Did you know that you can grow transparent sugar crystals at home?
Hi! I’m Chase, a university student who’s been growing crystals at home for 3 years now. I’ve grown crystals from table salt, Epsom salt, fertilizer, and crystallized other colorful chemical compounds I made myself.
It’s a wonderful hobby, and I’m still amazed at just how many household materials you can make crystals from.
In this guide, I’ll share my procedure on how to grow sugar crystals. Most recipes online only teach you how to make rock candy, but you can do much, much more.
The article will be split into 3 parts:
- Part 1: How to make rock candy
- Part 2: How to grow chunky sugar crystals
- Part 3: How to grow a transparent single crystal
The idea is simple. Hot water can dissolve more sugar than cold water. What we want to do is to dissolve a huge amount of sugar in hot water. Then, once the solution cools down, the excess sugar is forced to “come back out”, and forms sugar crystals in the process.
All 3 parts use the same principle to grow crystals, but in each part, we tweak the procedure to make the sugar crystals grow in different ways.
Let’s get started.
How to grow sugar crystals
Materials
To grow sugar crystals, you’ll need:
- 6 cups of table sugar
- 2 cups of water
- A pot to dissolve the sugar
- A spoon
- A large jar
- Some wooden skewers
- Nylon fishing line
- A flat dish
Part 1: How to make rock candy
This is the easiest experiment to attempt. It’s a perfect activity for kids to make their own snack, because it’s very straightforward and gives results fast.
To start, get ready with 1 kg of fine white sugar. Coarse sugar also works, but fine sugar is better because it dissolves faster in water.
To your pot, add 3 cups of sugar per cup of water. Close the lid and heat the mixture until all the sugar dissolves. Stir the solution occasionally to speed up the process.
Initially, the solution will be cloudy. It should take no more than 10 minutes for it to clear up.
The solution has cleared up after 10 minutes.
When this happens, turn off the heat immediately to prevent the sugar from caramelizing. Then, cover the lid of the pot and let the pale yellow sugar solution cool to room temperature. It’s very important that you cover the lid of the pot, or else sugar crust will form on the surface of the solution as it cools.
When the solution has cooled completely, pour it into a large jar.
At this stage, you can choose to add food coloring and/or flavoring. Just add a few drops and mix it evenly with a spoon.
Next, dip a wooden skewer into the sticky sugar syrup. After that, take it out, and sprinkle some sugar grains onto the skewer until it is evenly coated.
Sugar grains are actually very small sugar crystals. The crystals that you sprinkle onto the skewer will act as seeds that grow into bigger sugar crystals.
Now, dip the sugar coated skewer back into the solution. You can either suspend it using some clips, poke some holes in a piece of cardboard to hold the skewer in place, or any other method you like. Just make sure that the tip of the skewer is at least 1 inch from the bottom.
This is what my setup looks like:
Leave it overnight.
The next day, a nice layer of sugar crystals will have formed on the skewers.
If you think they’re not big enough, just leave them inside for several more days.
By the 3rd day, my crystals had formed a nice, thick coating.
Remove the skewers from the solution, soak up the sugar solution on the crystals using a paper towel, and wipe them dry. And that’s it. You’ve successfully made rock candy!
Part 2: How to grow chunky sugar crystals
Maybe the crystals on rock candy aren’t big enough for you. Or maybe you’re a mineral enthusiast and you want more natural looking crystals. In this section, we’ll grow crystals like this:
To begin, prepare the sugar solution using the exact same procedure as above. After it has cooled, pour 50 mL of the syrup into a dish, while keeping the rest in a jar.
Sprinkle a few grains of sugar directly into the dish. Then, cut 20 cm of nylon fishing line, and tape one end of it onto stick. Poke the other end of the line into a dish.
The purpose of this step is to induce sugar crystals to form, and encourage a few of them to stick to the fishing line. Unlike the procedure for making rock candy, we don’t need the entire line to be coated with crystals – just one or two will do.
Leave the dish overnight, and this is what it looks like the next day:
Look at how a small cluster of sugar crystals have started growing on the fishing line.
Now, remove the fishing line from the dish, and suspend it (together with the crystals stuck onto the line) in the jar of sugar solution that you prepared previously.
Partially cover the top of the jar with some plastic wrap. This will prevent sugar crust from forming on the surface of the solution.
