Frequently Asked Questions about Foam

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Two Part Polyurethane
Builders often use two-part expanding polyurethane foam, such as Great Stuff, and commonly use a hot wire to clean up the edges. However, not all of these foams can be cut with heat, and ALL of them emit toxic fumes when cut with heat. It is essential to use respirators and work in well-ventilated areas.

Plastics
Some plastics can be cut with a hot wire or hot knife, but this process is slow and the fumes produced may be toxic. Coroplast can be cut, although slowly, using a hot wire or hot knife.

Many people prefer to use hot wire tools to cut nylon and polyethylene rope as it singes and seals the ends.

If you're uncertain whether a hot wire tool will cut the foam you intend to use, please consult with us and the foam manufacturer prior to making a purchase.

Q: Are the fumes emitted when cutting polystyrene foams (EPS or XPS) with hot wire tools dangerous?

A: Ventilation is always highly recommended. The smoke generated while cutting EPS foam largely consists of CO2 and water vapor, which are significantly less harmful than other common art products like aerosols and paint thinners. The toxic levels are much lower than those in wood smoke, which contains tars, resins, creosote, and acetic acid. The dust produced from cutting with saws and sanding EPS foam is more harmful than the fumes encountered while cutting foam with a hot wire tool. Always wear a good quality dust mask when saw cutting or sanding polystyrene foams.

Hot-Wire Foam Cutting Exposure Assessment During Theatrical Staging

The International Alliance of Theatrical Stage Employees conducted a comprehensive study involving workers who spent from 1 to 8 hours a day cutting foam. Their conclusion is as follows:

'The results suggest that hot-wire foam cutting workers and nearby bystanders are not at risk of overexposure to fumes generated by this task under conditions similar to those present during this assessment.'

The tests were performed in warehouses, one with a fan blowing and the other with the bay door open. Sensors were placed on special masks worn by the subjects during cutting.

Here's a link to the article:
https://www.iatse.com/_content/documents/public/IA%20Hot-Wire%20Foam%20Cutting%20Exposure%20Assessment%20Oct%204%%20FINAL.pdf

We found that the fumes emitted from burning firewood and even scented candles can be worse than those from cutting EPS foam with a hot wire. Even with this knowledge, it is always advisable to cut in well-ventilated areas and use a fan if you cannot.

However, EPS dust particles are dangerous carcinogens. Wearing a dust mask is absolutely necessary when dust particles are present. Always check with the foam manufacturer to ensure there are no health or safety hazards when cutting their foam with hot wire tools. Keep in mind that Material Safety Data Sheets (MSDS) may refer to safety hazards during foam manufacturing rather than cutting.

You can call our toll-free number at 1-866-735- and we can provide you with the tech-support number for DOW, which manufactures Styrofoam. They informed us that the fumes from cutting their foam with a hot wire are not toxic, but cutting should still occur in a well-ventilated area. (On a side note, many personal testimonials suggest that some individuals have become addicted to foam cutting. Is it the fumes or simply the joy of foam sculpting?)

Q: Is foam a fire hazard?

A: When using foam for stage props and backdrops instead of plywood, fire marshals may inquire about the fire safety of foam. EPS foam is now widely used in theaters and auditoriums worldwide, even accommodating thousands of people. After evaluating the spread rate and toxicity of foam compared to wood and cloth, fire departments have expressed satisfaction. Holding a torch to EPS foam causes it to stop melting/burning the moment the flame is removed. The smoke mainly consists of hydrocarbons and water vapor. Here’s a useful PDF from EUMEPS discussing EPS behavior in case of fire. To ignite polystyrene foams and cause them to burn, an extremely hot fire is necessary, significantly hotter than the temperatures generated by our tools directly on the foam.

For more information, you can contact DOW Chemical, who holds the patent on the manufacturing process and provides all the Material Safety Data Sheets (MSDS).

For architectural or large projects where fire could pose a potential risk, we recommend coating all foam to prevent fire spread. Below is the section from the Foam Coat MSDS showing the fire data:

SECTION IV
FIRE AND EXPLOSION HAZARD DATA
Flash Point (Method Used): Non-combustible.
Extinguishing Media: Use extinguishing media appropriate for surrounding fire.
Special Fire Fighting Procedures: None
Unusual Fire and Explosion Hazards: None
Special Fire Fighting Protective Equipment: None

Q: Is foam “Earth Friendly”?

