When we talk about materials such as gold, iron, wood, cotton, etc. in general, we don’t use articles.
The cotton is soft.
Cotton is soft.The silver is shiny.
Silver is shiny.
If we talk about a particular example of a material then we use the.
- The wood I bought is from a pine tree.
(particular example/wood I bought) - The silver used to make this ring is very old.
(particular example/silver in the ring)