Place the setup somewhere nice and shady, and wait for the crystal to grow big!
This is what it looks like after a week:
You might also notice some wavy, distorted lines rising like heat waves from the top of the sugar crystal (see picture above). This is a sign that the crystal is growing rapidly. The effect is due to the deposition of excess sugar from the highly concentrated solution onto the crystal, causing the solution to become less dense and rise to the top.
At this point you can just sit back and relax.
When you think the crystal is big enough, take it out and dry it with a paper towel. Congrats, you’ve now got a huge chunky sugar crystal.
Very nice.
Part 3: How to grow a transparent single crystal
Let’s take it one step further.
It’s time for us to grow sugar crystals that look like gems.
In Part 2, recall that we poked the fishing line into the dish to let crystals form on it. Sometimes, if you’re very lucky, a single, perfect crystal will form on the fishing line.
Then, if you follow the previous procedure and suspend it in the sugar solution, it will grow into a nice, transparent single crystal:
However, it’s not always easy to ensure that just one crystal forms on the string. Most of the time you’ll get a bunch of them stuck together (like the one pictured in Part 2).
Since sugar crystals also like to form at the bottom of the container, you might be tempted to pick out a sugar crystal and tie it to a string. Indeed, most of the time, this is the standard procedure crystal growing procedure.
Clear sugar crystals like to form in the dish. Don’t be tempted to move or take them out. Touching them will cause sugar dust to form.
However, it will not work for growing sugar crystals. This is because the sugar solution is extremely supersaturated. If we so much as touch any crystal, we will chip it, releasing thousands of tiny particles into the solution, forming crystal dust.
This is what sugar dust looks like. It sticks to the otherwise transparent crystals and ruins them.
Therefore, here’s a more reliable method to grow a single crystalline gem from sugar.
Again, pour sugar solution into a dish. Make sure that the dish has a flat bottom. But this time, don’t sprinkle any sugar grains inside. Just let it sit somewhere quiet, like the basement, or the inside of a drawer.
Also, shield it from air movement (like the fan). If air constantly flows on the surface of the solution, it will cause crust to form on top, which is not what we want.
Eventually, small hexagonal crystals will start forming on the surface. How long it takes for them to appear depends a lot on luck – sometimes they pop up within 2 days, occasionally it can take 1 week.
Observe the small hexagonal crystal that formed in the middle of the dish.
Once you see a single crystal appear, use a spoon to scoop up some sugar solution, and drip it on top of the crystal to make it sink to the bottom. Note that by dripping solution on top to sink the crystal, we do not directly touch the crystal; thus, no crystalline dust will form.
We want to sink the sugar crystal because single crystals that grow on the surface will develop hollow cavities on the side facing up, which isn’t very nice.
After that, close the container/completely seal the dish with some plastic wrap. Sealing it this way will prevent further crystals from forming. This allows the single beautiful crystal to grow in isolation.
Since there are no other crystals around to compete with it, this crystal will grow faster than individual crystals in Parts 1 and 2.
Here’s the crystal after 1 week:
After 1 month:
Even though I sealed the dish, 2 other crystals also decided to form. But since they didn’t interfere with the growth of my original crystal, I just let them stay there. Besides, they looked quite pretty.
Like before, once you’re satisfied with their growth, you can take them out and dry them with a paper towel.
And that’s how you grow a transparent gem out of sugar!
Troubleshooting & FAQ
Growing sugar crystals is quite straightforward. However, in the event that you run into some complications, here’s how to fix them.
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Why did a fine sugar dust form in the solution?
Maybe it’s because you touched the crystals inside the supersaturated solution, shook them around, or hit the crystal hanging on the string against something. Unlike other crystals, sugar dust forms extremely easily – which is why my procedure in parts 2 and 3 above do not require you to touch the crystal in any way.
If the dust has already formed, you need to reheat the solution to get rid of it.
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Why did a layer of sugar crust form on the surface of the solution?
Sugar crust forms on the surface of the solution when the it evaporates too quickly due to excessive air movement. This is why I always recommend that you partially cover the top of the container with a lid, plastic wrap, or foil.
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Why are my crystals growing so slowly?
It takes some time for big sugar crystals to grow. Plus, crystals that grow more slowly are clearer and higher in quality.
Nevertheless, if you want to speed up the process, increase the ratio of sugar to water at the start, from 3:1 to 3.5:1.
