If you want to start collecting seashells, starfish and other pretty sea creatures, you should know how to clean and preserve them.

Cleaning Live Seashells

There are various methods that you can use to clean seashells and preserve them, such as the following:

• Burying

Look for a space in your yard where you can dig a hole up to 18” down and bury the shells. It should be deep enough to prevent animals from digging them up and to keep their fishy smell buried with them. Burying them will also allow the insects, larvae, ants, bacteria, and worms to remove all the remaining tissue in the shell and polish the inside of that shell. However, you would have to wait for months for the process to be completed.

An alternative would be to put the shell near an ant bed. However, you would have to endure the bad smell despite having only a few shells. This method will also put your little shells at risk of getting damaged when stomped or played around by animals. Just make sure to have your shells covered while the ants do their work, which should only take a few days to a few weeks at most.

But before burying or putting them near the ants, wash the shells inside out with a vinegar and water solution. Follow it up with a warm soapy water solution. Then, rinse the shells with fresh water and let them dry. Bleach them, a process that will be explained later.

• Freezing

Freezing Seashells

Look for a watertight bag and put the shells in it, then put the bag in a container and fill it with water. Put the container in the freezer and leave it to freeze solid, usually for 24 hours. Let them thaw if you want to start cleaning them. After defrosting them, let the critter out of the shell. Soak the shells in a vinegar and water solution, wash them with warm soapy water, and rinse them clean. Then, bleach them.

• Boiling

Put the seashells in a pot large enough to contain all of them. Fill it with water until the shells are covered with at least two inches of water over them. Let the water boil for a few minutes. The larger and the more shells you have, the longer it should boil. A fist-sized shell should be boiled for around five minutes and two of such shells should be boiled for eight. But a big batch of shells should be boiled for 20 to 25 minutes. Do not overdo it to an hour.

Remove the shells from the pot with tongs and gloves, then pull the critter out. Make sure it does not come apart to ensure a clean inner shell. Do the vinegar/water soak and wash the shells with warm soapy water. Rinse them, then bleach them.

• Bleaching

This is not applicable to all kinds of seashells. For one, don’t bleach Cowrie shells, Margellidae shells, Conus shells, and other naturally polished shells because it will damage the shells’ natural beautiful finish. Instead, use alcohol, which will be explained later. 

Before cleaning shells with bleach, make sure that they are tissue-free. Soak the shells in pure bleach. The soaking time varies based on the quantity and type of shells. You can mix all types during the bleaching process. Remove them only when their periostracum is completely gone. This is the flaky leather-like covering found on most live shells. In some shells, the periostracum is thick, which means it is harder and longer for the bleach to eat away. Carefully monitor the shells to spot those without their periostracum and take them out of the solution.

During the process, use eye protection, a rubber apron, and rubber gloves. Bleach can cause serious damage if not handled properly. 

Once the soaking is done, rinse the seashells with fresh water or brush the remaining periostracum away, if there is any. Use a soft wire brush or a toothbrush. You can let the shells shine once more with baby oil.

Let the shells dry for a few days. Afterwards, spray them with satin finish polyurethane or clear gloss, although satin gives them a more natural look. The right finish will keep the shells cleaner and prevent them from catching dust so easily. It also stops the shells from accumulating skin oil even if they are frequently handled, hence preserving them.

• Alcohol cleaning

Naturally polished shells, such as Conus and Cowrie shells, should only be cleaned with alcohol, not bleach, to protect their exterior surface. Soak them in 90% pure alcohol, Ehtanol, to remove the detritus inside and out. If alcohol can’t completely remove the bad smell, pour a small amount of bleach into the shell’s opening. Make sure not to spill it to its surface. You would know which shells are damaged because it will show as a rainbow-like effect on the bottom.

Don’t soak shells with a critter in them for more than a minute. If you smell decay, it means there are still critters remaining inside so you have to get it all out. Use a water pick to blast the remains out or let the bugs and ants do their work. Once the critter is removed, do the alcohol rinse again.

Cleaning Dead Seashells

If your shells still have coral or calcium in them, brush it off with a handheld wire brush or a small electric drill. You can even create a fun pattern on the shell by leaving some of the deposits out. Use a very fine wet 600 to 1200 grit sandpaper to polish the shells.

To remove barnacles, soak them in bleach. If there is still some left, use a dental pick, a toothbrush, a water pick, or a grill brush.

For rough lips, use a file or a rotary grinder to create a smoother lip on the shell.

If you want to make your seashells shine, wipe them with baby oil or mineral oil. You may also spray them with a satin finish or clear gloss.

Cleaning and Preserving Starfish

70% Isopropyl Alcohol

Clean the starfish by soaking it in a 70% Isopropyl Alcohol solution. Leave it overnight, although a bigger starfish, such as a Bermuda Star, should be soaked for two nights. After soaking, let it dry by putting it out in the sun or by using paper towels. Make sure to put the legs down to stop them from curling up when they dry.

Have fun in cleaning, preserving, and collecting seashells and starfish with these tips.