A: Expanded polystyrene (EPS) foam is recyclable and a pre-existing waste byproduct of petroleum refinement. Production requires less energy than paper and results in less pollution. A great way to acquire foam and maintain eco-friendliness is to check with local appliance and computer stores, which often discard the EPS foam accumulated from packaging.

Q: What kind of foam would you recommend for building layouts with Dept 56 buildings or trains? Do pink and blue foams cut as well as white? Which is better for making a rigid structure?

A: Most people use white beaded foam (expanded polystyrene, or EPS) as it is the least expensive and easiest to find and cut. It is excellent for creating terrain like hills and mountains. If additional toughness or aesthetic appeal is needed to hide the small beads, it can be coated with our Foam Coat.

Conversely, pink or blue foams (extruded polystyrene, or XPS) are often used for constructing detailed structures, like walls and buildings. While they do not cut as quickly as the less dense EPS foam, they are compatible with our hot wire tools. For lightweight dioramas, using 2-inch or thicker blue or pink foam as the base rather than wood is ideal for portability and storage. An additional advantage of foam bases is the ability to create holes for unsightly wires to run straight down to electrical hookups, mimicking underground utility placements.

Q: Can your tools be used to cut polyurethane foam (sold as camera and gun case foam)?

A: We have received numerous requests for a “museum quality” foam for camera and gun cases that can be cut with hot wire tools. However, polyurethane foam is challenging to work with as it cannot be easily cut with hot wire tools. It off-gasses and degrades, potentially damaging the instruments it is designed to protect. We recommend cutting polyurethane foams only with blades or saws.

If you're interested in learning more about rubber foam insulation, contact us today for expert consultation!

Q: Can your tools be used to cut polyethylene foam (sold as camera and gun case foam, 'Plastazote' or 'Ethafoam')?

A: Hot wire tools can cut polyethylene foam, but at a slower rate due to its greater density compared to EPS foam. Ensure that you do not apply too much pressure on the blade or wire, as this could cause bending and eventual breakage. The manufacturer of Zotefoams USA confirmed that their foams are safe for cutting with a hot wire. Many of our customers successfully use hot wire tools to cut Ethafoam and other polyethylene foams, but we always advise verifying safety with the foam manufacturer prior to use.

You can also check our Gallery section for posts about creating foam inserts for instrument cases. We offer sturdy plastic cases in our Accessories section, identical to the pistol cases commonly used for travel, which are airline transport-approved.

Q: Can your tools be used to cut polyurethane foam (sold as upholstery foam and 'poly foam')?

A: Polyurethane foam should not be cut with hot wire tools. It requires excessive heat, produces toxic fumes, and leaves behind melted plastic residue. We recommend cutting polyurethane foams only with blades or saws.

Q: Can your tools be used with PVC-based corrugated sheets like Coroplast?

A: We have had success cutting Coroplast with our hot wire tools, although it is a slower process. A razor blade is faster for straight cuts, but hot wire tools are advantageous for curves. The Sculpting Tool with a wire just past 5 inches long is most effective. Always double-check with manufacturers to identify potential health or safety hazards when using hot wire tools with their materials.

Q: Will your 4-inch hot knife cut 3mm thick craft foam? The brand I buy is Darice Foamies, used to create my own stamps for mixed media artwork by gluing pieces to acrylic squares and inking the foam. Scissors and exacto knives fail to achieve clean cuts. If the 4-inch knife isn't suitable (possibly too long), what do you recommend?

A: I don’t believe this type of foam can be cut with hot wire tools. Although its composition is not explicitly stated, it is likely a polyurethane foam, which does not cut well with heat and releases toxic fumes when cut with a hot wire. Contacting the manufacturer may yield a definitive answer. We have created impressive stamps from DOW Blueboard and Owens-Corning Pinkboard foams, which ink well without dripping. The 4-inch hot knife works effectively, but for better control, I usually recommend the Original Scroll Table. The Scroll Table allows cutting thick foam into stamp shapes and slicing them into additional stamps.

