We use state-of-the-art German-made casting machinery, leaving nothing to chance. Flasks are held under vacuum while metals melt in an oxygen-free, argon-rich atmosphere, eliminating gas porosity and preventing oxidation.
During metal solidification, the flasks are vibrated at precise frequencies and durations, resulting in:
The outcome is castings with superior tension and elastic properties, easier to process, and in high-volume environments, up to 25% faster post-processing
At Hygrade Casting, quality is non-negotiable. We use the finest investment powders, water exceeding distilled standards, and top-tier mixing equipment from Germany and Italy to prepare flawless moulds.
Our proprietary 14-hour burnout cycle guarantees complete wax elimination and a clean, ash-free mould, producing precise, high-quality castings. We never compromise with rapid burnout cycles, every casting and flask is treated with the care it deserves.
Clients are welcomed to supply their own castable waxes: injection wax, hand-carved wax, or 3D-printed wax items. For injected waxes, please use a mould release spray (not baby powder) and premium-quality wax designed for jewellery with an ash content below 0.03%. Low-quality waxes containing plastics or oils can lead to porosity. Wax pieces must include a feeder sprue:
We accept customer-supplied rubber or silicone master moulds, ideal for high-volume clients reducing wax printing costs. Injection is charged at $5 + GST per pump (small–regular items) with a $25 + GST minimum for fewer than five pieces. We do not offer master mould-making services due to the complexity and time required.
We no longer accept customer-supplied resins, regardless of brand, cleaning and curing methods. All tested wax-like and castable resins produce inconsistent results, including miscasts, cracking, porosity, and sizing issues. Many clients have retired resin printing entirely, freeing workshop resources and avoiding ongoing headaches and have opted for us to handle 3D wax printing.
For standard trade-volume castings, we do not accept customer-supplied metals.
For high-volume clients, we offer flexible arrangements, including the option to supply your own pure gold as a float, allowing you to hedge exposure while maintaining consistent production. Terms and feasibility are discussed directly to ensure compliance, quality, and smooth workflow.
The table below provides key reference data, including wax-to-metal density factors and typical softening and melting points for common casting metals. Our 3D wax printing process has zero wax shrinkage, and for small to medium-sized pieces we routinely achieve casting shrinkage rates as low as 0.10%.
Where high precision is required, such as post-polish tolerances within ±0.10 mm or designs involving extensive benchwork, additional shrinkage allowance should be made for material removal during filing, sanding, and polishing.
For jewellers, the most critical value is the casting gravity (wax) factor, which determines the metal weight required to match a given wax model. These conversions are indicative and may vary slightly due to sprue length (minimised via flush-cut) and minor fluctuations in final alloy purity (e.g. 17.98K - 18.02K). Zinc burn-off during casting can marginally increase net gold purity, resulting in a slightly heavier finished piece.
| Material | Approximate Density | Casting Gravity Wax Factor | Softening (Approx) | Liquidous Melting (Approx) |
| 18 Karat White Gold (13% Palladium) | 16.11 g/cm³ | x 16.95 | 920 - 940 °C | 1,100 °C |
| 14 Karat White Gold (13% Palladium) | 14.46 g/cm³ | x 14.50 | 880 - 900 °C | 1,050 °C |
| 10 Karat White Gold (13% Palladium) | 13.84 g/cm³ | x 13.70 | 840 - 870 °C | 980 °C |
| 9 Karat White Gold (13% Palladium) | 11.81 g/cm³ | x 12.45 | 720 - 750 °C | 980 °C |
| 24 Karat Fine Gold | 19.32 g/cm³ | x 19.37 | 200 - 300 °C | 1,064 °C |
| 22 Karat Yellow Gold | 18.53 g/cm³ | x 18.15 | 400 - 500 °C | 1,040 °C |
| 18 Karat Yellow Gold | 15.38 g/cm³ | x 16.20 | 700 - 750 °C | 960 °C |
| 14 Karat Yellow Gold | 13.61 g/cm³ | x 12.95 | 860 - 880 °C | 940 °C |
| 10 Karat Yellow Gold | 13.03 g/cm³ | x 12.00 | 820 - 840 °C | 910 °C |
| 9 Karat Yellow Gold | 11.60 g/cm³ | x 11.70 | 800 - 820 °C | 880 °C |
| 22 Karat Rose Gold | 18.65 g/cm³ | x 17.80 | 1,000 - 1,020 °C | 1,040 °C |
| 18 Karat Rose Gold | 14.75 g/cm³ | x 15.55 | 890 - 900 °C | 950 °C |
| 14 Karat Rose Gold | 14.92 g/cm³ | x 14.00 | 860 - 870 °C | 930 °C |
| 10 Karat Rose Gold | 13.20 g/cm³ | x 12.60 | 820 - 830 °C | 900 °C |
| 9 Karat Rose Gold | 12.75 g/cm³ | x 11.90 | 800 - 810 °C | 870 °C |
| Ultra-Silver (5% Palladium) | 10.53 g/cm³ | x 10.90 | 850 - 860 °C | 980 °C |
| Fine Silver | 10.49 g/cm³ | x 10.70 | 730 - 740 °C | 960°C |
| Sterling Silver | 10.38 g/cm³ | x 10.55 | 820 - 830 °C | 890 °C |
Our 3D wax printers produce zero wax shrinkage. Through tightly controlled burnout cycles, flask and casting temperatures, and quenching times, we routinely achieve casting shrinkage as low as 0.50%.