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Can I use other types of sugar (cane sugar, brown sugar, etc.)?
There are a huge variety of sugars in the market. Granulated sugar, castor sugar and icing sugar are actually the same, they just come in different particle sizes. These sugars are white in color, which means they are relatively pure and good for crystal growing.
Cane sugar and brown sugar are less refined. You can also grow crystals from them, but the crystals will be yellow or brown.
Basically, you want to make sure that the sugar you use mainly consists of sucrose. Hence, maple syrup can be used (many people have observed crystals forming in their syrup by accident). But don’t use sugars like honey, which contains not sucrose, but fructose and glucose.
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Are the crystals stable?
Yes. Once you dry them properly, you can keep sugar crystals for a long time.
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Can the crystals be used for jewelry?
Nope. Sugar crystals are brittle and dissolve in water. I suppose you could seal one in epoxy, but I don’t think the effect will be very nice.
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What other crystals can I grow?
It’s amazing just how many different types of crystals you can grow at home. If you’re new to crystal growing, I recommend growing crystals from alum (used in baking) and monoammonium phosphate, a type of fertilizer.
Both are non-toxic and grow fast.
***
That’s all for this guide. If you have any questions, feel free to leave a comment below. If you enjoyed the guide, remember to share it with your friends.
As always, happy growing!
Hi Chase,
I just checked on my experiment after leaving it over night for the crystals to cling to the fishing line (i’m doing the cluster one) and the whole top layer of my solution is completely crusted; I can’t even pull the line out. And my leftover solution that is in the sealed jar is clear on the top half but the bottom kinda looks like solid sugar or something, even though it was completely clear last night. What happened and what should I do now? This is due in two weeks 🙁
The solution is too saturated (you added too much sugar). Try to dissolve about 10% less sugar next time. Alternatively, you can also dissolve the sugar crust + remaining syrup in 20% more hot water. Then try again.
Note that depending on the temperature at your place, the amount of sugar you need to dissolve might change. A colder room temperature you should dissolve less sugar, because its solubility is lower.
Hi Chase,
What’s the recommended amount of time to keep chunky sugar crystals in the shade? I was wondering how long you kept it for the final photo of the chunky sugar crystal tutorial.
Thank you!
About 2 weeks. Actually there’s no recommended amount of time. The longer you leave it inside, the larger the crystal will grow.
Hi Chase,
This is really awesome! I have a dumb question though.
When there are multiple crystal forming on the bottom of the container I cannot clean them because they will chip and release “dust”.
Then how can I harvest any crystal ever? If I try to harvest any crystal, it will chip too?
Harvest the crystal only when you’re satisfied with its size, that is, when you want to stop growing it.
doin this for science fair prolly gon mess it up
Have faith, good luck!!
Can I use this in cakes ??
Well, they’re technically edible – but don’t blame me if someone breaks their tooth lol
Can I add colors in solution to make color full crystals?
Yes. You’ll have to add a lot though, as the crystals aren’t easily colored.
Wow I never knew we could make rock candy at home I thought it was just made in factories.
Thanks chase for inspiring me to learn science and I’m a sixth grader well I hope you have a good day hope you gat the reply. Please send more totorials bye😁
Now you know 🙂
Have fun, and stay curious!
me too lol
Thank you for the tutorial! It was really easy to follow as a beginner. I was wondering if you can make borax crystals using this method? I want to try with sugar first to practice but would like to have crystal I can keep.
I’m glad you found it useful! Yes, borax works. However, the ratio of borax vs water will be different. It’s about 1 cup borax per 3 cups water. Good luck!
Hi Chase,
I am helping my son make crystals for a science fair project and after 24 hrs the sugar in the solution has settled in the lower 2/3 of the jar. The top 1/3 is transparent and looks like the pictures you’ve shown. The rest is almost solidified.
The solution in the dish with the fishing line is also very think and seems to have solidified.
Is it time to start over?
Looks like your solution was *too* saturated, so there was a huge excess of sugar inside that deposited as crystals, forming a very thick layer. Try using slightly less sugar next time.
If you have a lot of solution leftover, then just decant the solution to a new container and use this new solution to grow. If there’s not much left, then you’ll have to repeat the procedure.
I’m not sure why, I know my solution is sufficiently saturated… but my sugar crystals (making the second project) are taking forever to grow. Admittedly, I have a lot of crystals on the end of my string (far more than the 4-5 you have.), and I was wondering if that affects growth time.
