i mix 40 ml of cider vinegar with 20 grams of copper sulphate into a one liter spray bottle..top with water and it makes the most effective wound spray i have ever used (been using on it on my horses for over 20 years) .. it works equally as well on skin conditions .. copper sulphate prevents proud flesh and kills all skin fungus.
EC: Copper Sulphate is used for its blue coloring in fireworks and paints.
List of sources:
Local plant supply shops
Science Supply Shops