Rigid Foams
Rigid foams are indispensable in model making for creating lightweight yet stable structures, base forms, and detailed architectural models. These materials are known for their ability to be cut, shaped, and sanded with precision, making them ideal for projects requiring crisp lines and strong, unyielding components.
---Quick Reference: Rigid Foams
Use this quick guide to understand the primary characteristics and common uses of different rigid foams in model making.
| Material | Key Characteristics | Common Model Making Uses |
|---|---|---|
| Foamboard | Polystyrene foam core with paper/card facings, lightweight, easy to cut, rigid, flat. | Architectural models, presentation boards, lightweight structures, model railway baseboards. |
| KAPA Foamboard | Premium polyurethane foam core, superior flatness & stability, very clean cuts. | Professional architectural models, exhibition displays, high-precision finishing. |
| Foamed PVC | Rigid, lightweight, durable, excellent chemical/moisture resistance, smooth surface. | Robust architectural models, signage, display stands, high-durability components. |
| Polystyrene Foam Sheets (EPS) | Expanded beads, extremely lightweight, affordable, can be crumbly, dissolves with some solvents. | Bulk shaping, terrain building, basic models, void-fill, insulation. |
| XPS Foam (Extruded Polystyrene) | Denser, smooth, closed-cell, less crumbly than EPS, moisture-resistant. | Architectural models, detailed terrain, dioramas, carving, durable base structures. |
Foamboard
Foamboard, or foam core board, typically consists of a lightweight polystyrene foam core sandwiched between two sheets of paper or card. This construction provides excellent rigidity and flatness for its weight.
Characteristics:- Material: Polystyrene foam core with paper or card facings.
- Texture & Consistency: Smooth, flat surface. The core can be easily compressed or dinged if not handled carefully.
- Workability: Very easy to cut with a craft knife, providing clean edges. It can be scored and folded to create angles. Takes glue and paint well on its paper surface.
- Weight: Extremely lightweight.
- A highly versatile material for architectural model making, presentation boards, prototyping, and creating temporary or lightweight structures.
- Ideal for walls, floors, roofs, and massing models due to its ease of cutting and assembly.
- Can be used for model railway baseboards or scenery elements where light weight is crucial.
- Generally available in various sheet sizes and thicknesses.
KAPA Foamboard
KAPA Foamboard is a premium brand of foamboard, often distinguished by its higher quality foam core and sometimes different facings compared to standard foamboard, offering enhanced performance for professional model makers.
Characteristics:- Material: Often features a polyurethane foam core with chromo substitute cardboard facings, providing superior flatness and stability.
- Texture & Consistency: Very smooth, non-porous surfaces. Known for exceptional rigidity and resistance to warping.
- Workability: Allows for extremely clean and precise cuts without crumbling. It is often preferred for complex architectural details and fine finishing.
- Weight: Lightweight yet remarkably stable.
- Highly favoured in professional architectural model making, exhibition displays, and high-quality presentations where precision and a flawless finish are paramount.
- Its stability makes it excellent for intricate multi-layered structures.
- Supplied in various sheet sizes and thicknesses, recognised for its consistent quality.
Foamed PVC (Foamex / Sintra)
Foamed PVC, often known by brand names like Foamex or Sintra, is a rigid, lightweight, and extremely durable closed-cell foamed plastic sheet material.
Characteristics:- Material: Extruded polyvinyl chloride (PVC) foam.
- Texture & Consistency: Smooth, matte surface. It is rigid and holds its shape exceptionally well.
- Durability & Resistance: Excellent chemical and moisture resistance, and very durable against impact.
- Workability: Can be cut, routed, drilled, and heat-formed with appropriate tools. It can be glued with specialised plastic cements or superglues. Its smooth surface takes paint and vinyl graphics very well.
- Ideal for robust architectural models, signage, display stands, and parts requiring high durability and resistance to environmental factors.
- Used in situations where a solid, non-absorbent, and rigid panel is needed.
- Available in various colours and thicknesses.
Polystyrene Foam Sheets (EPS - Expanded Polystyrene)
Polystyrene foam sheets, typically referring to Expanded Polystyrene (EPS), are a very common, affordable, and extremely lightweight foam, distinguishable by its characteristic bead-like structure.
Characteristics:- Material: Expanded Polystyrene.
- Texture & Consistency: Made of numerous small, fused plastic beads. Can be somewhat crumbly when cut or sanded, producing tiny static foam balls.
- Weight: Extremely lightweight due to its high air content.
- Resistance: Not resistant to solvents found in many glues and paints (e.g., aerosol spray paints, contact cements, some plastic glues) which will dissolve it.
- Primarily used for bulk shaping, basic architectural models, terrain building in wargaming, and as void-fill or insulation.
- Excellent for roughing out large forms that will then be covered with other materials (e.g., plaster, fabric).
- Its affordability makes it suitable for large-scale, less detailed projects or prototypes.
- Widely available in various thicknesses and block sizes, often from construction or craft suppliers.
XPS Foam (Extruded Polystyrene - e.g., Styrofoam)
XPS foam, often known by brand names like Styrofoam (in its insulation board form) or sometimes incorrectly as 'Foamboard' in general usage, is an Extruded Polystyrene foam characterised by its smooth, closed-cell structure, offering superior properties compared to EPS.
Characteristics:- Material: Extruded Polystyrene.
- Texture & Consistency: Denser and smoother than EPS, with a closed-cell structure (no visible beads). This makes it less crumbly when cut.
- Resistance: More resistant to moisture and less prone to crumbling than EPS. Like EPS, it can be dissolved by certain solvents.
- Colours: Commonly found in distinctive colours such as dark grey or dark blue, often indicating its use as an insulation board.
- Highly valued for architectural models, detailed terrain, dioramas, and carving projects where a smooth finish and structural integrity are desired.
- Its consistent density allows for more precise cutting and finer detail than EPS.
- Good for creating durable base structures that require less surface finishing than EPS.
- Often available as insulation boards from building suppliers, as well as in smaller sheets for craft and modelling.
