Have you ever noticed that there is a handful of copper coins in your grandmother's or neighbors' refrigerator? Or have you yourself heard the advice to put a “piglet” on the bottom of the chamber to “remove the smell”? At first glance, this looks like a superstition - they say, “they did it this way before, and everything was fine.” But behind this habit there is scientific basiswhich is confirmed even by manufacturers of household appliances. In the article we will look at which coins work bestwhere exactly to place them, and why this method sometimes loses to modern odor absorbers.
Spoiler: we are not talking about magic, but about chemical properties of metals. Copper and silver have an antibacterial effect, and their ions inhibit mold growth and neutralize volatile compounds that cause unpleasant odors. But there are nuances: not all coins are equally useful, and in some cases they can even accelerate corrosion of refrigerator parts - service center engineers warn about this. Next is a detailed guide with tables, warnings and answers to frequently asked questions.
Why coins: the chemistry of the process
It's all about redox reactions. Copper and its alloys (for example, in Soviet “kopecks” or modern 10-ruble coins) upon contact with moisture and oxygen form ions Cu²⁺that:
- 🧪 Destroy cell membranes bacteria and fungi (including mold Aspergillus and Penicillium —frequent “guests” of refrigerators).
- 🌬️ Neutralize hydrogen sulfide and ammonia - the main culprits of the “rotten” smell from meat, fish and dairy products.
- 💧 Binding excess moisture, reducing condensation on the walls (but does not replace defrosting!).
Interesting fact: this principle is used in professional antibacterial coatings for medical refrigerators. For example, in models Lieberr and Panasonic Premium the internal panels are covered with a copper alloy - but there the metal is sprayed at the molecular level, and does not lie in pieces.
However, there is a downside: if coins be placed incorrectly, they can:
- 🔋 Oxidize too quickly, becoming covered with a green coating (these are copper salts - harmless, but unaesthetic).
- ⚡ Conduct current upon contact with metal shelves (risk of short short circuit is minimal, but theoretically possible).
- 🧲 Interact with magnetic seals doors (relevant for old models of refrigerators ZIL or Minsk).
Which coins are suitable (and which are not)
Not all coins are equally useful. Efficiency depends on alloy composition i year of issue (modern coins are often coated with nickel, which blocks copper ions. The table below shows the ranking in descending order). usefulness:
| Coin type | Composition | Efficiency | Notes |
|---|---|---|---|
| Soviet 1-5 kopecks (until 1961) | 97% copper, 3% zinc | ⭐⭐⭐⭐⭐ | The best option. They oxidize heavily - require cleaning every 2-3 months. |
| Soviet 1-5 kopecks (1961–1991) | 92% copper, 8% aluminum | ⭐⭐⭐⭐ | Less active, but more durable. Oxidation is weak. |
| Russian 10 rubles (bimetal, 1997–2016) gg.) | Ring: copper+nickel, center: copper+zinc | ⭐⭐⭐ | Only the outer ring works. The effect is weaker than that of pure copper. |
| Eurocents (1, 2, 5 cents) | 94% steel, 6% copper (coating) | ⭐⭐ | There is little sense - the copper layer is too thin. |
| Modern 1-5 rubles (since 2017) | Steel with nickel coating | ⭐ | Almost useless. packages. |
Important: coins from aluminum (for example, some foreign small denominations) or nickel not only do not help, but may increase corrosion metal parts of the refrigerator Also avoid coins with strong oxidation - green coating (CuCO₃) may come into contact with food.
Where to put coins: optimal zones
Placement affects the result no less than the composition of the coins. Ideal points:
- Tray for collecting condensate (if it removable). Coins are immersed in water - this enhances ion exchange. Suitable for models Atlant, Indesit with a drip system.
- Back wall (on a plastic shelf or under an egg tray) The main thing is not to block the ventilation holes (in refrigerators). data-i="131">this is critical!). No Frost this is critical!).
- In a container with soda. Copper enhances the absorption of odors. Recipe: 2 tablespoons of soda + 3-4 copper coins in a gauze bag.
Where NOT to put:
- 🚫 On metal shelves - risk of galvanic corrosion (especially in refrigerators Samsung or LG with aluminum coating).
- 🚫 In the freezer —at low temperatures, the oxidation of copper almost stops.
- 🚫 Near fermented milk products —copper ions can accelerate the souring of kefir or yogurt.
Why you can’t put coins in the freezer?
At temperatures below –5°C, water in the air freezes, and the oxidative reactions of copper practically stop. In addition, condensation rarely forms in the freezer, so the main “target” for coins (moisture + bacteria) is absent.
