Growing crystals
Crystals have a magical feel although they are the result of a straightforward process by which the atoms or molecules in a solution are highly organized into a structure known as a crystal.
Last updated
Crystals have a magical feel although they are the result of a straightforward process by which the atoms or molecules in a solution are highly organized into a structure known as a crystal.
Last updated
On this page you will find recipes for alum and salt crystals. Sugar or borax crystals can also be made at home safely, and there are many others recipies to be found online. Not all of those are safe to try at home though, so inform yourself well or come to Lab and we will find out for you.
Alum crystals have triangular facets and can be grown on many substrates, such as silk, velvet, felt, cardboard, wood, wool etc.
Alum powder - 125 g (potassium aluminium sulfate dodecahydrate), plus some more just in case
we will try to reorganize these molecules into crystals.
Water - 400 ml/gr
To dissolve the alum powder and reorganize into a crystal
Water - 1000 ml/g
to create a bain marie
Silk - a 10x10cm swatch
Or another substrate for the alum crystals to attach to
Cooker or kettle
A piece of silk
A smooth glass jar or bowl big enough to fit your piece of silk without touching the sides or having to fold or crease it. Make sure this it totally clean.
A wide heat-resistant bowl or oven pan this is the bain marie: the glass jar should fit inside this bowl and have some space for hot water
Spoon
A stick or chopsticks that are long enough to stay put on top of the glass jar.
Clips to fasten the silk to the stick (optional)
Food coloring (optional)
About 80-100% of the alum powder will attach itself the silk in the form of larger crystals.
Preparation
Weigh the alum
Prepare the silk by attaching it to the wooden stick with clips. When you hang it inside the glass jar it should not touch the bottom or the walls of the jar
Boil the water
Put the glass jar inside the wide oven dish/pan. Pour as much boiling water as possible into the bigger pot, without making the glass jar float. This is the bain marie that will keep your crystal solution warm and help it cool down very very slowly (resulting in bigger crystals).
Put this in a (warm) place where you can leave it for 8-16 hours without anyone moving or touching it.
Dissolving the alum
Measure 400 ml and put it in the glass jar (which is already inside the bain marie to keep it warm).
Spoon by spoon, add the alum while stirring. When no more alum dissolves and just sinks to the bottom, your solution is saturated. If there are grains on the bottom, pour off the liquid and clean the jar before continuing. You don't want anything on the bottom of the jar.
Now suspend your silk into the jar, again making sure it doesn't touch any sides or the bottom, and not folded in on itself.
Let the crystals form
Now leave the crystal to grow. The less you touch it, the easier it is for the molecules to find each other on the silk and form big beautiful crystals.
If you have the patience, give it 16 hours. But pretty decent-sized crystals will have formed as soon as 6-8 hours later.
Rinse them under cold tap water and let them dry.
Add a colorant such as black soot ink (other natural dyes are still experimental!)
Turn your crystals opaque white by putting them in the oven for 10 minutes at 100 degrees celcius.
Use different textiles (e.g. velvet attracts many small crystals)
Lay your silk flat in a bowl to cover the entire surface with smaller crystals
Let the crystals grow without the bain marie to see what happens
Glue a piece of silk on an LED with hot glue to grow a crystal that you can use in electronics projecs instead of plastic casings (see video below).
The same technique can be used with epsom salt, sugar and borax.
Adding conductive paint to the solution creates crystals that can be used as capacitive sensors.
Post-processing Store the crystals in a dry place. They will re-dissolve immediately when the are submerged in hot water, starts to dissolve after an hour in water at room temperature, and is completely dissolved after being in water at room temperature for 4 hours.
!! Don't throw away left-over liquid or unused crystals, they can be redissolved a next time.
Salt, or Sodium chloride crystals are cubic in form, they will form on almost any substrate as long as it is not slippery like fishing wire. The size and shape of salt crystals can be modified by temperature.
Table salt - 60-120g , plus some more just in case
we will try to reorganize these molecules into crystals.
Water - 120 ml/gr
To dissolve the alum powder and reorganize into a crystal
A piece of rope, textile
Or another substrate for the salt crystals to attach to
Cooker or kettle
A smooth glass jar or bowl big enough to fit your substrate without touching the sides or having to fold or crease it. Make sure this it totally clean.
A stick or chopsticks that are long enough to stay put on top of the glass jar.
Clips to fasten the substrate to the stick if you can't tie it around (optional)
Food coloring (optional)
About 80-100% of the salt powder will attach itself to the substrate in the form of crystals.
Heat a pan with water. You only need a little bit of water, about 120 ml. Heat the water until it just begins to bubble
Distilled water gives the best results, but tap water should work fine too.
Choose your salt. There are many types of salt. All will form a different shape of crystal. Try these strains and see what happens:
Table salt takes a few days to form.
Epsom salt makes smaller, needle-like crystals, but grows faster than table salt. You can get it at the drugstore or pharmacy.
Stir in as much salt as possible. Remove the pan from the heat. Pour in about 60-120 ml of your salt and stir until the water runs clear. If you don't see a single grain of salt anymore, stir in another spoonful of salt. Keep adding more salt until you see grains of salt that won't dissolve when you stir.
You just made a supersaturated solution. This means that the solution (the moisture) contains more salt than water can usually hold.
Pour the water into a clean jar. Carefully pour the hot water into a pot or other transparent, heat-resistant container. It must be as clean as possible, so that nothing can disturb the growth of crystals.
Pour slowly and stop before the salt grains enter the pot. If there are undissolved salt grains in the jar, the crystals may grow on those grains instead of on your string.
Add food coloring (optional). A few drops of food coloring will change the color of your crystals. It can also make the crystals smaller or more lumpy, but usually not much.
Tie a string around a stick or pencil. The pencil should be long enough to rest over the top of the jar. You can also use a popsicle stick or small stick instead.
The small grooves and rough edges of the rope provide a place for the salt to cling to and grow. A fishing line will not work because it is too slippery.
Cut the rope or textile to the correct length so that it can dangle in the water. Crystals will only form on the part of the rope that hangs under water. Cut it short enough to make sure it doesn't touch the bottom or the crystals may become lumpy and small.
Place the stick or pencil on top of the glass jar. The rope should hang in the pot into the water. If the pencil won't lie still, tape it to the jar.
Try not to let the rope touch the side of the pot. This allows smaller, more lumpy crystals to form against the side.
Put the jar in a safe place. Place the pot where animals and small children cannot reach. Here are some tips for choosing a spot:
To quickly form a clump of crystals, you can put the pot in the sun and/or add a fan to blow it on the lowest setting. These crystals may stop growing if they are relatively small.
If you want a large crystal instead of a clump of crystals, keep the jar in a cool, shaded spot. Place it on a piece of styrofoam or similar material to absorb vibrations. (You still have a good chance of it becoming a clump, but there should be larger, individual crystals in between.)
Epsom salt (and a few lesser-known salts) grows faster in the refrigerator than in the sun.
Wait for crystals to form. Check regularly to see if salt crystals have formed on the string. Epsom salt or alum crystals can start growing within a few hours, but it can also take a few days. Table salt usually takes a day or two to get started, sometimes up to a week. Once you see small crystals on the rope, they will usually grow larger and larger over the course of a few weeks.
Many variations of the recipes above can be found online, such as how to make one very large crystal, or a whole jar full of them.
Alum Crystals on Silk, Loes Bogers Zoutkristallen maken, Wikihow Kristallen kweken, Klokhuis Studio
