UN 1435 — Zinc skimmings
Placard: Dangerous When Wet. ERG Guide 138. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1435 is Zinc skimmings, a dangerous-when-wet metal powder or residue assigned to ERG Guide 138. Fine powder can produce hydrogen with moisture and may burn intensely if dispersed, heated or ignited.
Hazard overview: UN 1435 presents water-reactive metal powder, hydrogen generation, dust ignition and re-ignition hazards. Avoid dust clouds, keep the material dry and use only compatible Class D or dry media under incident command.
Response guidance: For a UN 1435 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 138. Establish incident command, isolate the area, stay upwind, prevent incompatible contact and choose extinguishing or spill-control actions based on the ERG, SDS and local SOP.
Firefighter training notes: Training for UN 1435 should emphasize dangerous-when-wet behavior, flammable hydrogen gas generation, dry-agent selection, moisture exclusion and safe standoff. Common errors include using water or foam directly, entering low areas without monitoring and underestimating re-ignition. Use ERG 138, SDS and hazmat SOP.
Regulatory context: Zinc skimmings is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Zinc skimmings should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, acids, oxidizers, heat and ignition sources. Protect containers from impact, corrosion, dust release where relevant and unauthorized access.
UN 1435 Quick Details
Common Hazards of UN 1435
- DANGEROUS WHEN WET; contact with water or moisture can release flammable hydrogen gas.
- May ignite on contact with water or moist air.
- Reaction with water may generate heat, pressure and violent spattering.
- May be ignited by heat, sparks or flames and may re-ignite after apparent extinguishment.
- Containers may rupture or explode when heated.
- Runoff or water application may spread contamination and increase gas generation.
- Avoid low, enclosed or poorly ventilated areas where reaction gases may accumulate.
- Fine metal powder can ignite, burn intensely or form dust-air explosion hazards if dispersed.
Chemical Identity & Physical Properties
Gray to dark gray metallic solid residue or powder consisting of zinc oxide and metallic zinc removed from molten zinc surfaces. May contain flux residues and other impurities.
| Also known as | Zinc drossZinc skimmingsZinc skimZinc residueGalvanizing skimmings |
| Appearance | Gray to dark gray metallic solid residue or powder consisting of zinc oxide and metallic zinc removed from molten zinc surfaces. May contain flux residues and other impurities. |
| Flash Point | Not applicable (water-reactive solid) |
| Boiling Point | Not applicable (decomposes/reacts with moisture) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts with water or moisture to produce flammable hydrogen gas. May ignite spontaneously on contact with water or in moist air. |
Fireground Response Guidance — UN 1435
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for any suspected flammable hydrogen gas, fire, dust or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS and incident command; keep PPE and tools dry near the material.
Isolation & Evacuation
First Actions for a UN 1435 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Avoid low areas where flammable hydrogen gas may collect.
- Do not touch spilled material or damaged containers unless properly trained and equipped.
- Keep water, foam and moisture away from the released material unless incident command confirms a compatible cooling or control use.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or leak area and expand the perimeter if water contact, fire or gas generation is suspected.
- Use ERG Guide 138, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1435 — Zinc skimmingsUse 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.