Yes, the more crystals you have, the slower each of them grows on average. This problem gets worse if there are lots of crystals on the bottom that compete with those on the string. Try decanting the sugar solution into a new container, and move only the crystals on the string to the new container.
I tried to use distilled water and Fiji mineral water to make sugar crystal. I thought that the distilled water would make the largest, because it has no impurities. I found that the mineral water (Fiji) made almost the same size, sometimes slightly bigger. What would be the cause of this? any ideas?
In general, sugar crystals aren’t very sensitive to the type of water you use. Therefore, the size difference that you noticed is likely not due to the type of water you used, but random chance or fluctuations in either the crystal nucleation or the environment – stuff that’s hard to control.
Hi Chase! I will be making this experiment with 27 kids. Is 1 cup of water and 3 cups of sugar enough for one child? or will that ratio work for 2 kids? I am asking my kids to bring a 12-14oz mason jar, so each one can have their own skewer crystal.
Thank you!!!
Hello. 1 cup water and 3 cups sugar is enough for one person (it’s actually a bit more ~ but it’s always good to have a little extra on hand).
Hello Chase! My problem is this: I was trying to make the big, single crystal. After I prepared the supersaturared solution, I colored it and put it on a quiet drawer we never use. After a couple of days, I’ve found out not only a sugar crust has formed on top of the solution, but also hard sugar deposits are forming on the bottom! If I understood correctly, you only cover the solution with a lid or something else once the first small crystal has formed, right? Or maybe I should do it from the beginning, once the solution has cooled down? What about the hard sugar deposits on the bottom? I’m very confused 🙁
Hello. Don’t worry, it’s normal for the crust to form. This can happen when the air is too dry, or there is a lot of air movement. And once the crust forms, it might sink to form those deposits at the bottom. You can try reheating the solution to dissolve the crust, add then add a tiny bit of plain water at the top (without stirring) so that the surface will not become too saturated too quickly. This should discourage crust from forming.
Cover the solution with the lid while it is still hot. The hot water vapor will dissolve unwanted crust. Wait a day or so before reopening the lid to enable evaporation, and thus allow fewer, but better individual seed crystals form.
Hello, what do i do with the extra solution while i wait for my crystal to form?
Just leave it tightly sealed in a jar to prevent stray crystals from forming.
Hi Chase! Love your site. We’re working on a science fair project and want to try your method exactly. You don’t specify if you bring the solution to a boil. Should we or shouldn’t we?
Thanks! The main point is to dissolve all the sugar. Whether or not the water boils doesn’t matter, though it might dissolve a bit faster in boiling water.
that’s what I’m going for sciences fair and it look nice and really cool
Good luck and have fun 🙂
Hey! Can I add a bit of look aid powder for flavor ?
Yup, sure.
Hi! If I don’t have fishing wire, could I use thread or string?
Thanks!
Sure. Expect more crystals to stick on the thread, because it has a rougher surface. It’s perfect for making crystal clusters, but not so great if you want to grow single crystals.
good but all your “how to’s” are hard to understand. how ’bout making them easier to read?
I have tried making them as easy to read as possible. Any suggestions?
Your instructions are fine. I think he is lazy… 🤷
😂
Hey Chase! Come from the Reddit! Amazing work! Is there anyway to make crystals form that are not hexagonal without using a fishing wire? Also what happens if you introduce a single sugar crystal of your desired shape into the solution. Is there anyway to do that without creating Sugar Dust?
Thanks! At the bottom of the solution, there’s basically two orientations in which the sugar crystals will form. One of them looks flat and rectangular, and the other one looks hexagonal. If you use a fishing wire, you get a crystal that is well formed on both orientations, which means that if you look at a crystal that looks rectangular from another angle, it will look like a hexagon.
Yes, you can introduce a single sugar crystal into the solution. However, it must be done without any physical contact to prevent sugar dust from forming. Try scooping some solution containing a small sugar crystal floating at the top, or using a dropper to transfer solution containing a small crystal suspended inside.
There are some special type off sugar, like big grain rock sugar that was already a pretty big single pieces. Can I use that to skip early steps and add one to the solution and grown it instead?
Sure, that works too.
Hello, I covered the lid but there is crust on the surface forming anyways.
If i just manualy remove the crust will it still work ?
