Gluing Polyurethane foam

How Polyurethane foam behaves when you bond it

Very absorbent, so a runny adhesive disappears into the foam and stiffens a block that was supposed to stay soft. Solvent-based products can dissolve it outright, which is why upholstery work uses foam-specific sprays.

Polyurethane foam ranges from soft open-cell upholstery foam to rigid closed-cell insulation. Open cells absorb low-viscosity adhesive and can create a stiff, starved bond, while some solvents and high application temperatures can damage particular formulations.

Use clean, dry foam with no friable skin. Brush or vacuum loose particles without compressing the cells. Choose a foam-rated spray, dispersion or low-temperature system and apply the minimum uniform coat needed. Test solvent and heat compatibility on an offcut and use broad, light pressure.