Tinsel was invented in Germany around 1610. At that time real silver was used, and machines were invented which pulled the silver out into the wafer thin strips for tinsel. Silver was durable, but tarnished quickly, especially with candlelight. Attempts were made to use a mixture of lead and tin, but this was heavy and tended to break under its own weight so was not so practical. So silver was used for tinsel right up to the mid-20th century.