In all the guides I have read they say that when producing starter it should be kept at 'room temperature'.
Now 'room temperature' is a very inexact term. In the tropics I guess it's somewhat warmer than in the Nordic countries. Furthermore, my room temperature varies a great deal depending on whether it's day or night, summer or winter. Could this explain why I have tried & failed, numerous times, to produce starter. Should I keep my central heating on throughout the night?
Perhaps, rather than 'room temperature' being the culprit, could there be something in the atmosphere of my kitchen that is killing the starter?
Having failed to produce starter so many times I borrowed some from a friend that had been working for a couple of years. I followed his instructions to the letter & within 2 or 3 days it was dead & smelled horrible.
Now there are many recipes in books & on the Internet that give opposing instructions. Some say you should seal the jar, others not. Some say add either lemon/pineapple juice/raisons/grapes/apple/yeast/sugar/milk/yoghurt or nothing. Some say organic flour or strong white or wholemeal, tap water or bottled,
Seem it doesn't matter what you do or use it should work. For me however, having used many of the above suggestions, it doesn't work - after a day or two it's dead.
So temperature, killer spores or just bad luck.