Pneumatic or pyrotechnic device used in special effects to launch debris, dirt, glass, or other materials upward – creating explosions, bullet hits, and impact effects on set by propelling breakaway materials at controlled velocities and trajectories.
What is a Mortar?
A Mortar (Effects Mortar) is a pneumatic or pyrotechnic device that propels materials upwards. In film production, it creates explosions, impacts, and debris effects using practical means.
Basic Principle
| Aspect | Description |
|---|---|
| Function | Propel material upwards |
| Propulsion | Compressed air or pyro |
| Output | Debris, dirt, fragments |
| Control | Timing, force |
Mortar Types
| Type | Propulsion |
|---|---|
| Air Mortar | Compressed air |
| Pneumatic | Compressor |
| Pyrotechnic | Black powder |
| Electric | Solenoid |
Air Mortar
| Aspect | Description |
|---|---|
| Propulsion | Compressed air |
| Advantage | Safe, repeatable |
| Pressure | Adjustable |
| Trigger | Electric/Manual |
Pyrotechnic Mortar
| Aspect | Description |
|---|---|
| Propulsion | Propellant charge |
| Force | Higher |
| Single Use | Per charge |
| License | Pyrotechnician required |
Components
| Part | Function |
|---|---|
| Barrel | Guidance |
| Chamber | Pressure build-up |
| Trigger | Activation |
| Charge | Material |
Materials for Launch
| Material | Effect |
|---|---|
| Dirt | Explosions |
| Breakaway Glass | Window destruction |
| Styrofoam | Light debris |
| Cork | Safe particles |
Typical Applications
| Effect | Description |
|---|---|
| Explosion | Dirt hits |
| Bullet Impact | Wall impacts |
| Debris | Flying fragments |
| Water | Water geyser |
Setup
| Step | Description |
|---|---|
| 1 | Determine position |
| 2 | Bury/hide mortar |
| 3 | Load material |
| 4 | Wiring |
Concealment
| Method | Description |
|---|---|
| In Ground | Buried |
| Under Props | Hidden |
| In Walls | Built-in |
| Camouflage | Covered |
Timing
| Aspect | Description |
|---|---|
| Cue | From Director/SFX |
| Sync | With action |
| Delay | Adjustable |
| Multiple | Sequenced |
Safety
| Measure | Description |
|---|---|
| Perimeter | Safety distance |
| Material | Harmless |
| Eye Pro | Safety glasses |
| Briefing | Crew information |
Safety Distances
| Material | Minimum Distance |
|---|---|
| Soft Debris | 3-5 meters |
| Dirt | 5-10 meters |
| Pyro | 10+ meters |
| Performers | Depends on effect |
Collaboration
| With Whom | Regarding |
|---|---|
| 1st AD | Timing, Safety |
| Stunt Coord | Performer safety |
| Camera | Framing |
| Sound | Warning |
Equipment List
| Device | Function |
|---|---|
| Mortar Barrels | Various sizes |
| Compressor | For Air Mortar |
| Firing Box | Trigger system |
| Debris | Launch material |
Cost Factors
| Factor | Impact |
|---|---|
| Quantity | Number of effects |
| Size | Scale of effects |
| Material | Special debris |
| Crew | SFX personnel |
VFX Enhancement
| Aspect | Description |
|---|---|
| Base | Practical effect |
| Enhancement | CG extension |
| Composite | Combined |
| Advantage | Baseline realism |
Challenges
| Problem | Solution |
|---|---|
| Timing | Rehearsals, cues |
| Visibility | Conceal well |
| Wind | Adaptation |
| Repeatability | Quick reset |
Rehearsals
| Phase | Description |
|---|---|
| Dry Run | Without material |
| Low Power | Reduced force |
| Full Test | Full effect |
| On Camera | With recording |
Documentation
| Aspect | Description |
|---|---|
| Pressure/Charge | Record |
| Position | Mark |
| Timing | Document |
| Video | Record tests |
Best Practices
| Practice | Reason |
|---|---|
| Safety First | Always |
| Test Fires | Before shooting |
| Clear Calls | Communication |
| Document | For repetition |
Today
Mortars remain an important tool for practical special effects. Although VFX can generate many explosions digitally, practical mortar effects provide an authentic foundation and convincing actor reactions. The combination of practical effects and digital enhancement is now standard for high-quality action sequences.