Frequently Asked Questions

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What types of foam can be cut with your hot wire cutters?

Many types of rigid and soft foams can be cut with our hot wire cutters, however due to the chemicals in many of these foams that off-gas when cutting, we only recommend cutting the following types of foams:

  • Expanded Polystyrene (EPS)
    Expanded Polystyrene Foam
  • Extruded Polystyrene (XPS) also know as “blue” and “pink” board.
    Extruded Polystyrene Foam

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Where can I purchase EPS foam blocks?

Most areas of the world use polystyrene for food service products, packaging, construction and marine uses. This means a foam block molder is usually not far from your location no matter where in the world you are located. Click below to find:

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What is Expanded Polystyrene?

Expanded polystyrene (EPS) foam is the most common foam cut for architectural shapes, structural insulated panel systems (SIPS), insulated concrete forms (ICF), precast concrete molds and models, theming, and sign making. EPS is technically a plastic. The word ‘plastic’ comes from Greek plastikos, which means capable of being molded. The freedom to be creative with custom designs is a major reason why we find EPS so valuable today. It is also interesting to know that EPS foam is the same material (polystyrene) used to make hard shell CD cases and other household products. To find polystyrene in everyday products, look for recycling number ‘6’.

  • EPS Characteristics

    • Light Weight: Typically 1 lb. – 2 lbs. / cubic foot
    • Highly Insulative: Because there is no thermal drift, 1 inch provides lifetime R-3.6 to R-4.2 values (depending on density)
    • Environmentally Friendly: EPS has always been CFC- and HCFC-Free
    • Manufactured Locally: Hundreds of plants throughout the world

  • Chemical Properties

    Expanded polystyrene is resistant to water and all aqueous solutions of salts, alkalis, and acids. Essential oils such as those present in both the peel of citrus fruits and whole-fruit drinks attack expanded polystyrene, but it is resistant to both vegetable and animal fats. It is also resistant to mineral waxes of the kind used to guard against corrosion, provided they contain no solvent.

    Since most organic solvents attack expanded polystyrene, particular care must be taken in the choice of adhesives, paints, coatings, and mold release agents. Plastics containing plasticizers (e. g. flexible PVC) should not be kept in contact with expanded polystyrene because of the risk of plasticizer migration.

  • Biological Effects

    Small amounts of pentane vapors escape from polystyrene while it is stored and being processed. Ventilation should be provided, particularly when expanded polystyrene is cut with hot wires, since pentane and small amounts of styrene can be released. The threshold values, workplace limits, etc. for both pentane and styrene must be observed.

    The National Institute for Occupational Safety and Health (NIOSH) has established Recommended Exposure Limits (REL’s) for average airborne concentration of pentane at 120 ppm, with a ceiling limit of 610 ppm (15 minute). Typically EPS forming and cutting facilities operate at levels well under these limits. (PDF document with findings from a NIOSH inspection of a foam expanding and cutting facility.)

    Expanded polystyrene has no nutritive value for animals. It does not rot, is not soluble in water, and it does not give off water-soluble substances which could lead to groundwater contamination. If local regulations allow, waste expanded polystyrene can be safely disposed of with household garbage by landfill. Expanded polystyrene has been manufactured and processed for over fifty years and during that time no harmful effects on health have been recorded.

  • Fire Characteristics

    Like all organic materials, expanded polystyrene is combustible, and like most packaging materials it is also flammable. Its burning behavior depends largely on the polystyrene grade in question. A distinction has to be made between products without fireproofing additives and products containing additives. Expanded polystyrene that contains flame retardant makes it more difficult to ignite and slows the spread of flame noticeably.

    EPS Recycling International,
    Chemical, Biological and Fire Data Courtesy of BASF Corporation, and
    Centers for Disease Control and Prevention

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How is expanded polystyrene (EPS) foam made?

Styrene is composed of Benzene (liquid) and Ethylene (gas), both of which are petroleum products. EPS begins as a styrene monomer which goes through a process where the styrene monomers link into larger molecules called polystyrene.

Expanded polystyrene or EPS foam is made from polystyrene pellets or beads that are puffed up with steam. The process is similar to cooking rice with steam. Usually a small amount (approx 4%-6%) pentane or another “blowing agent” is added to the hard polystyrene pellets to enable the expansion process. When these independent foam beads are in a mold they take the shape of the mold and hold that shape when they dry and cool down.

The polystyrene beads grow to more than 40 times their original size and when the process is complete the usable EPS is about 98% air* which gives it features that are desired. Expanded polystyrene is a rigid, insulating, light weight, and biologically friendly foam.

European Manufacturers of Expanded Polystyrene:

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How can I coat EPS foam after cutting it?

Coating foam can be done with a variety of coating products depending on your application.

  • Typically foam architectural elements are coated with an exterior insulation and finish system (E.I.F.S.) synthetic stucco coating. These coatings consist of a base coat adhesive which includes embedded mesh. The base coat and mesh gives the foam structural integrity, on which a colored, textured finish coat is applied.

    We provide the 7300 Direct Coat, a coating machine for applying the base coat to linear trim and moldings.

  • Foam is also coated with an epoxy, polyurea, or polyurethane coatings for a smooth hard plastic finish. These coatings also give the foam structural integrity and upon which paint or other finish is applied for theming, sign making, and architectural elements. Epoxy, polyurea, and polyurethane finishes are also used for precast concrete applications to make a smoother and longer lasting surface for casting concrete and glass fiber reinforced concrete (GFRC).

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How can I dispose of or recycle my waste foam?

Because EPS foam is expanded, it consists of about 90% air. This is beneficial for most purposes that it is used for, however, this also means it will use high volume for shipping. You can use a foam compactor for compressing the air out of the waste which helps with transportation issues.

Keeping EPS foam out of the landfills is a primary objective of the EPS Molders Association, of which Hotwire Direct is a member. For recycling, many creative options exist.

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Can I purchase products online?

Yes, most products that we ship via FedEx can be purchased directly online with a credit card. Please contact us if you have any questions on products before purchasing. To begin shopping online, click here: online shopping.

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Is financing available?

Yes financing is available in the USA. We have partnered with outside companies who specialize in equipment financing. If you would like more information on how to finance your equipment, please visit our finance page.

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