It’s useful, it’s versatile, it’s everyone’s favorite product…foam!
Let me acknowledge that foam can be a very dangerous material when not treated with care and respect. No respirator cartridge can filter out all of the bad stuff that comes out of foam when you break it down chemically.
Acetone and hot knives were the processes fervently taught when I was first learning about foam carving. Yes, you can indeed get some cool textures if you burn or melt the foam, but just don’t do it. The cost to your health and the environment is too great. I am not a scientist but I listen to the experts. When in doubt, just listen to Monona Rossol.
Now that’s been covered, onward!
So you’re at the start of your foam carving project, yay! You have the designs in hand with a juicy foam carving project in the works. Unfortunately, renderings and elevations don’t always provide all of the information you’re gonna need. Often additional research images are required. If clear examples aren’t provided for you, find some of your own and chat with your charge or designer to make sure you’re on the same page.
So much about foam carving is learning as you go. You will make mistakes and then get to fix them. Sometimes those mistakes lead to a cool texture or process that you get to use on a later project. Although every project is unique, there is a basic path:
- Start with a structure
- Apply foam to the structure
- Sculpt foam
- Repeat steps 2 and 3 until satisfied
- Protect and finish your project as needed
Have productive conversations with the folks engineering and building the base structure from day one. Advocate for the project and ask questions because mindful construction can save you time and money.
Foam has infinite potential. I’ve carved trees, dimensional portals, and what feels like every variety of stonework. Before anything gets created you’ve got to decide what kind of foam you want to use.
Types of Foam
There are a couple of kinds of foam available, you can choose between extruded polystyrene (pink foam board) or expanded polystyrene (white bead foam) for your main carving medium. Extruded is easier to find in big-box construction stores whereas you have to order blocks or sheets of the bead foam from a vendor.
The white bead foam also comes in varieties of pressure. The higher the pound per square inch, the more densely packed the beads are. If you are looking for something with a very smooth final finish you’ll want to go with a higher pound pressure.
I encourage you to be thrifty, feel free to save and reuse the denser pieces of foam that come along with any of your shipping.
The third type of foam you can use is Great Stuff. It’s foam in a can and it makes the job much easier. It’s a wonderful way to fill gaps or voids in your work. I’ve used it as an adhesive and as a visual texture. It’s a super handy product which of course means it’s toxic. While the foam is actively curing, it’s also off-gassing fumes which are not good for humans. Make sure you’re in a well-ventilated space that you can leave for a while after you spray your foam.
You should check out the Great Stuff Pro line if you have to spray 8 or more cans. The pro cans are bigger and there’s a gun they screw onto which is a huge relief on your hands.
As you add foam to your structure there are a couple of ways to get it to stick together.
You can laminate your pieces together with 3M Fastbond Contact Adhesive. Foam rollers work the best for application on foam. This option is great if you have a lot of flat surface area to bond to a more flat surface area.
If your shapes are random and have a less than flat surface area, I like to use Loctite PL 300 Foamboard Adhesive. This product needs pressure and time to cure. The instructions say you get a full cure in 7 days but I usually leave it for 8-12 hours and then the area is carvable. If you can, evenly distribute weight over the surface you’re bonding. When working more vertical than horizontal grab yourself some huge washers and 4” screws and tack your pieces in place. If possible, throw a ratchet strap around the area, you can use towels to protect your project from the straps and sheet goods to disperse the ratcheted pressure if you’re working with awkward shapes.
For the strange or inconvenient placements or when you’re fighting gravity, your best option is bamboo skewers, painter’s tape, and Great Stuff. Place your foam pieces in place with the bamboo skewers, then tape them in place. Next, you’ll fill in the gaps and cracks with Great Stuff and let it cure. Pull the skewers before you start carving!
Let’s prep the space
Foam carving creates a lot of clean-up. Plan to clean as you go, if you don’t there’s a good chance you could lose your smaller tools in the particulate. Grab a cart or a 5-gallon bucket for all of the gear to keep it separated from the soon-to-be mess. Make a trash plan. Decide what size foam pieces you want to save to potentially reuse. Then consider what you want to offer up to other folks and what’s headed to the dumpster.
It’s important to think sustainably about toxic materials. Budgets are tighter than ever and the environment is in crisis. If you can’t reuse it, hook up with a regional sustainability group, like the Chicago Green Theatre Alliance, or get in touch with your local theatre network. Foam particulate might be a great textural additive that can be used on another project, don’t let good materials go to waste.
