Selecting the right adhesive for Styrofoam (polystyrene foam) is crucial to avoid melting or damaging the material. The best glues are typically those free from harsh solvents that can degrade polystyrene.
Recommended Glues for Styrofoam
- PVA Glue (White Craft Glue): This water-based adhesive, such as Elmer's Glue-All or similar school glues, is readily available, non-toxic, and safe for Styrofoam. It's suitable for light-duty applications and dries relatively clear. It requires a longer drying time.
- Specialized Foam Adhesives: Many manufacturers produce glues specifically designed for foam materials, often labelled "Styrofoam safe," "foam glue," or "polystyrene compatible." These offer strong bonds without damaging the foam. Examples include UHU POR, Liquid Nails for Foamboard, or Gorilla Glue (Original formula, used sparingly as it expands, or their clear, non-expanding versions if foam-safe).
- Foam-Safe Spray Adhesives: Ideal for bonding large surfaces of Styrofoam or attaching fabric to foam. Ensure the product is explicitly stated as "foam-safe" (e.g., 3M Super 77 Multipurpose Adhesive, but always check the can for foam compatibility as formulations can vary, or dedicated foam spray glues). Apply in a well-ventilated area.
- Low-Temperature Hot Glue: Use a low-temperature glue gun and corresponding low-melt glue sticks. Standard high-temperature hot glue will melt Styrofoam. It's always best to test on a scrap piece first.
- Silicone Adhesive/Caulk: 100% silicone caulks or silicone-based adhesives can provide a strong, flexible, and often waterproof bond. They generally do not contain harsh solvents. Curing time can be longer.
- Epoxy (Foam-Safe): Some epoxies are suitable, particularly those with longer cure times (e.g., 30-minute or longer) as they generate less exothermic heat during curing. Always check the manufacturer's recommendations for use on polystyrene foam. Avoid fast-setting epoxies that can heat up significantly.
Glues to Avoid with Styrofoam
- Solvent-Based Adhesives: Most super glues (cyanoacrylates, unless specifically labelled foam-safe), model cements (for plastic models), rubber cements, contact cements containing toluene or xylene, and many general-purpose strong adhesives contain strong solvents that will dissolve or melt Styrofoam on contact.
- High-Temperature Hot Glue: The heat from standard (high-temperature) hot glue guns will melt Styrofoam, compromising the bond and damaging the material.
- Most Polyurethane Glues (Expanding Type): While some, like Original Gorilla Glue, can work if used very sparingly and clamped (as they expand), the expansion can sometimes deform thin Styrofoam. Always test. Some newer polyurethane formulas might be less aggressive.
General Tip: Always test any adhesive on a small, inconspicuous scrap piece of Styrofoam before applying it to your main project to ensure compatibility and desired results.
