A pocketful of shells from a beach walk looks lovely on the sand and a little less lovely on the kitchen counter a day later. Sand, salt, algae, old barnacles and, sometimes, a smell you can detect from across the room are all part of bringing the shoreline home. Which method suits a shell depends on the shell, as the collectors' guides below explain.
This guide walks through the order that makes sense for most collectors: confirm the shell is legal and empty to take, remove anything still inside, rinse the outside, deal with crust and odor, and finish with a light touch if you want a bit of shine. Where shell collectors disagree, we say so, because the right method depends on the shell and on how much you value it.
Before you clean: is the shell yours to take?
Cleaning starts at the beach, not the sink. Two things are worth checking before you pick anything up.
Is the shell empty? A shell that looks abandoned can still hold a living animal. Beachcombing guidance warns that sand dollars, sea stars and sea urchins in particular should be dead before you take them home. The North Carolina Shell Club's collecting-ethics page adds that a living shell washed ashore is already dying, so tossing it back into the water is not an effective rescue, and it advises collecting conservatively rather than taking everything you find.
Are you allowed to collect here? Rules differ by location. In units of the U.S. National Park Service, the federal regulation at 36 CFR 2.1 generally prohibits gathering natural products, but it lets a park superintendent designate certain items, including unoccupied seashells, that visitors may gather by hand for personal use, with limits on size, quantity and place. The same regulation prohibits sale or commercial use of natural products. State parks, marine preserves and local beaches have their own rules, and some states require a fishing license to collect live shells from public waters. When in doubt, check with the park or local authority before you bag anything up.
What you will need
You do not need special equipment. A basic kit looks like this:
- Running water (a small water jet, or a large needle-free veterinary syringe, which the British club says is rumoured to work well, can help flush out remains)
- A dental pick for levering out remains and lifting crust
- A freezer, if you plan to use the freezing method
- Optional: mineral oil, baby oil or liquid paraffin for a finishing touch
- Optional, with caution: household bleach, rubber gloves and an open window
Step 1: Remove anything still inside
If there is any trace of the animal left, deal with it first. The British Shell Collectors' Club notes that the decomposition of even small traces of animal tissue causes a disproportionate smell.
Collectors use several approaches, and different guides favor different ones:
- Freezing. One guide suggests freezing the shell for at least a day, and preferably two to three, then thawing it slowly (no hot or boiling water, no direct sun). Another describes freezing in a sealed bag with water for a day or two, defrosting slowly and then levering the remains out with a dental pick.
- Boiling. The British Shell Collectors' Club describes putting the shell in water, bringing it gently to the boil for three or four minutes, lifting it out with a ladle and picking out the remains with a dental pick. Seashell-Collector.com says boiling will not damage murex shells (it suggests freezing, thawing and then boiling for them), and the same guide warns against putting a frozen shell into hot or boiling water while thawing. Neither guide says which other shells tolerate boiling, so check before you boil anything valuable.
- Flushing. After treatment, the British Shell Collectors' Club suggests a small water jet or a large veterinary syringe without a needle to flush out remains.
- Time and ants. Seashell-Collector.com suggests leaving the shell outdoors, hidden from the sunlight, for several days so ants clean it; the British Shell Collectors' Club describes burying it in sand beside an ants' nest for several weeks.
If a shell is rare, old or sentimental, the safest path is the mildest method that works. A local shell club is a good place to ask before you try anything stronger.
Step 2: Wash the outside
Once the animal is out, rinse the shell with water and let it dry; the collectors' guides we checked do not prescribe a soap soak, so this guide does not either. Outer skin and crust are covered in Step 3.
Take it slowly with glossy shells such as cowries. Seashell-Collector.com warns against leaving cowries and other polished shells in water with the animal still inside for more than a few minutes, because it can leave an irreversible rainbow-like ray on the back of a cowrie, and says bleach causes irreversible damage to naturally polished exteriors.
Step 3: Tackle crusty buildup
Barnacles, crusts and the thin outer skin some shells carry (called the periostracum, which the British Shell Collectors' Club describes as a woven jacket) can remain after the animal is out.
Some collectors soak stubborn shells in a diluted bleach solution. One collectors' guide describes soaking in a 50% solution of strong bleach and water for a couple of days to remove the outer skin, then picking off remaining crusts with a dental pick. Another describes pure bleach for periods ranging from several hours to a day or more for specific shell groups. These are not the same recipe, which is the point: there is no single agreed-upon strength or time.