Q: Will your hot wire tools work on Michaels artificial foam pumpkins or Funkins artificial pumpkins?

A: Those foam pumpkins are typically made from polyurethane foam, which should not be cut with hot wire tools. Polyurethane foam requires excessive heat, emits toxic fumes, and leaves behind melted plastic upon cutting.

Q: I want to create a large animal sculpture but can't find a sufficiently large block of foam. Can you help?

A: If you require assistance sourcing foam in your area or would like help connecting with an artist to create a custom foam prop, feel free to call us at 866.735. or contact us here.

You can build your own block of foam by stacking sheets of EPS or XPS, typically found in 2-4 inch thicknesses as 4-foot x 8-foot sheets, and securing them with skewers while cutting. After sculpting, glue the pieces using our Foam Fusion glue. If a silver Mylar coating is present, it must be removed before gluing. The seams can be easily concealed with Foam Coat. Check out our gallery for a dog sculpture showcasing how Colleen glued pink insulation foam pieces together.

We also offer 12-inch x 14-inch x 22-inch EPS foam blocks available on our website.

Q: I cannot find pink or blue foam in my area. Perhaps it's not cold enough? I did discover polyurethane foam sheets with thin foil layers on both sides. If I remove the foil, will hot tools work on that type of foam, or should I continue searching for EPS?

A: Polyurethane foam is highly toxic and does not cut well with heat. You should be able to find white beaded EPS insulation foam, often having a thin clear plastic moisture barrier that can be easily peeled off. This foam is much easier to cut than blueboard and pinkboard, and it has memory, regaining its shape if slightly compressed. It is lighter and generally less expensive. Typically, those engaged in fine scale modeling opt for extruded blueboard and pinkboard for their absence of bubbles. If texture is a concern, you can apply a thin layer of Foam Coat to alleviate the bubble texture. You will find that white beaded EPS foam, when coated with Foam Coat, is more economical, aesthetically pleasing, lighter, and easier to work with.

Q: What is "open cell foam"?

A: Open cell structured foams contain interconnected pores forming a network, which is relatively soft. The “crunchy” foam commonly used in floral craft projects exemplifies open cell foam.

Q: What is "closed cell foam"?

A: Closed cell foams do not feature interconnected pores. Typically, closed cell foams exhibit higher compressive strength due to their structure. The closed cell configuration results in superior dimensional stability, low moisture absorption coefficients, and higher strength compared to open cell structured foams.

Examples of closed cell foams include expanded polystyrene (EPS), made from pre-expanded polystyrene beads, thus sometimes referred to as bead-board foam. EPS is commonly available in blue, pink, yellow, and green insulation sheets. Extruded polystyrene foam (XPS) is another type of closed cell foam with trade names such as 'INSUboard,' 'Styrofoam,' 'Foamular,' 'Greenguard,' and 'Foamcore.'

Q: We need to protect hand gauges during storage. We plan to place polyethylene foam in Lista cabinet drawers, cutting out 'beds' for various measuring instruments such as OD micrometers, thread gauges, and other types of equipment. We will not be cutting through the foam but creating shapes in it for the gauges to rest. Which tools do you recommend?

A: Our tools can cut through polyethylene foam, though not nearly as quickly as the white beaded EPS foam. The finer the blade, the quicker and neater the cut will be. Cutting takes about three seconds per inch, leading to melted foam buildup that must be wiped off the 4-inch Hot Knife and Freehand Router between cuts. I suggest considering the K44P6 Kit instead of the K47 Kit, as well as purchasing the Sculpting Tool separately. The Pro 6 Knife cuts foam faster than the 4-inch knife. I am also concerned that the blade on the 4-inch knife could break due to the tougher foam.

Here is a link showing our tools used to cut polyethylene foam. Attempts to cut polyethylene foam at higher heat resulted in carbon buildup on the blade, which halts cutting and is challenging to clean off. It's prudent to consult the manufacturer for Material Safety Data Sheets (MSDS) regarding their foam when cutting with heat.

Q: What kind of foam are pool noodles made from? Can I cut them with your tools?

A: Foam pool noodles are typically manufactured from polyethylene foam, which can be effectively cut with hot wire tools.

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