What is SHG zinc?
SHG · Special High Grade
Zinc of 99.995% minimum purity, the standard grade for galvanising and die-casting, specified under ASTM B6. Anything below this is a lower commercial grade and prices differently.
Key points
- 99.995% minimum zinc, defined in ASTM B6.
- The deliverable grade against LME zinc contracts.
- Lower grades are legitimate for brass, and price at a discount.
At a glance
| Full name | Special High Grade |
|---|---|
| Minimum purity | 99.995% Zn |
| Standard | ASTM B6 |
| Main uses | Hot-dip galvanising, die-casting alloys |
| Lower grades | High Grade ~99.95%, Prime Western below that |
The grade
Special High Grade zinc is refined zinc of 99.995% minimum purity, defined in ASTM B6 and the reference quality for LME zinc contracts. Lead, cadmium and iron are each capped in the low tens of parts per million.
It is the grade the market means when it says “zinc” without qualification, which is why a quotation for zinc at a discount to LME usually indicates something other than SHG.
What it is used for
Roughly half of world zinc goes into galvanising, where purity matters because impurities affect coating adhesion and appearance. SHG is also the feed for zinc die-casting alloys such as Zamak, where consistency governs dimensional stability.
For brass making, lower grades can be acceptable because the zinc is alloyed with copper in any case, which is why High Grade and Prime Western zinc still trade.
Where grade shows up commercially
The practical significance is that SHG carries the LME reference price plus a physical premium, while lower grades trade at discounts that vary by region and end use.
A contract should name the standard, not just the words. “SHG per ASTM B6, 99.995% min Zn” is enforceable; “high grade zinc” is not.
Frequently asked questions
- What purity is SHG zinc?
- 99.995% minimum zinc, with tightly capped lead, cadmium and iron, as specified in ASTM B6.
- What is SHG zinc used for?
- Mainly hot-dip galvanising and die-casting alloys, where impurities would affect coating quality or dimensional stability. It is also the deliverable grade against LME zinc contracts.
- How does SHG differ from High Grade zinc?
- Purity. High Grade is around 99.95% and Prime Western lower still. Both trade at discounts to SHG and are acceptable for uses such as brass making where the zinc is alloyed anyway.
Related terms
The benchmark primary aluminium grade: 99.7% minimum aluminium with tightly capped iron and silicon. The reference quality behind most LME-linked aluminium ingot contracts.
The analytical determination of metal content in an ore, concentrate or refined product. Buyer and seller assays commonly differ slightly; contracts usually set a tolerance and appoint an umpire laboratory to settle disputes beyond it.
The pricing reference for base metals including aluminium, copper, zinc and tin. Most physical contracts are written as the LME cash or three-month price plus or minus a negotiated premium reflecting grade, location and delivery terms.
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