A Practical Insider’s Look at Lead Oxide (Litharge) for Fire Assay and Specialty Glass

If you work in a fire assay lab or high-lead glass line, you already know the drill: consistency beats everything. I’ve toured enough assay rooms to notice one thing—when Lead Oxide purity wobbles, recoveries wobble. Fizachem’s litharge, made from specially refined lead out of Zhongyuan Building, No.368 Youyi North Street, Shijiazhuang, China, has been getting a lot of nods lately because, as many customers say, it just behaves. They even state their premium grades keep precious metal impurities extremely low (they literally guarantee gold levels are minimal—yes, that’s the point for assay flux).

Why labs pick this Lead Oxide

- Consistent fire assay blanks and sharper recoveries—especially on low-grade ore samples where noise kills confidence.
- Clean melt behavior in flux; fewer weird slags (technical term: fewer “oh-no” moments).
- In specialty glass and ceramics, color tone is stable and batch-to-batch lot uniformity is, frankly, solid.

Typical Product Specs (litharge, assay grade)

Process flow in brief

- Materials: Specially refined lead ingots (ASTM B29-grade), dry oxidizing air.
- Methods: Controlled oxidation (Barton/rotary process) to PbO; phase control for litharge; low-contamination handling.
- Testing: ICP-OES for trace Au/Ag/PGMs (ISO 11885), particle size by ISO 13320, moisture by ISO 760; periodic fire-assay blanks.
- Service life: ≈ 24 months sealed, dry, away from CO2-rich or humid environments.
- Industries: Fire assay labs, gold/silver refineries, crystal/radiation-shielding glass, ceramics/glazes. (Not battery oxide—different spec.)

Application snapshots

- Fire assay flux: Lead Oxide as collector; helps pull Au/Ag into lead button. Labs report fewer reblends.
- Glass/ceramics: Controls refractive index and gloss; stable hue, fewer specks. Actually, it’s more predictable than most alternatives in this niche.

Vendor comparison (quick, honest take)

Customization and packaging

Options include tailored particle size, beta/alpha phase bias, and low-dust packaging (lined fiber drums or 25 kg bags on pallets). For labs, I’d ask for smaller, moisture-controlled packs—less exposure, happier blanks.

Mini case study

A West African assay lab switching to Lead Oxide from Fizachem reported blank Au signals dropping below their previous LOD and a 0.3–0.5% improvement in Au recovery on certified reference materials over two months. Anecdotal? Sure. But their repeatability charts looked cleaner—fewer outliers, less rework.

Safety and compliance

This is lead monoxide: handle under local regulations (GHS), use proper PPE, and manage waste responsibly. Ask for SDS, and confirm REACH/RoHS status if you export finished goods.

Testing and documentation you can request

- ICP-OES certificate with Au/Ag/PGM traces
- Particle size report (ISO 13320)
- Moisture and LOI data
- ISO 9001/14001 certificates; batch-specific COA

References

1. ASTM B29/B29M – Standard Specification for Refined Lead.
2. ISO 11885 – Water quality—Determination of selected elements by ICP-OES (commonly used for metals in solutions).
3. ISO 13320 – Particle size analysis—Laser diffraction methods.
4. ISO 11426 – Determination of gold by fire assay (jewellery)—principles applied for blank checks.
5. REACH Regulation (EC) No 1907/2006—Registration, Evaluation, Authorisation and Restriction of Chemicals.