TasseCeramics

Hi everyone, I've bought numerous clays stating that they fire white and even come with an image to show what colour it will be after fired and glazed, yet my items are a off white/buff colour . Given this has happened with 2 different types of 'white' clay I was wondering if it was me? I don't bisque fire as the kiln I use is an hour away and far too expensive to have everything bisque fired, collect it to paint it and then to take it back to be glazed. Is it because I am not bisque firing first or could it be the glaze? I'm firing it at 1200 using botz 9300 transparent glaze. I've added a picture of the clay I bought and the items I made with it. I'm after more of a bright white like the picture from the website. Also does anyone know of any kilns in the Derby area I can fire my things in?