Introduction: How to Grow Salt Crystals!
Growing salt crystals on objects to make interesting art forms or for a simple science experiment is easy and fun! Here I'll share how to grow crystals on 3D printed lattices and structures, but you can grow crystals on most anything you can imagine... or just on themselves.
This process is easy and only takes about 1 hour of active preparation and work, and a few days to grow.
If you're doing this as an introductory science experiment, growing crystal demonstrates how solutions are made and how the crystalline shapes of salt is formed. It is fun and fascinating to watch!
I embarked on this experiment to find out if I could guide the shape of the crystals to grow in a certain formation or size based on a lattice structure that I grew them on. Here's how I did it:
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Step 1: Supplies
To grow your own salt crystals you’ll need:
Crystals can be grown from almost any salt, however, for best results I suggest using copper sulfate or magnesium sulfate (epsom salt). You can also experiment with sodium chloride (table salt), sea salt, pink salt, etc. If you use copper sulfate, use nitrile gloves when handling.
I’m using Epsom Salt for this Instructable.
- Distilled Water
- Clean Container at least 2 inches around larger than what you are growing salt onto.
Clear containers are visually interesting so you can easily watch what’s growing, and using cook wear is the best option, as they generally retain heat and will not break.
- Object to grow crystals on or a string.
Experiment with lattice structures like I did if you'd like!
- Something to suspend your object in solution: sticks, chop sticks, wire, string, or a stand etc.
- Cooking Pot large enough to boil the right amount of water and salt for your project.
- Stirring Spoon
Step 2: Make Salt Solution
- Measure out water:
- Place your object in your container.
- Pour water into your container with object to figure out about how much water you will need.
- Then pour that water into a measuring container to evaluate how much water you've measured.
(I used a 12 cup measuring cup)
(a saturated solution is a little under 30% salt)
Step 3: Suspend Object or String in Salt Solution
To Grow Salt Alone:
- Place a stick or spoon across the center top of your container.
- Tie a string in the center of that stick that hangs down into the solution 1 1/2 inches off of the bottom of container or more.
- Leave the container where it will not be disturbed and watch your crystals grow
Growing Salt on an Object:
Similar to the above method, suspend or tie your object to the string so it is suspended in the solution with at least 2 inches of solution between the object and the container it is growing in.
Alternatively, you may suspend your object in the solution by using sticks or wire.
Since my structures were lattices, I used chop sticks to suspend the objects in solution, as well as hanging with wire.
Step 4: Wait for Your Crystals to Grow!
Do not disturb your container, but check in on your crystal growth often.
I suggest leaving your crystals to grow for at least 1 day, but you can leave it up to 3 days for greater results. There is a certain point where the majority of salt is used and crystals will not grow any larger.
Step 5: Gently Remove Your Crystals From Solution
Gently remove your string or piece out of the solution when you feel like your crystals have grown to a desired shape and size. If crystals have connected between the container to your piece, use a butter knife to gently release the crystals from the edge of the container, taking caution not to disturb the form you are growing.
Step 6: Want Bigger Crystals?
Before removing the string or object with crystals from its method of suspension, evaluate it and determine if you'd like to grow larger crystals. If you'd like larger crystals, you can repeat this process and continue to grow the crystals larger. You will have to make a new salt solution every time.
If repeating the process to grow larger crystals, the very important difference is after boiling and making salt solution to LET THE WATER COOL TO ROOM TEMP before re-submerging your string or piece.
If you do not do this, the hot water will melt the crystals that you grew and it will be like starting over.
Step 7: Samples
Here are photos of crystals that I grew over 3 solutions, check out the difference in size of the crystals.
I achieved the gradient effect by submerging the lattice deeper every time I put it in solution.
Step 8: Enjoy Your Crystals!
Once you have grown your crystals to the desired size, gently remove your string/object from its method of suspension. Let your piece dry on a towel. ENJOY!
For future experiments, you may try using tap vs distilled water, colored water, and try using different types of salt including iodized salt, un-iodized salt, sea salt, or even salt substitutes. What are the difference in the crystals?
