How to Grow Alum Crystals

Alum crystals are among the easiest and quickest crystals you can grow. Simply mix 1/2 very hot tap water with 2-1/2 tablespoons of alum. You can get alum from the spice section of the grocery store or with canning and pickling supplies. The crystal growth becomes visible after a few minutes. You'll get thumbnail-size crystals in a matter of hours.

If you want to grow a large perfect crystal, choose one of the crystals and remove all of the others. You can add more solution to support the growth of this crystal.

Another interesting way to grow these crystals is to pour the alum solution over a small rock. You'll get a mass of "diamonds" on the stone. This is an easy project that produces a nice display.

Alum crystals are a good project for kids because you don't need boiling water, you're using a safe chemical and you get quick results. Be sure to let me know if you have any questions or need any help.

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[theziggey]

how strong are these crystals?? They don't dissolve in water do they?

[futsang]

@theziggey Yes, they dissolve in water.

[were2cuteforu]

How would i remove the rock from underneath the crystal?? please respond ASAP my project is due before March 7th! :) thanks!

[futsang]

@were2cuteforu These crystals are pretty easy to scrape off of a surface using your fingernail.

[hydrogeddonn]

I've been seeing multiple crystal vids and i was wondering is salt + borax + alum safe?

[futsang]

@hydrogeddonn I would expect the mixture to be safe and to produce non-toxic crystals.

[GaVvAnAtOr]

If i put one of the seeds in the old batch will it grow bigger

[dipolargryphon]

Awsome

[MsCodysimpsonrox]

@futsang i am doign this as a project in chemistry and was wonder how to get a desired shape by using pipe cleaner

[starfaery]

If its aluminium it's not god for your health. Use applecidervinnegar as a deo.

[Khamila1]

@kravmaga99 Use one of the smaller crystals you grew as a "seed" in a second batch and you can get larger crystals.

[kravmaga99]

I've tried this multiple times, and I only get very small crystals along the bottom of the cup/bowl. I've never got the larger crystals described here. Any suggestions?