When making sourdough, do I use plain or self-raising flour? We recommend using High Grade Plain Flour, or Strong Bread Flour as the sourdough culture is a mix of culture and yeast.Self-raising flour has baking powder incorporated into it which is not required for sourdough. Related articles How to Guide - Sourdough I’ve left my dough to rise for 48 hours instead of 24 but it isn’t rising as much in the second day as in the first. Have I done something wrong? Can you use this sourdough kit with a bread maker? Is the sourdough yeast gluten free? Does the sourdough culture contain dairy?