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big table salt crystal sugar crystal seed crystals

Growing crystals has been a hobby for some time now. I got the idea from a book, the first book I bought myself as a boy of 10, 11 years old: 'Scheikunde thuis' ('Chemistry at home'). The funny thing is that I didn't try to grow crystals then in 1964. I made my first crystals in 2022.

I started with one of the easiest to grow: copper sulphate (CuSO4.5H2O), bought at Amazon.

My next experiment I did with normal household sugar (C12H22O11), which also worked out really fine.

Next I tried (potassium) alum (KAl(SO4)2.12H2O), which I bought as a deodorant in the supermarket. It didn't work out so good. I also tried kitchen salt (NaCl), without much success. Both I will try to do again soon. I have bought some epsom salt (MgSO4) in a local store and from Amazon I bought iron sulpate (FeSO4). I will try those too soon (probably spring 2024).

Where to get the substances?

As a kid in the sixties I used to buy my chemicals at local pharmacies, but that's not possible anymore. So I use Amazon and eBay to get certain substances I cannot get in supermarkets, plant-growshops or from my own kitchen cupboards. I mailed several chemical companies that manufacture or supply chemicals, but they all seem to sell only in bulk quantities.

How to do it?

It all starts with a (super)saturated solution of a substance in water. This you do by dissolving the substance into hot (not boiling) water untill no substance can be added anymore. Next let the solution cool and then pour a little bit of the solution out in a flat container, like a petri dish. Leave this a few days untill little cristals start forming. Choose the biggest and nicest formed cristal and wrap a piece of cotton thread around it. Not an easy job. Ok, then hang this thread with the seed crystal in a glass container with the saturated solution. The next days and weeks you will see the crystal grow bigger and bigger. It is important to keep the jar in a surrounding with a more or less constant temperature. Sudden changes in temperature affects the growth of the crystals in detrimental ways. This is what probably happened in my experiments with alum and kitchen salt that failed.

Some people use food coloring to give white or transparent crystals some color. I think that's a bit tacky.

I used this precise procedure for the copper sulphate crystal. On the same website are procedures for other substances too.