Seashells are some of nature's most breathtaking jewels, although often they're found dull, crusted or dirty. Before using seashells as home decor or in crafts and jewelry making, you can bring out their true beauty by polishing them. It is best to try to only collect seashells that no longer have a living creature inside them.
Depending on the kind of shell that you are polishing, one method of cleaning or polishing might produce a better effect than another. This article includes a variety of methods for cleaning and polishing shells.
Cleaning Your Seashells
Before you can polish your shells, you need to clean them.
Step 1: Let the sunshine in
Set your seashells outside in a single layer for a few days, or even a few weeks. The sun will dry and bleach the shells in a rudimentary manner and cause the periostracum coating to start peeling off. However, this method works best with white shells rather than those with pretty colors, since the sun can bleach your shells white.
Step 2: Wash and scrub
Carefully wash your shells with soap and water. Then use a water jet to remove any leftover sea life from the interior of the shell. If you still have barnacles or other stubborn matter stuck to your shells, use a dental pick or descaling tool to gently remove them. You can also use a toothbrush or grill brush to scrub the shells.
Step 3: Boil and remove remnants
Disinfecting Your Seashells
Once your shells are clean, you need to disinfect them with alcohol or bleach to remove any lingering smells, organic matter or dirt.
Step 1: Soak in alcohol
If your shells have exteriors that are naturally shiny, such as cowries, olive snails or marginellas, using chemical bleach or acid on them can risk damaging the sheen. Fill a bucket or dish with enough 90-percent rubbing alcohol to cover the shells, and let them soak overnight.
Step 2: Soak in bleach solution
For most other shells, including clam shells, spiny oyster shells, cone snails, sea snails and conch shells, use a bleach solution to disinfect your shells and remove the remaining periostracum. 75 percent water and 25 percent bleach works well, but if you want more strength, you can use a 50-50 solution. Fill a bucket with enough solution to cover your shells, and gently place them in the liquid while wearing eye protection and rubber gloves. Let the shells soak for a few days, or at least 24 hours. Note that this method will sometimes turn your shells completely white -- if you don't want this result, use an acid dip instead.
Step 3: Dip in acid
Strong acids can burn your skin and eyes, and should not be inhaled. You must wear eye protection and gloves if you wish to use these chemicals, and perform the procedure in a well-ventilated area such as outside.
Shells like abalone shells, king's crown shells, snail shells and colored clam shells sometimes appear dull white after bleaching due to a calcium film left on the shell. If you have bleached your shells and think they're ruined, don't worry -- you can bring back the shine with muriatic acid. This process also works for shells that you prefer not to bleach because you want to keep the deep colors instead of risking the shell lightening.
First apply a layer of petroleum jelly to the inside of the shell, or any areas where shiny mother-of-pearl is exposed. This will protect the sheen from the acid. Then pour a few tablespoons of muriatic acid on the outside of the shell, and stand back while it starts to work. After a few minutes you can scrub the shell with a stiff brush -- make sure you're wearing protective gloves -- and then rinse thoroughly with a garden hose.
Conversely you can make an acid solution using 1 gallon of water and 1/2 gallon of muriatic acid. Use tongs to dip the shell into acid solution for three seconds, and then immediately dunk it into a water bath and rinse it with a hose.
Always put the water in first and add the acid to the water. This will avoid splashing which can be very dangerous.
Polishing Your Seashells
After your seashells are clean and disinfected, you can polish them to a high sheen that highlights their inner beauty.
Step 1: Remove hard water stains
If you have stains remaining on your shells after bleaching and disinfecting, you can remove them with a hard water stain removal product such as Lime-A-Way or CLR. Dip a stiff-bristled brush such as a toothbrush in a small amount of the product, and use the brush to scrub and polish the shell.
Step 2: Polish and buff
Use a sheet of fine-grade sandpaper to sand to buff the outside of your shell until it starts to shine. Finish bringing out the glossy finish with a nail buffer.
Step 3: Shine with acetone
If the inside of your shell is dull, you can make the mother-of-pearl gleam with a drop of acetone or nail polish remover. Simply rub the acetone on the shiny parts of your shell in a circular motion until it glimmers.
Step 4: Finish with oil
To add a final high gloss to your shell, use a mineral oil -- but not baby oil, since it can start smelling funny after a few weeks. Vitamin E oil also works well. Pour a small amount of oil on a doubled-over piece of paper towel and rub the oil onto the shell. Turn the shell and keep polishing with the lightly-oiled paper until the oil has all been absorbed by the shell.