Making terracotta in minecraft - what's the trick?

and if you put a dyed one back in the furnace you get glazed terracotta, the patterned blocks. redstone people like it because sticky pistons can't pull it, which is why it shows up in flying machines.

smelt clay BLOCKS in a furnace, not the clay balls. balls just give you bricks. each block comes out as one terracotta. for coloured ones put 8 terracotta around a dye. or skip all that and go find a badlands biome, the whole place is made of it.