Before the enamel can be applied to the metal (copper, silver or gold), it must be degreased and freed from all oxidation (in the case of copper). Here are three completely harmless and environmentally friendly recipes. However, it goes without saying that even these stains should not get into the eyes and splashes on clothing can cause discoloration.
1. citric acid: dissolve 60 g of citric acid in 300 – 400 ml of water
2. salt and white vinegar: dissolve 1 gr. tablespoon (20 g) of salt in 250 ml of vinegar
3. alum: dissolve 50 g alum in 250 ml water
The mordants work faster if they are heated to about 50°. A teapot warmer on which vessels made of heat-resistant glass or porcelain are placed does a good job.
