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How to make Copper Hydrate?


Q. Can you explain to me what Cu(OH)2 (Copper Hydrate) is? I want to use it in the process of "granulation", that is, applying tiny balls of silver and/or gold, to another metal surface without using flux or solder. The process involves mixing equal amounts of (finely ground) Copper Hydrate and Seccotine Glue, and mixing it with water to a watery state. The grains of metal are stuck to the base plate with this mixture, and fired in a kiln. I am in Australia, and the pharmacist can get me copper sulfate [linked by editor to product info at Amazon].

wikipedia
Seccotine (adhesive)

Can I turn Copper Sulphate into Copper Hydrate -- and how? Do you know what Seccotine Glue is made from? I can't get it (under that name) in Australia.

Denise D [last name deleted for privacy by Editor]
- Sydney, NSW, Australia

 

A. Yes, you can make copper hydrate from copper sulphate. You will need caustic soda (sodium hydroxide, NaOH), ice and litmus paper.

Dissolve the copper sulphate in water and add ice. Make a dilute solution of the sodium hydroxide. Slowly pour the sodium hydroxide solution into the copper sulphate solution. As the precipitation of Cu(OH)2 takes place, the ice will melt. Keep adding ice to keep the mixture cold. [Note: if you don't add ice, the mixture will turn black, indicating copper oxide, CuO]. Stop adding caustic soda when the litmus paper shows the slurry is basic.
Filter and wash the blue Cu(OH)2 to remove Na2SO4. Air dry only as wet Cu(OH)2 converts to CuO readily with heat.

Dr. Mark E. Keeney
Cincinnati, Ohio


October 22, 2010

A. Seccotine is a fish glue. It is very useful as it is strong and remains flexible after setting. It can be released with water after setting. It is used by model makers (e.g., me), and bookbinders, etc., where waterproof is not required but future release may be. It can be obtained from bookbinder supply houses and some art supply shops in Australia. I saw some recently. When I recall where I will add to this answer.

Geoff MARTIN
- Melbourne, Vic, AUSTRALIA



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