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Get PriceIn the construction and maintenance of industrial furnaces and high-temperature equipment, fast and reliable lining installation is essential. Moreover, besides traditional fire bricks, monolithic refractories have become widely used because they provide greater flexibility, excellent integrity, and strong adaptability to complex structures.
Among these products, refractory gunning material (spray mix) and trowelling castable (refractory patching material) are two of the most frequently used options. However, many users confuse them because both materials are applied to the furnace surface. In reality, their installation methods, performance features, and ideal application scenarios differ significantly.
Therefore, this article offers a clear, practical comparison so you can choose the right material confidently.
This is the fundamental difference that directly affects the final lining quality and overall performance.
| Comparison Dimension | Refractory Gunning Material (Spray Mix) | Trowelling Castable (Patching Material) |
|---|---|---|
| Installation Method | Spraying / gunning | Manual or mechanical trowelling |
| Key Equipment | Spray gun, air compressor, wet mixer or pump | Trowel, scraper, simple mixer |
| Working Principle | Dry or wet spraying; the material is projected at high velocity onto the surface, forming a dense layer through impact bonding and particle interlocking. | Pre-mixed plastic or castable material is pressed and compacted directly onto the substrate by hand or small equipment. |
| Installation Speed | Extremely fast; ideal for large areas and complex shapes. | Slower; relies largely on manual work. |
| Technical Requirements | High; requires skilled operators to control angle, water ratio, and rebound. | Moderate; mainly depends on workmanship for compaction and surface flatness. |
In simple terms, gunning means “shooting material onto the surface,” while trowelling means “pressing and smoothing material manually or mechanically.”
As a result, the materials behave differently during construction.
Because their installation methods vary, the final lining structure and performance also differ. For example, gunning generally forms a rougher but faster-built layer, while trowelling produces a smoother and more precise surface.
| Performance Aspect | Refractory Spray Mix | Trowelling Castable / Patching Material |
|---|---|---|
| Lining Structure | Layered and compact structure formed by high-speed particle impact. | Uniform, dense structure formed by controlled compaction. |
| Initial Bond Strength | Very high; can easily adhere to vertical and overhead surfaces. | Dependent on material plasticity and compaction; difficult on overhead surfaces. |
| Overall Integrity | Excellent; seamless monolithic lining with superior thermal shock resistance. | Good; may form joints between multiple trowelled layers. |
| Surface Quality | Rougher surface, may require additional finishing. | Smooth and uniform surface; ideal for accurate furnace dimensions. |
| Material Loss | Has rebound loss (especially dry gunning). | Almost zero rebound; nearly 100% utilization. |
Each material clearly performs better in specific situations. Consequently, selecting the right one depends heavily on working temperature, surface geometry, and required precision.
| Comparison Dimension | Refractory Gunning Material | Trowelling Castable / Patching Material |
|---|---|---|
| Best Use Cases | 1.Large-scale new furnace linings | 1.Protective sealing or insulation coatings on brick linings |
| 2.Emergency and rapid repairs | 2.Fine repair of joints, cracks, voids, and eroded surfaces | |
| 3.Complex geometries (tube walls, arch roofs) | ||
| 4.Thick lining construction (>100 mm) | 3.Thin refractory linings with thickness below 50 mm | |
| 5.Fine repair and gap filling | ||
| 6.Thin-layer linings (<50 mm) | 4.Areas requiring smooth surfaces and precise dimensions | |
| 7.Areas requiring smooth surfaces and precise thickness | ||
| Typical Industries | Steelmaking, cement, power (CFB boilers), non-ferrous metallurgy | Petrochemical furnaces, ceramic kilns, maintenance coatings, sealing layers |
In addition, construction speed, labor cost, and material waste play important roles in your decision-making process.
| Cost & Labor Aspect | Spraying / Gunning | Trowelling Castable |
|---|---|---|
| Equipment Investment | High (specialized spraying equipment required) | Low (basic mixing and hand tools) |
| Labor Cost | Few workers but require skilled operators | More workers but lower skill barrier |
| Material Utilization | 85–95% due to rebound | Nearly 100% |
| Overall Cost Efficiency | Most cost-effective for large or thick projects | Most economical for small repairs or thin layers |
Choose Refractory Gunning Material When You Need:
Choose Trowelling Castable / Patching Material When You Need:
Refractory gunning mixes and trowelling castables are not competitors. Instead, they complement each other and often work together to improve kiln and furnace lining performance. In fact, many modern industrial installations use both solutions: gunning mixes for fast, large-area construction and trowelling mixes for sealing, smoothing, or precision repairs.
By understanding the main differences between these two materials—and by evaluating your temperature conditions, construction timeline, surface quality requirements, and budget—you can choose the most effective and economical solution for your project.
If you need expert guidance, Kerui Refractory provides professional technical support and high-performance monolithic materials to help you achieve safe, efficient, and long-lasting furnace operation.