UDS Build - got drum but is it lined?

So I am starting to get together supplies to build a uds. I found a drum online (eBay) and was told that although they sell lined drums I could request an unlined drum as they do have some stock.
Drum arrived on Friday but there was no indication on the paperwork or drum itself that its unlined. I have opened the top and inside looks like its painted brown - is this a liner? The drum does say it used to have raspberry juice in it.
How can I tell if its lined?
Drum arrived on Friday but there was no indication on the paperwork or drum itself that its unlined. I have opened the top and inside looks like its painted brown - is this a liner? The drum does say it used to have raspberry juice in it.
How can I tell if its lined?