Introduction: Sponging Up: Cleaning & Preserving Beachcombed Sponges

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We went beach combing on Sand Key Beach, on the Florida West Coast, recently, enjoying an unseasonably warm December day (at 80 degrees, warm even by Florida standards!). It was windy, making the usually calm Gulf of Mexico a bit choppy, which didn't help much with respect to shells, but did apparently stir up some sponge beds, making for a fun opportunity with the Gulf's leftovers!

We don't find sea sponges very often, but on the few past occasions we have, we've had little luck cleaning them - ending up with rather stinky, unusable brittle bits of organic matter that aren't very enjoyable to have around. This time, we thought we'd do a little more research on the subject to see if we could find a better way to clean and preserve them.

Commercial sea sponge harvesting, which is big industry up the road in Tarpon Springs, involves bringing in fresh seas sponges and essentially letting them rot, by leaving them in the water or covered with wet burlap until all the organic material in them has died off. Then the sponges are beaten, squeezed and rubbed to remove the dead material leaving only the sponge skeleton - the absorbent material we use on cars and dishes.

The process takes a while and is intended for large scale commercial ventures. We just wanted to clean four little sponges. So we took a slightly different approach to achieve what we hoped would be a similar end - clean and dry sea sponges we can use for decorative or utilitarian purposes. We think it worked!

Natural sponges can be used for a variety of different things, and make lovely gifts, good material for indoor gardening, and are useful for painting or cleaning,making these little beach finds a great repurposed treasure.

Step 1: Materials Needed

You'll need

  • Some beach combed sea sponges
  • A container for water
  • Eventually a little laundry detergent
  • A drying rack

Do not use bleach, vinegar, or any other harsh cleaning agents on your sea sponges. They're pretty sturdy, but bleach will ruin them.

We have three different types of sponges here, loosely identified as a little basket sponge, tube sponges and possibly something more Gorgonian (coral) in nature, for which this process also seemed to work. (I used Florent's Guide to the Florida, Bahamas and Caribbean Reefs to help ID our beach finds, which makes for fascinating browsing!)

Step 2: Rinse

Since we didn't harvest these fresh like commercial sponge fisherfolk do, we operated under the assumption that these had tumbled about a bit in the Gulf before they washed ashore and had been dead for a least a few hours, if not longer. During our beach combing, however, we avoided any sponges that already smelled bad - and rotting sponges smell very much like any rotting sea life. Sponges are living creatures until they're not, and if they lie around on a beach for a while, they don't smell very good.

Although the commercial practice is to let them rot, the ones that were rotting on the beach were not covered in water, as they are commercially, so we felt it best to stick to sponges that were pretty fresh out of the water.

We wrapped our sponges in wet paper towels from the beach restroom, and put them in plastic bags to keep them wet. Once home, we filled a plastic pitcher with tap water then squeezed the sponges repeatedly, agitating the water as we did so.

Step 3: And Repeat

As you can see, even little sponges hold a lot of material (hence, why they're so useful!) - after more than 8 rinses, dumping cloudy water each time and refilling the pitcher, the sea sponges gradually released less sand and debris.

Step 4: Soak Overnight

When the water was fairly clear, we let the sponges soak overnight.

Step 5: Rinse Again

The next day, we rinsed and squeezed the sponges several times again, until the water was pretty clear.

Step 6: Dry Outside

Press as much water as possible off your sponges and then set outside to dry for a day or two. We placed ours on an elevated grate so there was air circulation around the sponges, and covered them with a plastic flower pot that we weighted down with rock, since we have squirrels and wrens that take any interesting looking piece of material that might be remotely edible or useful in a nest.

Our sponges are pretty small and were completely dry the next day.

Step 7: Light Wash

Adapting recommendations from a sponge farming guide I found, I gave our little sponge(like) collection a light wash in fresh tap water with about a teaspoon of laundry detergent. I agitated the sponges lightly in the sudsy water. Even after all the previous rinsing, some additional material was still washed out of the sponges at this stage.

Step 8: Final Rinse

Then I rinsed thoroughly in clean tap water until the water was clear. By this time, all that handling had broken my larger, suspected soft coral, piece up a bit, but the sponges were fully intact.

Step 9: Dry Again

This time, we set our beach combing treasures out to dry on a covered patio. By the end of the day, they were dry again, with only a faint high tide seaside aroma, which will probably fade a bit more but never completely go away. If you've ever seen dried seahorses or other similar seaside fare in shops, you'll be able to smell that same scent there, as well.

For our purposes though, the process was a great success and we'll probably tweak a bit further in the future. Adding baking soda would probably help further with odor reduction, as well as removing any other organic material still in the sponges. The nice thing about sponges is - they're sponges! You can wet and rewet them as much as you'd like!

Step 10: Use & Enjoy!

You can do a lot of different things with natural sponges. The little basket sponge is perfect for indoor gardening, to display a small air plant. The tube sponges can also be used for air plants, or the soft coral piece can be used as an accent piece on three dimensional art, for a customized frame or other display. You can also use denser pieces of sponge for painting.


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