Silversmith Makers Reference Kit — Conversion, Solder, Annealing, Pickle, Patina
A five-tab bench reference: metal conversion, solder grades, annealing colors, pickle chemistry, and patina color charts. Print-friendly for a bench binder. Compiled from public technical literature and standard metalwork teaching texts.
Weight — grams ↔ troy ounces ↔ pennyweights
Edit any field to recalculate the others. 1 troy oz = 31.1035 g. 1 dwt (pennyweight) = 1/20 troy oz = 1.5552 g.
Volume ↔ mass (silver density 10.49 g/cm³)
Estimate the weight of a piece from its dimensions, or estimate volume from a weight reading.
Useful shortcuts:
- A cube 1 × 1 × 1 cm of solid silver weighs 10.49 g
- A disc 25.4 mm (1") × 1.5 mm weighs roughly 8.0 g
- Sterling density is slightly lower (~10.36 g/cm³) due to copper content
- Water-displacement measurement: weigh dry, weigh submerged, divide mass by difference = density
Wire reference (B&S / American wire gauge — used in US jewelry)
UK / European wire is specified by SWG or direct millimetre measurement. B&S 20 ≈ SWG 20 ≈ 0.81 mm.
Silver solder grades & flow temperatures
All five grades are silver alloys, differing in copper and zinc proportions that change the flow point. Work from highest flow to lowest across sequential joins.
| Grade | Flow °C | Flow °F | Typical use |
|---|---|---|---|
| Extra-easy | 681 | 1257 | Final closing join where no further soldering follows. Limited strength under stress. |
| Easy | 711 | 1311 | Second or third sequential joins. Most common grade for simple bezel and jump-ring work. |
| Medium | 749 | 1380 | General-purpose. First or intermediate joins in multi-step work. |
| Hard | 778 | 1432 | First join on a piece; heavy structural elements. Color matches sterling best after polishing. |
| Extra-hard (IT) | 804 | 1479 | Initial structural joins on complex assemblies. Closest color match to sterling. |
Flow temperatures aggregated from published technical data of Rio Grande, Hoover & Strong, and Stuller tool/supply catalogs; values differ ±5 °C between manufacturers.
Annealing temperatures & colors
Anneal to the stated color in a dimmed workspace — daylight makes the critical "dull red" invisible. Quench immediately in water or pickle (exception: Argentium — air-cool first, then quench).
| Alloy | Target °C | Target °F | Visible color (dim room) | Note |
|---|---|---|---|---|
| Fine silver 999 | 593 | 1099 | Dull red (dim room) | Most forgiving; quench immediately. |
| Sterling 925 | 593–649 | 1099–1200 | Dull red to light cherry (dim room) | Prevent firescale with Pripps or borax flux coat. |
| Britannia 958 | 593–621 | 1099–1150 | Dull red | Softer than sterling when annealed; shorter heat cycle. |
| Argentium 935 / 960 | 538–593 | 1000–1099 | Barely visible red (dim room) | Lower anneal temp; DO NOT quench while red — air cool to black, then water quench. Germanium needs slow cool-down. |
| Coin 900 | 593–649 | 1099–1200 | Dull red to cherry | More copper; tarnishes faster. Treat like sterling. |
Dim-room color cues (by approximate temperature)
- Very dark red (~480 °C) — below anneal
- Dull red (~550 °C) — Argentium and Britannia anneal zone
- Light cherry red (~600–650 °C) — sterling anneal zone
- Bright cherry red (~700 °C) — solder easy-grade flow
- Orange-yellow (~800+ °C) — too hot; silver will melt shortly
Pickle chemistry — three common recipes
| Recipe | Mixing ratio | Notes |
|---|---|---|
| Sodium bisulfate (Sparex) | 2 tbsp Sparex in 1 cup warm distilled water (≈55 °C) | Household: 95 parts water, 5 parts dry Sparex. Warm but NOT boiling. Change when green. |
| Citric acid (safer) | 1 part citric acid crystals : 8 parts warm water | Food-grade, non-toxic fumes. Slightly slower. Change every ~20 pieces or when yellow. |
| Alum (most gentle) | 1 part potassium alum : 16 parts warm water | Slowest but safest. Good for delicate Argentium work where Sparex can etch too aggressively. |
Chemistry at a glance
Sodium bisulfate (NaHSO₄) in warm water yields a mild sulfuric-acid bath that dissolves copper oxide and flux residue. Citric-acid pickle relies on organic-acid chelation of copper. Alum pickle uses aluminum-sulfate acidity.
