You need to get Copper sulfate pentahydrate crystals (Kobbersulfat-pentahydrat), here (US) they are sold as root killer for sewers
Also you will need some Sulfuric acid (svovlsyre), sold here as drain cleaner
In a 4 liter container or larger
Mix 1-3/4 pounds (538 grams) of Copper Sulfate crystals into 1 gallon (3.8 liters) of distilled water
Add 3.5 ounces (103 milliliters) of sulfuric acid to the copper sulfate/water solution
This is the same solution used for copper etching (reverse leads)
http://www.lampworketc.com/forums/sh...hlight=etching