Foam gets and stays everywhere. Dress with that in mind. Jumpsuits are the easiest way to keep foam contained-ish. Most often I opt for long sleeves and long pants. For PPE, be sure to wear goggles or glasses that wrap around and seal. Keep your hair up and covered. I wear a respirator with organic vapor cartridges, N95 filters, and over-ear hearing protection. After I’m done carving, I get rid of the particulate with a brush and vacuum. Even then, some will still follow you around.
Permanent markers, sandpaper, and snap-off blades are kit staples. Japanese Ryoba pull saws are my go-to for large-scale hand carving. Feel free to use all sorts of cutting implements, just be sure they are sharpened. Nothing will cut you quicker than a dull knife.
You get to create your tools too! The hardware store won’t always have what you need. For instance, I needed something to help me make a pitted surface faster. I was inspired to make a tool that scrapes, delightfully picks the foam, and incidentally looks like the devil’s hairbrush. Additionally, check out tools from other industries like nail salons and dentistry you might catch some inspiration.
Power tools make quick work of foam. If you’re working with bead foam, the denser it is the more effort it will take to carve it. You can bust through the extruded foam with less effort. Particulate foam can get very small and get into your tool’s interior and potentially melt. Protect your motor’s air intake area with flexible window screen material and gaff tape.
It’s important to note that with grinders friction is doing the work. If you focus on one spot for too long you will start to melt your foam which we want to avoid. Use an easy hand as you work with power tools. Please avoid learning that it’s ‘easier to cut more away than it is to add it back’ the hard way.
Protect and Coat
There are a bunch of ways, each at different price points, for you to protect and seal your foam.
Smooth-On makes so many different products that coat and protect foam projects. They also have helpful videos and articles on their site and great customer service. I’ve only been able to use these products on long-term, very audience-friendly, larger budget projects. If you’re working in the world of theatre, check this line of products out if your foam project needs to be indestructible, for anything less these options might be overkill.
Habitat Cast N Coat
I was looking for an oil-slicked, oozy texture that was audience-proof. and saw an opportunity to use Habitat Cast N Coat. It’s a brushable 2-part epoxy that you can tint. Mixing to proportion gives you a pourable syrupy texture which was exactly what I needed, but you can make it more viscous with a thickening powder. Be sure your room temperature can stay consistently warm for at least 16 hours so you can get a good cure.
EZ Spray Jr.
Using the EZ Spray Jr. system was an easy, straightforward, but initially intimidating process. I used the sprayable rigid foam to protect and seal giant foam boulders. Make sure you read the manual on this one and utilize the correct personal protective equipment (PPE) for the products you’re using.
Jaxsan 600 comes in three different grades, trowel, brush, and sprayable. You can purchase it from the company in white, light grey, aluminum grey, tan, and black but it’s also easy to tint your own. This product is durable and waterproof. Feel free to add sawdust, cork, particulate foam, or any other favorite textural additives for a little bit of spice. Bonus, they have stellar customer service and are great to work with. I love to use Jaxsan but I couldn’t use it on my lower budget projects because it can get pricey. Also please note, if you’re working in a place where it gets below freezing on the regular in winter, shipping can get dicey. This stuff doesn’t bounce back from even slightly freezing so it’s not something you want to get shipped during a deep freeze.
Elastomeric Roof Coating
You can get a generic version of Jaxsan at the big box stores. This product has a thinner, more brushable viscosity and is much easier on your budget. If you’re missing that trowelable texture, add a little joint compound to give this product more body.
A big part of protecting your foam is making it resilient to the wear and tear of the production. Dutchmaning your seams is a great way to help protect your sculpt. To do this, reinforce the areas that will get the most wear and tear by brushing out your elastomeric, place muslin or cheesecloth and add a layer of elastomeric on top. This is a great way to use up your fabric scraps.
There are so many other ways to seal and protect your foam that I haven’t mentioned, check out the Guild of Scenic Artist Facebook page for what others in our industry suggest too!
Before your project can take its final coat of paint you have to prime it. Foam can be a fickle mistress and paint adhesion can be tricky. If you used elastomeric, it takes most primers pretty well. If you have raw foam use a layer of Plaster-Weld before your prime or use applied texture. Do samples and then give them a road test to check the resilience of your final look. One of the worst feelings is seeing your final paint job peel off the raw construction material.
No foam carving project is exactly like another, each one will have its unique challenges and requirements. It takes patience and an open mind. Keep track of what works and what doesn’t. Reach out to people when you need help or advice. I hope you have fun on your next project!
Check out these other great articles from Steph Charaska on the Scenic Route Blog!