Cleaning seashells is simple and just takes some soaking, scrubbing, and drying. Use gentle methods first, and only move to stronger cleaners if needed.
Basic cleaning
Rinse shells in warm, soapy water (a few drops of dish soap) and gently scrub with an old toothbrush to remove sand, algae, and loose debris. Rinse well with clean water and let them air-dry completely on paper towels or a cloth.
Removing smell and residue
If shells still smell or have stubborn film, soak them in a diluted bleach solution, such as roughly 1 tablespoon of household bleach per gallon of water or a light 50/50 bleach–water rinse for a short time. Check every 10–30 minutes, then rinse thoroughly in fresh water and wash again with soapy water so no bleach remains.
Safety and shell protection
Use gloves, keep the area ventilated, and avoid strong bleach on very thin or nacreous shells (like abalone or pearl oyster), which can dull or damage them. Never mix bleach with other cleaners, and discard any solution safely down a well-flushed drain.
Optional shining and finishing
Once shells are fully dry, you can lightly buff them with a food-safe mineral oil to deepen color and give a gentle shine. For a more sealed, glossy look, some crafters use a clear acrylic spray, but it will make the finish more artificial than bare shell.