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
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.
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.
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.
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.
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.
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.
Are the crystals stable?
Yes. Once you dry them properly, you can keep sugar crystals for a long time.
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.
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.
I highly recommend growing monoammonium phosphate crystals, they are among the easiest and fastest to grow. Check out my guide here.
If you want more exotic crystals, you can take a look at my articles on making black copper acetate crystals from scrap copper and vinegar, or blue copper sulfate crystals, which can be bought from gardening stores as rootkiller.
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. If you want to stay updated with more articles like this, consider signing up for my newsletter.
And as always, happy growing!