Make Sea Glass in a Rock Tumbler–It Really Works!

Yes, you can 100% make sea glass in a rock tumbler.

Yes, you can 100% make sea glass in a rock tumbler.

On the CAGW Facebook page a few weeks ago, I expressed my intention to try to make “sea glass” (ie. tumbled glass) in my kid’s rock tumbler, as soon as she finished the batch of rocks that she was currently polishing in there.

Many of you responded to this declaration with something along the lines of “OMG PLZ TELL ME IF IT WORKS OMG GASP OPEN-MOUNTED EMOJI OMG!!!1!!!!”

Based on these comments, I’m feeling like you want me to tell you how my experiment went.

Result: It. Was. AWESOME!!!

Yes, you can 100% make sea glass in a rock tumbler. It’s super easy, and it comes out straight-up looking like sea glass. Here’s how to do it.

How to Make Sea Glass in a Rock Tumbler

You will need:

rock tumbler. You want a good-quality metal one, something along the lines of the Thumler’s Tumbler that we own. Good rock tumblers are pricey, but they make a great gift for a science-minded kid, so much so that if you don’t have a science-minded kid of your own, someone you know probably has one and may in fact have a rock tumbler that you can borrow.

filler. This takes up the spaces between the glass pieces. You can use either ceramic media or plastic beads, both of which can be re-used.

coarse grit. Unlike rock tumbling, which requires coarse grit, fine grit, pre-polish, and polish, making sea glass in a rock tumbler only calls for coarse grit.

broken glass. You don’t want anything too thin, like microscope slides, because the rock tumbler will abrade it so that it’s too thin to be useful. I had great luck with vintage glass bottles, however.

hammer and towel. Gotta break that glass somehow!

tile nippersThese aren’t necessary, but if you want to shape or trim your glass at all, you need them.

sea glass in a rock tumbler

1. Break some glass. As I mentioned before, I’m using vintage glass bottles to make sea glass, because that’s what I have a million of and need to find more things to do with. I’m primarily choosing either the glass bottles that were broken when I found them, or that are of unimportant provenance. I clean up and polish the nice vintage glass bottles and display them around my house, even though I’ve frankly got too many of those, as well.

ANYWAY… my preferred method of breaking a glass bottle is to wrap it in a towel, set it on my driveway, then whack it with a hammer. From the mess of broken glass, I pick out the nice pieces that I want to tumble. I really like bottle necks and bottle bottoms (ahem…), and also the side pieces if they’ve broken into a shape that I think will look nice when tumbled.

Use the tile nippers to trim a piece of broken glass into a more interesting shape, or chip off the edges around a bottle’s bottom.

2. Set up the rock tumbler. Use these instructions to make your tumbled glass. Note, however, that the instructions explicitly tell you not to use glass bottles. My experience is that you can, although you still want to avoid any glass that’s too thin. A Coca-Cola bottle should work. A spaghetti sauce jar probably won’t.

sea glass in a rock tumbler

3. Check your work. When you open up your rock tumbler after five or so days, the inside will look like this:

sea glass in a rock tumbler

Instead of sifting out the tumbled glass, I pick it out of the matrix and examine it. A couple of times, a piece has cracked and needs to be set aside. Sometimes, a piece is perfect just the way that it is and I love it. Most times, though, the tumbled piece is almost perfect, but still needs some refining. For that, get the tile nippers back out.

For instance, after examining that bottle neck in the above photograph, I decided that I’d like it better if it was trimmed even closer to the edge, so I did:

sea glass in a rock tumbler

4. Go for round #2. Pop any glass that you’ve trimmed, and enough new pieces to maintain the level in your tumbler, back into the barrel with the same grit and filler material. Give it a go for another five or so days, and then take a look. Repeat until you’re happy!

You can use your DIY sea glass for any projects that call for the real deal.

Written by Julie Finn

I'm a writer, crafter, Zombie Preparedness Planner, and homeschooling momma of two kids who will hopefully someday transition into using their genius for good, not the evil machinations and mess-making in which they currently indulge. I'm interested in recycling and nature crafts, food security, STEM education, and the DIY lifestyle, however it's manifested--making myself some underwear out of T-shirts? Done it. Teaching myself guitar? Doing it right now.

Visit my blog Craft Knife for a peek at our very weird handmade homeschool life; my etsy shop Pumpkin+Bear for a truly odd number of rainbow-themed beeswax pretties; and my for links to articles about poverty, educational politics, and this famous cat who lives in my neighborhood.

11 Comments

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  1. wow really interesting read Julie , i never thought it could be possible!

    Good tip Mark , i am planning to test it myself, and i will make sure that the glass should be thick enough to survive against the brutal otherwise it will shatter

    • Yip, that will work. However, I just used sand, water, and in about six hours – you will have good results. You might not even need to break the bottles – as the mixer will do that. If possible, use thick wine bottles – because, the thin beer bottles will crush into fine gravel or disappear altogether. — Rob

  2. What if we want to use wine bottles? Would we use a finer sand so they don’t break? All the glass in the tumbler would be the same thickness and similar size, so would that work, or would it break into smaller pieces?

  3. Where do I buy a durable rock tumbler? I’ve seen posted that the ones at Hobby Lobby are not very durable. Are you familiar to the ones at Hobby Lobby?

  4. Hi, thanks for sharing, just be careful not to inhale any of the dust produced – silica dust can cause silicosis – a lung disease, water is your best friend in terms of cleaning equipment and preventing dust going airborne.

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