The reaction with firescale:
CuO + 2 H⁺ → Cu²⁺ + H₂O — copper oxide dissolves, leaving behind silver.
Safety & disposal
- Wear safety glasses. Even a splash of warm Sparex in an eye requires immediate irrigation.
- Work in ventilation. Sparex vapor is a mild respiratory irritant over long exposure.
- NEVER use steel tweezers to drop a piece into Sparex. Copper ions in the bath react with steel and copper-plate every silver item present. Use brass, copper, titanium, or plastic-coated tools only.
- Neutralize spills with baking soda (sodium bicarbonate). Rinse the neutralized slurry with plenty of water.
- Spent pickle is NOT drain-safe. Neutralize with baking soda until bubbling stops, then precipitate copper out with galvanized (zinc) wire — the zinc replaces copper, which settles to the bottom. Discard the solid residue with your municipality's household hazardous waste scheme.
- Argentium NOTE: do not pickle Argentium while it is still red-hot — quench in water first, then pickle. Fresh Sparex can etch Argentium's germanium-oxide protective layer if used while very hot.
Patina chemistry & color chart
Each method produces a characteristic color sequence and requires different safety precautions. Test on scrap before committing to a finished piece.
| Method | Recipe | Color sequence | Control tip |
|---|---|---|---|
| Liver of sulfur — neutral (cool) | Pea-sized lump dissolved in 1 cup warm (≈50 °C) distilled water | Light gold → deepening yellow → purple → blue → black | Shorter dips = warmer colors. Rinse in clean water to stop reaction. Neutralize with dilute baking-soda bath. |
| Note: Highlights show through subsequent burnishing. Seal with microcrystalline wax to stabilize colors. | |||
| Liver of sulfur — hot | Same ratio, but bath at ≈60 °C | Skips gold/yellow stages — goes directly to deep blue-black. | Best for even all-over blackening. Avoid on fine details unless deep darkening is desired. |
| Note: Hot sulfur attacks harder; don't use on pieces with plique-à-jour enamel or pearls (sulfur damages both). | |||
| Ammonia fume | Sealed container, 25% ammonia solution in a shallow dish, piece suspended above for 6–24 hours | Blue-green to gray patinas — copper-bearing alloys (sterling, coin) only. Fine silver minimally affected. | Stop by removing and rinsing in clean water. Patina continues to darken for a few hours after removal — pull slightly early. |
| Note: Ventilation MANDATORY — concentrated ammonia vapor is a severe respiratory hazard. | |||
| Potash sulfide (hot) | Dry potassium polysulfide, same proportions as liver of sulfur but more alkaline | Similar to liver of sulfur but more blue-black emphasis on copper-rich alloys | Use immediately after mixing; alkaline solutions break down within days. |
| Note: Sterling + copper alloy work: gives deeper blue-black than liver of sulfur. | |||
| Selenium dioxide (hot) | Commercial gun blue solutions based on SeO₂; apply with brush | Deep gunmetal to near-black | Brush-applied for selective darkening. Wax-seal or it will wear off. |
| Note: Toxic — use gloves and ventilation. Not suitable for jewelry with prolonged skin contact. | |||
| Heat coloring (sterling only) | Clean, grease-free piece heated slowly with a soft flame | Pale yellow → amber → purple-red (~270 °C) → blue (~295 °C) → grey → black | Temperature controls color. Quench immediately to fix color. Practice on scrap — timing is tight. |
| Note: Fragile — easily scratched. Seal with lacquer or wax. Often used for Art Nouveau revival work. | |||
- Microcrystalline wax (Renaissance Wax) — warmest, renewable, jeweler-standard.
- Permalac Classic / Everbrite — lacquer sealants for harder-wear pieces.
- Kiln-fired low-temperature sealant — for enameled + patinated combinations.
Color sequences and temperature data from Richard Hughes & Michael Rowe, The Colouring, Bronzing and Patination of Metals (Thames & Hudson, 1982) — the standard reference in metalwork education.