In practice, additional allowance is often required due to surface finishing. 3D wax prints require sanding and polishing, and bench techniques can introduce further material removal. For designs requiring final tolerances within ±0.10 mm, we recommend factoring shrinkage into your STL files.
Recommended Shrinkage Allowances
If your wax model weighs 0.35 g and is to be cast in 18 karat white gold:
0.35 g (wax) × 16.95 (18K white gold wax gravity) = 5.93 g of 18K white gold
This figure is an estimate. Final cast weight may vary slightly due to natural wax density variation and minor zinc burn-off during casting, which can marginally increase final gold purity and weight.
Additional wax used for the main feeder sprue must also be accounted for. Sprue length varies with design requirements, tree positioning, and the need to prevent breakage during investment and pouring. After casting, feeder sprues are flush-cut using industrial pneumatic cutters, leaving a small section of sprue (typically 1–3 mm) attached to the piece.
For sprue and flow-gate design examples, please refer to our CAD Tech tab page.
For detailed guidance, please visit our CAD Tech page.
Gold purity is a sensitive subject in casting because true karat accuracy demands precision, discipline, and accountability, all of which cost money behind the scenes. We embrace that cost.
During casting, zinc naturally burns off, even under argon shielding. This causes a slight increase in gold purity, which is why our castings generally read no lower than the actual fineness (ie 18 karat generally reads 18.01K or higher on XRF scanners). This is not a fault, it is the outcome of tightly controlled, professional casting process. It can also result in a marginally heavier final piece, which is invoiced on actual post-cast weight.
Rather than “balancing” purity by adjusting zinc between melts (a common practice that risks falling below legal thresholds), we follow strict, repeatable protocols. Every melt is prepared using NMI trade-approved scales accurate to 0.001 g, calibrated with certified weights before every use. Under Australian law, 18 karat gold must contain a minimum of 74.58% pure gold (17.92 karat). Our castings consistently fall on or above the fineness (ie: 18.00-18.02+ karat) in real purity because we intentionally add 0.010 g of extra gold per 100 g melt. The cost to us is negligible; the assurance to our clients is absolute.
We do not rely on zinc loss to “push” borderline alloys into compliance. Gold and alloy components are weighed precisely to exact milligram values. If you ever encounter a reading such as 17.97K, this typically reflects scanner variance (not actual purity). NMI trade-approved XRF scanners have known built-in tolerances approved within them, placing a plum fineness (ie exactly 750 / 18 karat) can have different readings from XRF scanners:
Minor positional changes on XRF scanners as little as 1 mm will alter readings. This variability is normal, even in NATA-approved laboratories. To ensure consistency, a control ring is included in every flask, positioned centrally. After casting, it is cleaned, sanded, polished, and scanned. In addition every item is XRF scanned after post-processing to ensure all items are at or above the legal threshold.
All precious metals such as gold, silver, and palladium are sourced exclusively from accredited Australian bullion suppliers with full assay certification.
No scrap. No fillers. No shortcuts.
This is casting without compromise.
If you demand accuracy, traceability, and absolute consistency, from bespoke items to large production-scale runs, we are built to meet that standard.
