Kamui while in Germany, I discovered that the wood glue I and my friends were using – yellow, waterproof ‘Wood Glue’ – made of aliphatic resin emulsion – was not what she used – she was using PVA (polyvinyl acetate) white glue. Depending on where you live and where you purchase from, PVA glue can be sold as Wood Glue, Craft Glue, Hobbyist Glue…
Both forms of glue work to prime Worbla’s Finest Art and Mesh Art, but Carpenter’s Glue dries very hard (and brittle) and waterproof and can be sanded smooth, while PVA glue remains water soluble and more flexible, but often doesn’t ‘bond’ to Black Worbla, instead making a ‘skin’ over the surface. Keep this in mind when someone refers to ‘wood glue’ if their results are different than yours!

Age and Travel…
If you did check out the Ultimate Smoothing Guide, you’ll remember the bracers I made for all those tests last year.

(Expired) Flexbond, a year later....
(Expired) Flexbond, a year later….
Still flexible as always, no cracks or damage.
Still flexible as always, no cracks or damage.
Carpenter's (wood) Glue, a year later.
Carpenter’s (wood) Glue, a year later.

The above pieces were stored in the same locations, taken to the same conventions, thrown around in the same luggage containers by the same TSA agents.

Also worth noting, the Flexbond I used for my initial tests was pretty expired, and as a result created a more ‘rippled’ effect. As I’d made a bunch of bracers to test against, I applied my new Flexbond to a bracer for comparison.

3 Coats of (not expired) Flexbond
3 Coats of (not expired) Flexbond
Click to enlarge. Common brush-on primers compared on Finest Art and Black Art.
Click to enlarge. Common brush-on primers compared on Finest Art and Black Art.

In (not so short):

Flexbond does more in less, without requiring sanding and while remaining flexible and durable.
Flexbond can be used standalone, or combined with other products, and the findings in the Smoothing Guide can be used as a much more comprehensive breakdown/comparison of Flexbond and other Primers. In the next few weeks I’ll be creating some tutorials that show both using Flexbond on its own, as well as mixing it with other primers to cut down your priming time further or to get the smoothest finish possible.

That was too much text. Recap?

Need it to be smooth fast and can’t use spraypaint primer? Use Flexbond
Need to use a primer that can be safe indoors/around kids and pets/won’t smell? Use Flexbond.
Need a primer that will give you a smooth finish in less coats and without needing to sand? Flexbond.
Need something that will keep your paint from chipping and flaking off under stress? Flexbond.
Need a last minute topcoat and can’t spraypaint? Flexbond works as a semi-gloss topcoat too.


When purchased with any thermoplastic at Cosplaysupplies.com, the 16oz bottles of Flexbond have free shipping! The one gallon bottles will have separate shipping cost calculated based on location.

How to use Flexbond/Tips and Tricks:

We now have a page dedicated to Flexbond information and tutorials here!
Here are your basics:

  • Make sure your surface is clean and free of dust
  • Use a medium to large brush compared to your project, or a sponge brush, to help coat the surface evenly and minimize brush strokes.
  • Use a somewhat damp brush to apply Flexbond for the smoothest finish.
  • Apply thin layers, being careful not to apply so much that it will want to drip and run.
  • Resist the urge to go over and over an area – Flexbond sets up quickly enough you can end up having very noticeable brush marks.
  • Allow layers to dry fully (they will be clear) before applying the next.
  • Mistakes, brush strokes, drips and runs can be carefully smoothed with a damp finger or brush. Flexbond will reactivate with water, making for easy cleanup.

Other things to note:

  • Flexbond isn’t recommended for prolonged exposure to skin, so wear gloves if you plan on being really really messy.
  • The first layer of Flexbond dries faster than subsequent layers.
  • Flexbond also makes an excellent glue for Paper Mache when you need some durability and flexibility, and it has been used watered down for wig styling as well.
  • Flexbond can be watered down, but keep in mind that if thinned too much and applied to a plastic or foam surface, you may get ‘bubbles’ or ‘breaks’ in the surface tension. Experiment first before applying to a large project.
  • Flexbond can be mixed with paint or tint, so you can save time by mixing your base color in your Flexbond for your later layers.
  • Flexbond can be airbrushed, for an excellent finish. From one of our customers: It speeds up things to carefully hand paint the first few layers and then go in with about a 1/3 FB to 2/3 distilled water mix at around 30 psi
  • Also: Your Flexbond will have a Bottled On Date (at the bottom). Remember that it will start to lose its consistency after 24 months.

Okay, wait, but the price?
Bottles will be $31, with free shipping when purchased in any thermoplastic order on Cosplaysupplies.com our official online retail partner.
One gallon bottles will be $81 and shipping will be additional and based on region. Prices may vary at other local or online retailers.
The one gallon bottle is obviously much more product than the 16oz holds – 8 times the size – but isn’t 8 times the price. This is because we had to have the smaller bottles decanted professionally, as Rosco wants to ensure their product quality, and so it could not be done in-house. Flexbond can absolutely be decanted into airtight containers yourself – so consider if you have a group of friends who may want to split a larger bottle to save costs. Just make sure you all note the original bottled by date, and that the containers you use are airtight.

But I like my current priming method.
Everyone has their own way – and we showcase half a dozen methods so far in our tutorials! If your method isn’t on our list, let us know! We think Flexbond is one of the best ways, but it isn’t the only way by any means!

Will Flexbond work on _______
Short answer: Almost certainly.
Longer Answer: Flexbond has been tested on: basically every possible foam out there, Wonderflex, Worbla’s Black Art, Worbla’s Finest Art, Worbla’s Mesh Art, Worbla’s Deco Art/Friendly Plastic, Worbla’s TranspArt, Thibra, wig fiber, paper/newsprint/cardstock, felt, fabric, air dry and bakeable/hard clay. The list is probably even longer.

Painting and Finishing
We haven’t found a finish that can’t be applied over Flexbond, and Flexbond can be mixed with paint to tint it. You can mix 50/50 with acrylic paint to act as a paint primer, for example. You can use it as a base to build up a flexible surface and then use high build auto body primer, or other spray finishes, to help cut time down on creating the smoothest finish possible.



More questions? Have you used Flexbond for your own Worbla and have images or other tips and tricks to show? Email Lenore@worbla.com with them!