Lead wool is a fibrous metallic form of lead produced by shredding, shaving, or extruding high-purity lead into fine strands. It resembles steel wool but is much heavier, softer, and completely non-sparking.
Lead wool is valued for its compressibility, conformability, sealing capability, vibration damping, and radiation attenuation rather than mechanical strength.
Typical Chemical Composition
| Element | Typical Content (%) |
|---|---|
| Lead (Pb) | 99.9 – 99.99 |
| Silver (Ag) | ≤ 0.005 |
| Copper (Cu) | ≤ 0.002 |
| Bismuth (Bi) | ≤ 0.002 |
| Antimony (Sb) | ≤ 0.001 |
| Tin (Sn) | Trace |
Very high purity ensures maximum softness and compressibility.
Key Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 12 – 17 MPa |
| Yield Strength | 5 – 10 MPa |
| Elongation | 40 – 60% |
| Hardness (Brinell) | 4 – 6 HB |
| Elastic Modulus | ~16 GPa |
| Compressibility | Very high |
| Resilience | Low (plastic deformation) |
Physical Properties
| Property | Value |
|---|---|
| Density (solid lead) | 11.34 g/cm³ |
| Apparent Density (wool) | 1.5 – 4.0 g/cm³ |
| Melting Point | 327.5 °C |
| Thermal Conductivity | ~35 W/m·K |
| Electrical Conductivity | ~4.8 MS/m |
| Acoustic Damping | Excellent |
| Radiation Attenuation | Excellent |
| Magnetic | Non-magnetic |
| Sparking | Non-sparking |
Metallurgical & Strengthening Behavior
| Mechanism | Effect |
|---|---|
| Cold Working | Minimal (rapid recovery) |
| Solid Solution Alloying | Rarely used |
| Heat Treatment | Not applicable |
| Precipitation Hardening | Not possible |
Lead wool is intentionally kept as soft as possible; no metallurgical strengthening is desired.
Key Characteristics
✔ Extremely soft and malleable
✔ Easily compressible into voids
✔ Excellent sealing performance
✔ Outstanding vibration and noise damping
✔ Excellent radiation shielding when compacted
✔ Non-sparking and chemically stable
❌ Low mechanical strength
❌ Toxic – controlled handling required
❌ Not load-bearing
Refining & Processing Properties
Raw Material:
Primary refined lead or high-purity secondary lead
Manufacturing Process:
Lead melting → billet casting → mechanical shaving / extrusion → fiber size
control → cleaning → packaging
Processing is entirely mechanical with no chemical alteration.
Fabrication & Workability (In Use)
| Operation | Suitability |
|---|---|
| Packing | Excellent |
| Compression | Excellent |
| Molding in situ | Excellent |
| Welding | Not applicable |
| Machining | Not applicable |
| Reuse | Limited |
Available Commercial Forms
Loose lead wool
Compressed wool rolls
Pre-packed sealing strips
Radiation-grade compacted wool
Custom fiber thickness grades
Supplied in bags, coils, or compressed blocks.
Applications of Lead Wool
Chemical & Process Industries
Expansion joint packing, acid-resistant seals, flange gap filling
Radiation & Nuclear
Shielding around pipes, penetrations, and enclosures
Mechanical & Industrial
Vibration isolation, sound damping, shock absorption
Construction & Infrastructure
Roof penetrations, cable sleeves, historic building restoration
Safety-Critical Uses
Non-sparking packing in explosive environments
Advantages
✔ Superior conformability
✔ Permanent sealing through plastic deformation
✔ Environmental durability
✔ Dual sealing and radiation shielding function
Health, Safety & Regulations
⚠ Lead is toxic. Gloves, PPE, dust control, and regulated disposal are mandatory.
Regulated under REACH, OSHA, EPA, and RoHS (industrial exemptions apply).
Why Choose Lead Wool?
Choose lead wool when irregular void sealing, vibration damping, radiation shielding, non-sparking behavior, and long-term durability are required and structural strength is not critical.
Lead wool remains a uniquely effective metallic packing material where no alternative matches its combined compressibility, density, and shielding performance.