You may further explore your crystals in a microscope!
Also, what do you notice by growing crystals on different structures?
I was surprised to find that the crystals grown on the white 3D powder print made of different size lattices grew different size crystals on each level.
Thank you to the Pier 9 3D Print Lab for giving me broken 3D prints to experiment with. This powder print was originally mathematically designed and made by John Edmark for his fascinating Blooms project.
Learn how to make them yourself in his Blooms: Phi-Based Strobe Animated Sculptures Instructable
Step 9: EXPERIMENT, SHARE WHAT YOU GROW & HAVE FUN!
Step 10: More Information on Crystal Growth
Here's more info on growing crystals from http://nobel.scas.bcit.ca/ to inform your interest and experiments!
The study of crystals and their structure is a field called Crystallography. A crystal is a solid that consists of the various atoms, or molecules being arranged in a uniform repeating pattern based on its unique shape. This results in the material having a specific shape and colour, and having other characteristic properties. Crystals may be big or little, but they all have the same "shape". Take a look at the display of crystals in the lab. Salt and sugar are examples of crystals. Table salt is NaCl and has a cube-shaped structure. Snow crystals form a six-sided structure. Diamond (used in jewelery, and cutting tools) is also an example of a crystal; it is made of pure carbon. Graphite (used in pencils and lubricants) is also a crystal made from carbon.
How are crystals grown?
In a solution, a solvent (water) can only hold a certain amount of solute. This is called thesolubility of a solution. When the temperature of the solution is increased, hot water can dissolve more solid substance than cold water. This is because heated water molecules move farther apart, making room for more solid substance to dissolve. When no more of the solid substance can be dissolved, the solution is said to be saturated. As this solution cools, the water molecules move closer together again and there's less room for the solution to hold onto as much of the dissolved solid. Crystals begin to form and build on one another as the water lets go of the excess solute. This process is called recrystallization and, depending upon conditions, one may obtain a mass of many small crystals or one large crystal.
How do crystals form and how do we control its rate of growth?
In this experiment, you will be growing crystals from a saturated solution. During recrystallization, crystals start growing by a process called "nucleation". Particles of dust on the surface of the solution can initiate crystalization. However, this situation is somewhat uncontrolled. To get controlled growth, a "seed crystal" is tied on a piece of thread and is submerged in the solution. As the temperature of the solution continues to drop, more crystals will accumulate on the thread. The rate at which crystallization occurs will affect crystal quality. The best crystals are the ones that grow SLOWLY.
Crystal - A crystal is a solid with a definite geometric shape. The shape consists of smooth, flat surfaces that meet in sharp edges or corners.
Crystallography - A branch of Chemistry that studies crystals and their structure.
Nucleation - When solute molecules in a saturated solution encounter a dust particle or a solid surface (like a string or a seed crystal), they will tend to adsorb and aggregate on the surface. The solid surface provides the nucleation site for the formation of crystals.
Recrystallization - Recrystallization is a process that has been used to purify solid material by dissolving the solid substance in an appropriate liquid and then having the material come out of solution in crystalline form.
Saturated Solution - Solution where the maximum amount of solutes is dissolved in the solvent.
Seed Crystal - A starting surface for a growing crystal.
Shape of Crystal - The atoms in a crystal occupy positions with definite geometrical relationships to each other. This structural arrangement of its atoms. is uniquely defined by the chemistry of the substance and determines the shape of the crystal. In crystallography, the shapes of crystals can be grouped into seven systems: Cubic Tetragonal Hexagonal Trigonal Orthorhombic Monoclinic Triclinic
Solubility - The maximum amount of solute that can be dissolved in a certain volume of solvent at a given temperature is known as the solubility of the solute. The solubility of the solute usually increases with an increase of temperature. Solute - Dissolved substance in a solution.
Solution - A uniform mixture of two or more substances. For example, sugar dissolved in water is a solution.
Solvent - The liquid into which the solute is dissolved. The solvent of choice in this project is water.