These copper tumbler are enamelled in three layers of a light blue ground glass. The final of the three firings in the kiln is at an extremely high temperature which pulls the copper oxide from the tumbler to create the change in colour and the black markings.
Each tumbler is slightly different due to the enamelling process and these photos are a representaion of the final product.
Usage and care
These tumblers should be washed in warm soapy water before use and thoroughly dried.
Do not use hot in these tumblers as the copper conducts heat.
Do not use acidic liquids as the acid will react with the copper tarnishing it quicker.
If you wish to keep as a decorative item you may polish the inside with a gentle wax to slow down tarnishing and use a copper polish to brighten if it does tarnish.