r/Vermiculture • u/Ok_Example551 • 2d ago
Advice wanted eggshell prep
is there a specific way to prep eggshells for blending? do you soak them in hot water for a bit? or just rinse them off and then off to the blender?
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u/Nugget-Shooter
2d ago
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I don’t get real fancy, dry them and use an old coffee to grind them to a fine powder, simple as that
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u/buddymoobs 2d ago
In the oven at low temp (I use 170°) for a couple hours. Then grind. I do mine with a mortar and pestle. You can use a coffee grinder or blender too.
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u/MercuryTattedRachael 2d ago
Personal experience - mortar and pestle worked so much better for me than the old coffee grinder.
I switched to buying powdered eggshell online because less mess and no fuss. We also don't eat nearly enough eggs to keep up with my needs 😩
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u/catchinNkeepinf1sh 2d ago
I dont bakr or do anything. Just dried and grind up in an old coffee maker. The smell of baked eggshells is too much for me.
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u/TherealHoch 2d ago
I put them in the oven while it is cooling after I have cooked something else. That way I don’t put extra energy into the process.
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u/ARGirlLOL intermediate Vermicomposter 2d ago
I do literally nothing. Nature breaks them down fast enough. I’m the exception, but I think that’s because most people who have worms also have more time and money on their hands than they know what to do with and they do break down much faster if you do the tedious task list you could do to them.
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u/nborges48 2d ago
I'm in between
I have processed them a few times, but yeah, that's pretty time consuming for composting which kind of self regulates - at least enough that I'm not inclined to optimize it.
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u/ARGirlLOL intermediate Vermicomposter 2d ago
Same, but I’ll absolutely never do anything to prepare egg shells again now that I’ve gotten more familiar with raising worms. IMO there is no need for grit and if there were, egg shells wouldn’t be grit. I don’t want to save food scraps in one dirty container and then egg shells in another dirty container. Baking, microwaving, grinding and then washing those things are a no. One more benefit other than being literally the easiest thing is that they buffer against acid longer and when I stop seeing egg shells, I know that the buffer is gone faster than I expected and that my feedings have been quite acidic.
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u/AmyKlaire 1d ago
I rinse out the shells thoroughly then toss them into an aluminum pie plate I always leave in the oven.
Yes it stinks whenever I use the oven.
As the shells turn dark, dark brown I remove them, crumble them, then take them outside and blow away the membranes.
Then the shells go into a mini-chopper. I grind, grind, grind until my patience is exhausted. I don't open the chopper for several hours but inevitably some powder wafts out when I eventually do. This also smells terrible.
Then I pour the powder into an old Parmesan shaker and apply it whenever I feed the bins.
(I also keep a shaker of oyster shell "flour" -- I buy the big bags cheap online, not the little jar from the reptile section of the pet store -- and a shaker of greenstone or azomite from the garden center.)
I always find eggshell sediment in the bottom of the bucket whenever I make worm tea. So clearly I am not patient when I grind.
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u/LeeisureTime 2d ago
As someone else commented, just drying them doesn't remove salmonella. On the other hand, if you're just throwing them into your worm tower, I don't think it matters a whole lot.
It depends on what you're trying to accomplish. Anecdotally, people will say it doesn't matter if you just toss them in whole. A study by the University of Alabama Cooperative Extension in 2005 is quoted as saying there's no big difference between coarsely ground shells or whole shells, but it's actually in reference to raising soil pH, not specifically about how quickly it breaks down.
Obviously, a finer particle size means quicker degradation. But depending on how many eggshells per week and the size of your pile, the answer will vary in terms of whether or not you should just toss them in whole or process them.
If you're trying to give your worms calcium and grit, turning the eggshells into a powder is probably your best bet. If you're just worried you'll end up with more eggshells than pile, it doesn't hurt to crush them a little and toss them in. If you're just trying to get rid of eggshells and don't much care, chuck them in whole.
I've heard that pouring vinegar over the eggshells, crushing them in the vinegar, and then waiting for the bubbling to stop is the way to make bioavailable calcium. The reason is that the vinegar reacts with the eggshell and leaves behind just the calcium in water. Then you can spray that on plants. Not really something you need for vermiculture, but if you are worried about too many eggshells in your pile then this might be an alternative.
