Numismatics — the most delicate area
Cleaning coins is the most challenging application for an ultrasonic cleaner. The reason: unlike jewelry (where shine = value), in numismatics, natural patina = authenticity = collector value.
A wrong decision to clean can lower a coin's value by 30-70%. A 19th-century Polish silver coin with natural patina worth 5,000 PLN, after aggressive cleaning, might be worth 2,000-3,500 PLN.
The decision: to clean or not to clean?
Before the first cycle, ask yourself these questions:
1. Coin age
- <30 years (1990+) — clean on your own, Vitaclean ultrasonic cleaner concentrate is OK
- 30-100 years (1924-1990) — think it over, some PRL coins are better kept with patina
- >100 years (before 1924) — never clean on your own, consult a conservator
2. Coin value
- Circulating coins worth a few zlotys — clean without worry
- NBP commemorative coins (50-500 PLN) — clean with moderation
- Appraised collector coins (1000+ PLN) — consult before any cleaning
- Antiques, archaeological finds — always consult a conservator
3. Material
- Copper-nickel alloy (5 PLN, 1 PLN) — safe, Vitaclean ultrasonic cleaner concentrate is OK
- Stainless steel (1 gr, 2 gr newer) — safe
- Brass (older NBP 10 PLN, 50 gr) — Vitaclean ultrasonic cleaner concentrate is OK, but copper patina is something more
- Bronze (historical medals) — patina is crucial, DO NOT clean on your own
- Silver (silver PRL 1 PLN, commemorative coins) — Vitaclean ultrasonic cleaner concentrate is OK + optional polishing
- Investment gold — Vitaclean ultrasonic cleaner concentrate is OK, not sensitive
- Alloyed gold (thin gold on a core) — proceed with caution
Procedure — modern circulating coins
What you need
- Vitaclean ultrasonic cleaner concentrate — 15 ml + 600 ml of lukewarm water (1:40)
- Ultrasonic cleaner 600+ ml
- Tweezers or rubber gloves (do not touch coins with your fingers — grease returns)
- Microfiber cloth for drying
Procedure
- Pour into the cleaner: 15 ml Vitaclean ultrasonic cleaner concentrate + 600 ml lukewarm water
- Place coins in the basket — single layers, do not overlap (as they will scratch)
- Cycle 5-10 minutes (10 min for heavily soiled)
- Remove with tweezers — not fingers
- Rinse under running distilled water (if you have it) or filtered water (regular water leaves minerals)
- Dry with a microfiber cloth — do not rub, only gently dab
- Place in individual capsules (Leuchtturm, Schulz) — contact with air causes re-patination
Time: 10-15 min for 10-15 coins. Cost: less than 0.60 PLN.
What NOT to do
❌ Toothpaste — abrasive, destroys coin details (eagles, coats of arms) ❌ Coca-Cola (popular myth) — phosphoric acid is weak, but it leaves a sticky residue ❌ Undiluted 8% vinegar — aggressive, destroys details ❌ Strong detergents (Cif, Domestos) — dyes in the products may leave a trace film ❌ Bleach — destroys patina, stains some alloys ❌ Aluminum foil + soda (myth for silver) — works on black silver, but is aggressive on details and changes the surface ❌ Cleaning under a tap with a brush — scratches details, collector value drops ❌ Patina removal from truly valuable coins — loss of 30-70% of value
Comparison: Vitaclean ultrasonic cleaner concentrate vs. alternatives
| Method | Effectiveness | Safe for details | Price/cycle |
|---|---|---|---|
| Vitaclean ultrasonic cleaner concentrate + ultrasonic cleaner | 80% (grease, dust) | ✅ yes | less than 0.60 PLN |
| Professional conservator | 95% (with value preservation) | ✅ | 50-200 PLN / coin |
| Silver polishing paste | 70% (black silver) | ⚠ scratches details | ~30 PLN / 100 g |
| Soap + water | 50% (fresh grease) | ✅ | ~0.30 PLN |
| Toothpaste (myth) | 30% | ❌ scratches | NO |
| Coca-Cola (myth) | 20% | ⚠ stickiness | NO |
Special types of coins
Gold bullion coins
Krugerrand (South Africa), American Eagle, Canadian Maple Leaf, Vienna Philharmonic — safe in Vitaclean ultrasonic cleaner concentrate, 5 min cycle. 999.9 (24K) gold is chemically inert — it does not patinate. Vitaclean ultrasonic cleaner concentrate removes only external dirt (finger grease, dust).
