Q&A for How to Grow Alum Crystals

You can definitely use wire. You can also use floss as an alternative to string.

You should use hot water. It should work with cold as well, but it'll take much longer.

It can take more or less time depending on the size of the crystal you want, the environment the crystal is being grown in, climate, weather, and other factors.

Yes, you can grow them on about anything. You just use alum powder and it works the same.

Make a supersaturated solution of alum. Quickly cool it by dipping the beaker in ice water. Afew large crystals will grow. Choose the most perfectly shaped crystal and use it as the seed.

You can cut or grind various shapes, and even make fake diamonds for your collection. You can use dry sandpaper to sand out the basic shape you want, then dip your basic shape in saturated alum solution and start sanding the smaller details. You need to use the saturated alum solution to avoid breaking sharp edges in your crystal. You can dip your finished product in water to clean off the powder and smooth the facets of your crystal.

Any store that sells spices. Alum is a type of salt for pickling. You may even find it in a drugstore in the cosmetic area, as alum is also used to stop cuts from bleeding from shaving.

Yes, but this is not recommended. Increasing the temperature to quickly evaporate the water will also increase the solubility of the solution and maybe even dissolve your crystal. The increase in concentration is also negligible to the total concentration. Lastly, leaving the top open will allow dust to fall into the solution, which may form seed crystals.

The purity may be too low to grow a decent crystal. The alum could also serve another purpose and might require further ingredients.

Yes it typically forms a regular, clear, Octahedral shape but an irregular shape can also be formed.

For the best big crystals, it's all determined by your starting seed crystal. Look for starting crystals that are small, clear, and have a nice shape. The less facets also help grow large crystals. This is because as the Alum falls out of the solution, the crystalline structure is based around the seed structure.

All alum (aluminium potassium sulfate) will work well for crystals. The purity of your alum solution may help reduce the presence of mediums where seed crystals may grow.

Start again with another seed crystal and make sure your solution is saturated enough.

Yes. Putting crystals in the fridge will marginally increase the growth rate of the crystal. This is because lowering the temperature decreases the solubility of the solution.

You can, but the rate of growth of the two will be halved. The best thing to do is use two containers and place your shells in separate containers.

No, you can purchase a pound of alum powder for around $5 USD online and cheaper at most hardware stores.

No, you can use string also. Just be aware that crystals will grow up the whole piece of string. The advantage of nylon is that alum does not adhere to it. You can put Vaseline on the unsubmerged part of the string to prevent this.

Yes, small 1 oz. in the spice section or in the pickling isle. It is expensive though. Runs $2.50 to $3.50 per oz. Crystals are just as good but to experiment, it works fine. If you want larger crystals you should order online for just about $8 to $12 per pound.

Yes. As long as it's pure alum (aluminum potassium sulfate), it will work great.

All forms of alum can cause irritation of the skin and mucous membranes. Breathing alum can cause lung damage. Aluminum also may attack lung tissue. Because it's a salt, eating massive amounts of alum can make you sick.

Approximately 4-5 tablespoons, mass wise 1 tablespoon = 10 grams of alum to 1 cup of water. The ratio seen in science kits is 1 g of alum to 7 mL of water. The trick to make a proper solution is over saturate till it's cloudy and not dissolving anymore. Then let it settle and pour off the clear solution into a new clean jar with no particulate.

It depends on the amount of water you use, say you use 1 cup of water, then you use about two tablespoons (give or take a little).

It usually depends on the concentration of the alum powder, so if you add more alum to less water, you will get a larger crystal.

The crystals are quite brittle, and they will dissolve with water. They might work for something short-termed, like a play item, but nothing serious or lasting.

Once they are clean, fully crystallized and dry, you can put paint on them. However, maybe do a patch test first. Put a tiny dot on your crystal, wait a couple of days to see if anything unwanted happens, and then finish painting it if the crystal is fine.

A seed provides you with a base to grow a large crystal on. If you don't have a seed, crystals will still form, but be less large.

Alum crystals grow best in a warm area. Cold places will still make crystals, but they will take much longer. A heat lamp isn't necessary; just on top of a refrigerator or by a radiator will be fine.

You need to have a saturated solution. You know if they solution is saturated if you keep adding salt and no more will dissolve. It doesn't matter how much water and salt you use, so long as it is saturated.

Yes. Other salt such as Epsom salt make different crystals. It will be interesting to see different results from other salts.

As long as you can dissolve it, it should work. Bits of undissolved alum could nucleate (seed) new crystals.