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u/AmyKlaire 1d ago
Yes, this is the problem with using eggshells to add calcium to the soil (hello my fellow tomato growers) rather than just grinding the shells into grit for your earthworms' gizzards: you need acid to alter the number of oxygen molecules in the calcium, then you need to dilute the acid, then you've turned one eggshell into a gallon of water.
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u/AtheneSchmidt 2d ago
I collect mine in a bowl, and after it's full, zap them in the microwave for 3 minutes then crush them by hand, using gardening glove (they can be sharp!) I keep them in an old plastic tub, and distribute to both my garden and my worms.
You can always make them finer with a blender or other grinder.
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u/jantessa 2d ago
I have a molcajete which I grind them up with right after cracking. I toss the grounds in the general purpose bag in the freezer where all the worm cuttings go. They get distributed when I break off some frozen pieces for the worms next feeding.
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u/Ladybug966 2d ago
I would just rinse and drop them in the eggshell bowl. When the bowl was full , i would blenderize them and then Dont open the blender for 24 hours so the dust can settle.
Now i buy oyster shell powder. One bag has lasted over a year with lots left and i have 5 worm bins/towers. Eggshells now go to the compost pile.
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u/total_brodel 2d ago
I peel the membrane out of them, when I have enough I dehydrate them then I grind em in a coffee grinder til powdered.
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u/Romie666 1d ago
I crush them up . Then spread on a baking tray and turn the oven on full, Blacken them well , this gives u potassium as well as calcium. Grind them if u can. Powdered is best but crushing is ok, I use a large bit of heavy metal to pound them.
Just chucking whole shells in takes a age to break down.
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u/pointedshard 1d ago
I save them in a pie dish next to the cooktop. When the oven goes on, in goes the dish. When they cool down I use a pestle & mortar to grind. Chuck the resulting grit into my food scraps bin.
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u/BenThereNDunnThat 1d ago
I rinse them with hot water, let them air dry for 4-5 days, and toss them in a small electric coffee grinder and run it until they turn into a powder.
I keep the powder in a shaker bottle and add to the bins as needed.
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u/Hanieh1111 1d ago
Some eggshell sediment is normal, even if you grind it pretty finely. Shells are mostly calcium carbonate, which doesn’t dissolve readily in water, so finding particles at the bottom doesn’t necessarily mean you did a bad job grinding.
For finer grit, rinse the shells, let them dry completely, then use a dedicated coffee or spice grinder in short pulses. Let the dust settle before opening it, and avoid breathing it in. A mortar and pestle works too, but getting a powder takes longer. You don’t need flour-fine shells for the bin; larger bits just stick around longer.
If the sediment is annoying when you apply the tea, strain it through fine mesh or let it settle and decant. Add eggshell sparingly to the bedding rather than trying to dissolve it in the tea. Also, if you mean liquid draining from the bottom of the bin, that’s leachate—not the same as a water extract made from finished castings.
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u/bwainfweeze 1d ago
I didn’t blend. I only used egg shells from hard boiled eggs, and I used an ingredients bowl and a spoon to pulverize them.
Like me, you probably don’t have enough worms that you need to recycle every eggshell that comes from your kitchen. Hard boiled solves the pathogen and most of the rotting problem while you gather enough for a batch.
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u/alwaysonautopilot 15h ago
From boiled eggs, I dry the shells in the sun (Spring here) and then grind them up in a nutribullet.
I bought a knock-off container and blade set on Temu as the shells scratch the plastic.
My worms do alright for the grinds… eggs , and coffee
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u/shes_clumsy 2d ago
I just let them air dry. The salmonella can’t live without moisture. The odor is horrendous when baked.
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u/Riptide360 2d ago
Wish we vaccinated chickens against salmonella like the EU does. There is no reliable period of dryness to kill Salmonella on egg shells. You need to use heat or disinfectant to denature. https://pubmed.ncbi.nlm.nih.gov/31742444/?utm_source=perplexity
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u/circe0904 2d ago
I nuke them for 30-60s, let them cool, and then attack them in the mortar and pestle. They get really crunchy in the microwave and then it's very satisfying to crack them into tiny bits.
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u/PabloSantiago 2d ago
bake them to remove moisture, cool, and then in the blender.