Hi All and Greetings from New Zealand. I have been baking using my own starter for a few months and have had some success. Recently however I have had the problem of 'too much' oven spring (see photo). I'm using a mix of wholemeal and white flours and after proving the dough goes in the fridge overnight, wrapped in floured cloth. Out after 12 hours and left for two more to warm up. At this stage the dough does seem to have 'crusted' a little and the surface is a bit tough. In the oven at 240C for 10 mins then reduce to 210 for 20 mins. Doesn't seem to matter whether I use a stone or not, always get some split and sometimes the whole loaf nearly splits in two! Tastes good, but would like to hear what I may be doing wrong. Cheers.