If not, is there any other ways to stop crust from forming ?
Don’t physically remove the crust. If you do so, the entire solution will be filled with microscopic sugar dust. Instead, warm the solution to around 70C for 30 minutes. This will get rid of the crust. To prevent new crust from forming, add a few drops of water to the top of the solution (without mixing it evenly), then seal the container. This will dilute the sugar solution on the surface and discourage crust formation.
How do I get one single crystal to grow on the fishing line. I got to the small dish part and a single crystal grew on the bottom so I used a fork to dislodge it and kind of balance it on the fishing line but it never stayed there because the crystal was slowly sinking in the solution while the fishing line slowly ascended in the solution. and the fork movement created crystal dust which encrusted everything. So do i just have to be super patient and have a crystal grow on the line, and if so how do I get rid any extra crystals that grow beside my chosen one on the fishing line?
I try to use a crystal, sometimes 2 crystals to “press down” on the fishing line so that the line doesn’t ascend. If this doesn’t work, you can also purposely make crystal dust, which will form throughout the solution. Wait a few hours for some of the dust to settle; there should still be a good amount of dust in the solution. Then poke the fishing line inside and a few grains of dust should stick to it. Your last option is to just tie a crystal to the line. It won’t be as pretty, but you’ll get results.
Any suggestions insofar as what to do with the leftover solution? Do you reuse it ever by adding it to a new batch?
Yup, that’s exactly what I do.
Thanks for these fantastic instructions! Do you know the ratio of sugar:water by weight? I’m doing this on a large scale with a class.
250 g sugar per 100 mL water. The accuracy is not very important; you just need to be somewhere within that range.
Edit : Shining a light into the solution reveals that they are tiny tiny crystals.
Hi Chase,
I’ve made up a concentrated sugar solution and poured a small amount off into a dish, where I’ve also put some fishing line for the crystals to adhere to.
My problem is with the larger portion of the solution. While it was cooling down in the saucepan (covered with a lid) a crust formed on the surface so I reheated it until the crust melted back into solution.
Once the now-cooled-again solution was poured into a larger jar and covered with cling wrap I can see what looks to be 1000’s of tiny bubbles. Will these affect any subsequent crystal growing, or are they in fact tiny sugar crystals coming back out of solution? Any advice is very much appreciated.
Hey Dave,
The tiny tiny bubbles are just bubbles, and they form in my solutions immediately after pouring/transferring too. They do not interfere with crystal growth and are nothing to worry about. The bubbles will disappear within 1 week.
Edit: The situation changes if they are tiny crystals. Just stick the fishing line into the solution; some of the crystalline dust should stick to the fishing line, and start growing bigger on it.
If you want to grow big single crystals at the bottom of the container instead, you will have to wait 3-4 days for the tiny crystals to get bigger. As they grow, they get heavier and sink to the bottom of the solution, leaving the top pristine. So all you have to do is to decant the sugar solution at the top into a new container to start your growing process.
Hello! How do you prevent mold from growing? I feel like I’ve done crappy version in the past when I was in elementary school (grad school now) but I feel like I always ended up with mold too
Nevermind! I’ve found my answer in another comment–just wasn’t patient enough. I guess my childhood versions weren’t hypertonic enough, so I’ll make sure I make a really strong concentration this time around 😁
Are these lolipops safe to eat? Won’t water with a ton of sugar grow bacteria very fast?
Yes, they are safe to eat. A highly concentrated sugar solution actually acts as a preservative, *stopping* the growth of bacteria. This is due to something called osmosis, in which the sugar draws the water out of bacteria so that they can no longer grow. People apply sugar as a treatment for wounds, and to preserve food.
nice work, came from redidit
Hi, fellow Redditor 🙂
This process is so cool. Looks like you have really perfected and worked hard on this.
Thank you! I love what I do, and sharing the process allows me to give others an opportunity to discover a hobby they might like too.
Thanks a lot, I’ve really been looking forward to this
Very cool project.
How can we speed up the process a little bit?
Can’t we play with temperature of the solution while the crystal is forming (particularly in part2 and 3)?
By lowering it the water’s solubility drops and encourages the sugar to form solid particles.
Yeah, you can. Even slight temperature changes will significantly increase the growth rate, which is great if you want to grow them fast. But note that the crystals will also be less clear because of the rapid and usually disorderly growth.