IMPORTANT: gold bullion coins have a value dependent on weight and purity — cleaning does not reduce their value (aside from the risk of scratching if you touch them with your fingers).
NBP commemorative silver coins
The Polish NBP issues commemorative silver coins (50 PLN, 100 PLN, 200 PLN). Material: 925 silver. They develop a black patina over the years due to sulfur in the air.
Procedure: Vitaclean ultrasonic cleaner concentrate, 5-minute cycle + silver polish (Hagerty Silver Foam, Goddard's Silver Cleaner) ~30 PLN/bottle. After the cycle and polish, the coin regains its luster.
Value: The nominal value of NBP silver issues is relatively low, and cleaning does not significantly affect their collector value. However, for older silver coins (pre-2000), it may have an impact.
Old Polish coins (Second Polish Republic, early People's Republic of Poland)
Second Polish Republic (1918-1939): silver 1 PLN, 2 PLN, 5 PLN, 10 PLN coins have increasing collector value. Natural patina = authenticity. DO NOT clean them yourself using the Vitaclean ultrasonic cleaner concentrate — consult the PTN (Polish Numismatic Society).
Early People's Republic of Poland (1949-1980): small change, low value, can be cleaned.
Late People's Republic of Poland (1980-1990): commemorative value, circulation cleaning is OK.
Foreign coins (eurocents, dollars, pounds)
Safe — use Vitaclean ultrasonic cleaner concentrate for 5 minutes. Materials are similar to Polish ones (alloys, steel). Patina on cents usually adds collector value, but for coins in circulation = low value, cleaning is OK.
Historical coins / antiques
ABSOLUTELY NOT by yourself. Procedure:
- Conservator of monuments — Provincial Conservator of Monuments + PTN numismatist
- Expert appraisal of value and material
- Professional cleaning in laboratory conditions (controlled pH, time, temperature)
- Documentation of the process
Cost: 50-500 PLN / coin depending on difficulty. Required for everything found in the ground/archaeological finds (LAW).
Frequency
Private collection (amateur collector)
- Contemporary: Vitaclean ultrasonic cleaner concentrate cycle once every 1-2 years (no more often — contemporary patina forms slowly)
- Old: DO NOT clean at all, leave it to a conservator
- Investment gold: after touching with fingers (grease marks) — immediate 5-minute cycle
Gold investor
- After each contact with the coin (authenticity verification, weighing): 5-minute Vitaclean ultrasonic cleaner concentrate cycle
- Storage in capsules after the cycle — minimize contact with air
Numismatic shop
- Each new batch (from a customer or buyout): consult a conservator before cleaning
- Contemporary: Vitaclean ultrasonic cleaner concentrate cycle for presentation (capsule after cycle)
- NBP commemorative: Vitaclean ultrasonic cleaner concentrate + silver polish when customer requests "fresh look"
Most common mistakes
Cleaning everything together — a valuable coin can be damaged by contact with less valuable ones. Sort by material and age.
Skipping value check — Allegro: check similar coins, current listings. Catawiki, Heritage Auctions — international prices. You might have something more valuable than you think.
Toothpaste — a popular myth. It destroys details with scratches.
Pouring 100% Vitaclean concentrate — a 1:40 ratio is mandatory.
60+ min cycle — overkill. 5-10 minutes is sufficient for the vast majority of cases.
Cleaning with fingers — grease returns immediately. Use tweezers, rubber gloves.
Drying with paper towels — it will scratch details. Use microfiber gently.
Storing loose after cycle — patina returns in 1-2 years. Use Leuchtturm capsules, Schulz holders.
Related articles
- Ultrasonic cleaner — complete guide
- Cleaning jewelry in an ultrasonic cleaner
- Watches in an ultrasonic cleaner
Related products
- Vitaclean ultrasonic cleaner concentrate — 1L concentrate — for contemporary coins and circulating numismatics
Sources
- SDS Safety Data Sheet for Vitaclean ultrasonic cleaner concentrate (PDF)
- Polish Numismatic Society — coin cleaning guidelines