Coins vs modern odor absorbers: what better
Manufacturers of household chemicals do not like the “old-fashioned” method - and for good reason. Let's compare coins with popular alternatives:
| Method | Pros | Cons | Cost |
|---|---|---|---|
| Coins (copper) | Durability (up to 1 year), antibacterial effect, does not require replacement | Needs to be cleaned, can oxidize, does not remove strong odors (for example, from fish) | 0 rub. (if you have it at home) |
| Carbon absorbers (Filtero, Zepter) | Absorb 90% of odors, no oxidation, can be reactivated in the sun | Require replacement every 2-3 months, do not kill bacteria | 200–500 rub. |
| Gel fresheners (Air Wick, Ambi Pur) | Quick effect, pleasant aroma, compact | Mask odors, but do not eliminate the cause; can be absorbed into products | 150–300 rub. |
| Ionizers (Xiaomi Smartmi) | Kill bacteria and mold, work automatically | Expensive, require power, can dry the air | 2000–5000 rub. |
Output: coins win in cost-effectiveness and antibacterial effect, but lose in speed of action and versatility. The optimal option is combine methods. For example:
- 🍎 For fruits/vegetables: coins + package with soda.
- 🥩 For meat/fish: charcoal absorber + coins on the bottom shelf.
- 🧀 For cheeses/sausages: gel freshener + coins in the back.
Dangers and warnings: what 90% of users do not know
Even such a harmless method has hidden risks. Here's what they don't tell in "folk" advice:
⚠️ Attention! If in your refrigerator aluminum shelves (often found in models Beko or Vestfrost), copper can cause data-i="195">. Signs: white powdery coating on the shelves, rapid rusting of the metal. In this case, use coins galvanic corrosion. Signs: white powdery coating on the shelves, rapid rusting of the metal. In this case, use coins only in plastic containers.
Other risks:
- 🧪 Copper ion poisoning. Theoretically, it is possible if the coins come into contact with acidic foods (for example, marinade). In reality, to do this you need to eat kilograms of such food - but it is better to play it safe and keep coins away from open containers.
- 🔌 Warranty problems. Some service centers (for example Bosch or Siemens) may refuse warranty repairs if they find “foreign metal objects” inside the refrigerator. This only applies to new models (up to 2 years).
- 🐭 Attracting rodents. Mice and rats instinctively collect shiny objects. If there are rodents in the house, coins can become “bait.”
How to minimize risks:
Place coins in a gauze bag or silicone case|Clean coins from oxides once every 2 months|Do not place coins on bare metal|Keep away from children's hands (risk of ingestion)|Check door seals for damage (copper oxides can corrode them)-->
Alternative metals: silver, zinc, aluminum
Copper is not the only option. Other metals also have useful properties, but with nuances:
- 🥈 Silver (cutlery, coins before 1961): it suppresses bacteria more strongly than copper, but oxidizes faster and is more expensive. Suitable for short-term use (for example, before the holidays).
- ⚡ Zinc (nuts, washers): cheap, but ineffective. Can be used as an addition to copper.
- ♻️ Aluminium (foil, cans): useless against odors, but absorbs moisture. Sometimes they put crumpled foil on the bottom of the refrigerator - this reduces condensation, but does not remove odors.
Experiment: in 2020, the magazine "Household and everyday life" conducted a test with different metals in refrigerators Atlant i Samsung. Results:
- Copper reduced the number of bacteria by 78% in 2 weeks.
- Silver - by 92%, but after a month the efficiency dropped to 60% (due to strong oxidation).
- Zinc and aluminum showed results worse than 20%.
Conclusion: for long-term use copper is optimal, and silver should be used periodically (for example, once a season).
FAQ: answers to frequently asked questions
Can foreign coins (dollars, euros) be used?
Most modern foreign coins are made from low-content alloys copper (for example, American cents - 97.5% zinc + 2.5% copper). They are practically useless. The exception is old coins (before the 1980s), where copper predominated.
How many coins should you put in?
3-5 pieces are enough (for a refrigerator with a capacity of up to 200 liters). More is not better: too much copper can accelerate corrosion of parts. Coins are not needed for freezers - there are no conditions for oxidation.
How to clean coins from oxides?
Methods:
- Vinegar + salt: soak for 10 minutes, brush with a toothbrush.
- Lemon juice: rub with a slice of lemon, rinse with water.
- Ketchup: apply for 5 minutes, rinse (no joke - the acid of tomatoes dissolves oxides!).
Do not use abrasives (sand, soda powder) - they scratch the metal and speed up further oxidation.
Is it true that coins help against mold?
Yes, but only on early stage. If the mold is already visible to the naked eye (black or green spots), the coins will not be saved - a general cleaning is needed. Copper prevents bleach or hydrogen peroxide. Copper prevents appearance mold, but does not remove it.
Can coins be placed in a refrigerator with a No Frost system?
Yes, but with reservations:
- Do not place coins in the ventilation holes (this interferes with air circulation).
- In models with plasma ionization (for example, Panasonic NR-BN) coins are redundant - the system itself copes with bacteria.
- If the refrigerator is with carbon filter (as in Liebherr), coins can be added to enhance the effect.
If you still have doubts, test the method in practice: put 2-3 copper coins for a week and compare the smell before/after. And if the refrigerator is old and “smells of history,” perhaps it’s time to think about choosing a new model with an antibacterial coating.