UN 0433 — Powder cake, wetted
Placard: Explosive 1.1C. ERG Guide 112. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 0433 is Powder cake, wetted, a desensitized or wetted Class 1.1C explosive substance assigned to ERG Guide 112. Wetting, wax or other desensitizers reduce sensitivity, but the material can become more dangerous if dried, heated, damaged or contaminated.
Hazard overview: UN 0433 presents a serious explosive hazard if initiated. Desensitizing material reduces sensitivity during normal transport, but drying, fire exposure, shock, friction or contamination can increase detonation or deflagration risk. Damaged, leaking or drying material should be treated as extremely hazardous.
Response guidance: For a UN 0433 incident, responders should confirm the material using shipping papers, placards, package markings, SDS where applicable and ERG Guide 112. Establish incident command, isolate the area, deny entry, request law enforcement and EOD support, and withdraw personnel if fire involves the explosive material or containers.
Firefighter training notes: Training should emphasize recognizing Class 1 explosive placards, establishing command early, using standoff distance, denying entry and requesting bomb squad or EOD support. Common tactical errors include approaching packages for identification, moving damaged items, fighting fire too close and underestimating fragmentation distance. Use ERG 112, shipping papers and local explosive incident SOP.
Regulatory context: Powder cake, wetted is regulated as a Class 1 explosive hazardous material. Transportation, storage, quantity limits, fire code controls and reporting requirements may vary by jurisdiction. Responders should verify current requirements through shipping papers, SDS or product documents and applicable DOT, ATF, OSHA, NFPA, military, state or local authority guidance.
Storage & handling: Powder cake, wetted should be stored only in approved packaging, magazines or authorized explosive storage areas, separated from ignition sources, incompatible materials and unauthorized access. Packages should be protected from heat, impact, friction, moisture where relevant and physical damage according to product documentation and applicable explosive storage regulations.
UN 0433 Quick Details
Common Hazards of UN 0433
- Mass explosion hazard; wetted powder cake may detonate or deflagrate violently if initiated.
- Water or alcohol wetting reduces sensitivity, but drying can significantly increase the hazard.
- Heat, shock, friction, contamination or loss of wetting agent may increase initiation risk.
- Detonation may produce severe blast overpressure and fragmentation.
- Fire may produce irritating or toxic combustion products.
- Damaged, leaking or drying material should be treated as extremely hazardous.
Chemical Identity & Physical Properties
Compressed or molded explosive powder composition dampened with water or alcohol to reduce sensitivity. Typically appears as a cake or block form, color varies from white to brown depending on composition.
| Also known as | Wetted powder cakeDampened explosive powderMoistened powder cakeWet explosive composition |
| Appearance | Compressed or molded explosive powder composition dampened with water or alcohol to reduce sensitivity. Typically appears as a cake or block form, color varies from white to brown depending on composition. |
| Flash Point | Not applicable (explosive solid) |
| Boiling Point | Not applicable (decomposes/detonates) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Water is used as desensitizer; drying increases explosion hazard |
Fireground Response Guidance — UN 0433
Extinguishing Media
PPE Requirements
For UN 0433, distance, cover and evacuation are more important than close-range PPE. Structural firefighting gear and SCBA may be used only for remote exposure protection or support roles; direct approach or handling should be limited to qualified EOD or explosive specialists under incident command.
Isolation & Evacuation
First Actions for a UN 0433 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away and deny entry to the hazard area.
- Stage responders upwind, uphill and outside the recommended isolation distance.
- Request law enforcement, bomb squad or EOD, hazmat and additional command resources immediately.
- Do not handle, move or disturb explosive articles unless directed by qualified explosive ordnance personnel.
- Watch for damaged packaging, leakage or drying of desensitized material and report it to incident command immediately.
- Do not fight fire involving explosives at close range; withdraw and protect life safety first.
- Protect exposures only from a safe, remote position if directed by incident command and local SOP.
- Use ERG Guide 112, shipping papers and incident command to set isolation and evacuation distances.
📋 Copy & Share Field Card
UN 0433 — Powder cake, wettedUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.