If you decide to try bleach:
- Wear rubber gloves and eye protection, open windows and doors, and never mix bleach with ammonia or any other cleaner (CDC guidance).
- Keep it away from glossy shells such as cowries and olives, and do not use it on freshwater or land shells, according to the British Shell Collectors' Club.
- Rinse the shell and let it dry afterward; the British Shell Collectors' Club suggests draining it canal-down on sand or absorbent paper.
- Expect the outer skin (periostracum) to come off, which changes how the shell looks.
If you would rather skip bleach, a dental pick can be used to gently lift encrustations, though the guides we checked describe doing this after a bleach soak.
Step 4: Get rid of the smell
A smell that lingers can mean tissue is still inside. Go back to Step 1 and flush again.
Two fixes for stubborn odor are described by the collectors' guides: a very small amount of bleach left inside the shell for a day (Seashell-Collector.com), or soaking in alcohol (the British Shell Collectors' Club says for a couple of days; Seashell-Collector.com specifies at least 90% ethanol for naturally shiny shells). Both come from collectors' guides rather than conservation institutions, so try them on a shell you can afford to lose first.
Step 5: Add a little shine, if you like
A dry, dusty shell can look dull even when it is clean. The British Shell Collectors' Club suggests giving a dull shell a soft dust, then rubbing in a mineral or baby oil, removing the excess and drying it on absorbent tissue; it notes liquid paraffin evaporates more easily and many collectors use it. Two details matter:
- Only oil a fully dry shell. The British Shell Collectors' Club says plainly never to oil a damp shell, and Seashell-Collector.com says to let the shell dry before applying oil.
- Less is more. Make sure surplus oil does not stain your display case. On naturally polished shells, Seashell-Collector.com advises wiping off fingerprints, as leftover oil or grease may damage them.
Oiling is optional, so skip it on any shell you want to keep in its natural state.
Cleaning shells for decor
If your shells are headed for a bowl on the coffee table, a glass jar in the bathroom or a beach-themed centerpiece, once the animal is removed and the shell is rinsed and dry, display comes next. The British Shell Collectors' Club advises displaying shells away from strong sunlight, protecting them from UV light, and choosing a place with low humidity. If you like keeping small reminders of a trip or a season, our guide on how to press flowers covers another simple keepsake project, and our post on decluttering sentimental items without the guilt can help you decide which finds deserve a spot on the shelf.
Quick recap
- Check that the shell is empty and legal to collect.
- Remove any remaining tissue by a method suited to the shell: freezing, gentle boiling where a guide recommends it, flushing or letting ants do it.
- Keep glossy shells such as cowries and olives away from bleach, and never use it on freshwater or land shells.
- Wear gloves and eye protection with bleach, ventilate, and never mix it with other cleaners.
- A lingering smell can mean tissue is still inside.
- Oil only fully dry shells, and use very little.
Sources
- U.S. Code of Federal Regulations, 36 CFR 2.1, Preservation of natural, cultural and archeological resources (unoccupied seashells, superintendent designation, prohibitions): https://www.law.cornell.edu/cfr/text/36/2.1
- Beachcombing Magazine, "What the Shell? Identifying Seashells" (check that sand dollars, sea stars and sea urchins are dead before taking them home): https://beachcombingmagazine.com/blogs/news/what-the-shell-identifying-seashells
- North Carolina Shell Club, "Shell Collecting Ethics" (live shells washed ashore, conservative collecting, local regulations, fishing license note): https://ncshellclub.com/shell-collecting-ethics/
- Seashell-Collector.com, "Cleaning Seashells" (freezing, murex and boiling, bleach, polished shells, alcohol, ants, mineral oil): https://www.seashell-collector.com/beginners/cleaning.html
- British Shell Collectors' Club, "Cleaning and Maintaining Shells" (boiling, freezing, bleach and alcohol, flushing, oiling, odour, display): https://www.britishshellclub.org/cleaning-and-maintaining-shells.html
- CDC, "How to Safely Clean and Sanitize with Bleach" (gloves, eye protection, ventilation, never mix with ammonia or other cleaners): https://www.cdc.gov/natural-disasters/safety/how-to-safely-clean-and-sanitize-with-bleach.html
