How to use Blood Crucible to corrupt item more than once?

I'm new to POE and still at Act 1. I was able to corrupt several items in the crucible. I heard that you can corrupt an item multiple times, but if I place an already corrupted item (tier 1) in the crucible, it does not seem to acquire any more corruption. There's no corruption bar on that item either. What am I missing here that I don't understand? Or that's for later in the game?

higher item level items can be scourged to tier 2 (level 45) and tier 3 (level 65)


so, for now, youll only be finding low level items that can be scourged once.

most of the best modifiers have ilvl 68 too, so don't worry too much about it till you reach maps and just use it to make rare items (there's a couple exceptions but yeah).

So if i understand correctly, an item with tier 3 scourged cannot be upgraded. Most geardrops at lvl +65 is tier 3, so valueing those items is basically the same as valueing rare drops?