METHODS FOR CLEANING SILVER
Silver in the ground often gets covered with sulfides (blackening) or chlorides (horn silver).
Method 1: Alkaline cleaning (baking soda)
The gentlest method. The patina is preserved.
- Use a metal pot, water, and baking soda — soak the coin
- Bring to a boil
- Take it out every 5 minutes to check if dirt is coming off
- Brush it under running water
Method 2: Citric acid
- Add crystalline citric acid or lemon juice to water
- Soak for 5–7 days, brushing it every day
Method 3: Ammonia
- Soak for a couple of hours
- **Caution:** it can open up cavities hidden under the oxides!
Method 4: Thiourea (for black patina)
A professional-grade product. Dissolves only silver sulfide.
- Dissolve in hot (not boiling) water
- Concentration: 1–2 teaspoons (light) up to a supersaturated solution (for fully black coins)
- Add acid (phosphoric or citric)
- Optional: 30–40 g of vodka per glass — speeds up the reaction
- Average time: 15+ hours for a fully black coin
⚠️ Toxic — wear gloves and work in a ventilated area!
Method 5: Foil + baking soda + boiling water
- Boiling water, baking soda, and aluminum foil
- Place the coin in — triggers a reduction reaction
- Cleans very quickly